Billionaire playboy Oliver Queen, missing and presumed dead after a shipwreck that claimed the life of his father, is discovered alive after five years on a remote Pacific island. He is welcomed home to Starling City by his mother Moira, younger sister Thea, and best friend Tommy, but they sense he has changed. Oliver hides the truth about the man he has become, and tries to reconcile with his former girlfriend, Laurel, whom he cheated on with her sister Sara (who died in the shipwreck). While reconnecting with those closest to him, by night Oliver secretly masquerades as a hooded vigilante archer, attempting to fulfil his dying father's entreaty: to right the wrongs of his family, fight the ills of society, and restore Starling City to its former glory. Oliver's first task is to take down corrupt millionaire Adam Hunt, who has scammed millions from various people in Starling City. Laurel's father, police detective Quentin Lance, becomes determined to arrest the vigilante. Meanwhile, it is revealed Oliver's mother has an agenda at odds with her son, having orchestrated a kidnapping to determine what his father told him after the shipwreck.

Laurel brings a civil suit against millionaire Martin Somers, who is also one of Oliver's targets, for taking part in drug trades with the Chinese Triads that ultimately led to the death of a young woman's father. As the hooded vigilante, Oliver threatens Somers to make him confess to the murder as penance for all of the wrongs he has done to the city. Instead, Somers contacts the Triad, who send the assassin China White to kill Laurel. Oliver saves Laurel from China; he later obtains Somers’ confession and gives an audio recording of it to Detective Lance. Meanwhile, Oliver’s mother and Walter push Oliver to take a position at the company. Oliver stymies their efforts by using the opening of the company's new applied sciences division to publicly opt out of the position, knowing that he cannot simultaneously honour his father’s request to fight for the city and be the man his mother wants him to be. A flashback to Oliver's time on the island shows him being attacked by an unknown hooded figure wielding a bow and arrow.

Oliver tracks down another millionaire from his list, but before he can get the answers he wants the man is killed by an assassin known as Deadshot. Initially, the police suspect the vigilante (whom they call The Hood) of the killing, but the evidence goes against that theory. Oliver decides to build a new dance club above his hideout as a cover for his night-time disappearances. While comparing the competition, he finds Thea, who reveals that Laurel and Tommy had been sleeping together during Oliver's absence. Laurel becomes suspicious when Oliver does not react to the news, and concludes he already knew. Meanwhile, Oliver uses the assassin's M.O. to learn his true identity, and, as the vigilante, enlists the help of Detective Lance to prevent Deadshot assassinating more of the wealthy. Oliver stops Deadshot, apparently killing him in the process, but his bodyguard Diggle is shot during the assassination attempt. In order to save Diggle's life, Oliver is forced to reveal his dual identity to him. Flashbacks reveal that the archer who attacked Oliver was actually trying to help him; Oliver misunderstands and escapes, but is pursued by an unknown group of armed professionals.

Diggle awakens in Oliver's hideout, where Oliver offers Diggle a chance to fight at his side and help the city. Diggle turns him down, calling him a murderer. Later, while watching the news, Oliver discovers a connection between Declan, a deathrow inmate, and Jason Brodeur, one of the men on his list. In his vigilante persona, he enlists the help of Laurel to prove the man innocent before he is executed. Working together, the pair uncovers the truth, but Jason Brodeur has his bodyguard stage a prison break so that he can have Laurel and the inmate killed before the truth is revealed. Oliver sneaks into the prison dressed as a guard, with a ski mask to hide his face, and saves Laurel and Declan. The bodyguard ultimately confesses to Declan's innocence. Diggle meets with Oliver and agrees to work with him so that he can both protect the city and protect Oliver from losing his humanity. Detective Lance arrests Oliver on suspicion of being the vigilante after seeing footage of him retrieving his disguise from a bag before confronting Deadshot. Meanwhile, Walter discovers that Moira has been keeping the salvaged and sabotaged family yacht hidden in a warehouse.

When Detective Lance has him charged with murder, Oliver hires Laurel as his attorney. Given Oliver's time on the island, the district attorney offers an insanity plea with open-ended treatment for post-traumatic stress disorder in a psychiatric facility. Oliver declines, instead offering to take a polygraph test to prove his innocence to Detective Lance. The test indicates he is truthful in saying he is not the vigilante. Flashbacks to his time on the island show Oliver caught and tortured by the armed professionals before being saved by the hooded archer. He shows Laurel his scars, saying he is damaged by his experiences. While remanded under house arrest, Oliver throws a prison-themed party, maintaining his bachelor playboy facade. He has Diggle pose as the vigilante and stop a German arms dealer who is in the city to sell automatic weapons to the city's gangs. The plan works and the charges are dropped. Moira meets with a secret associate, who knows of the vigilante's list of targets and sees him as a threat to their organization. Walter leaves the house after confronting Moira on her deception.

Oliver begins preparing to take on another individual from his father's list, but Diggle argues that he should expand his work and help the police take down a group of bank robbers. Oliver initially refuses, believing that it detracts from his mission to right his father's wrongs; Diggle is able to persuade Oliver in the end. Oliver uses police files and IT specialist Felicity Smoak to deduce that the robbers are actually a family unit, and that the leader Derek Reston worked for Queen Industries before Robert Queen outsourced 1500 jobs to China and the Reston family lost their home as a result. Feeling guilty, Oliver tries to persuade Derek to right his own wrongs, but when he learns that the family are going to rob another bank he chooses to stop them. During Oliver's confrontation, Derek is shot and dies. Meanwhile, Tommy throws Laurel a fundraiser to help her pro-bono law firm, CNRI, stay in business; Tommy hopes that this will show Laurel that he is serious about wanting a relationship with her. Flashbacks also reveal how Oliver first discovered the target names in his father's notebook.

While on her way to meet Oliver, Moira is almost gunned down by a mysterious assailant who was attempting to assassinate an associate of mob boss Frank Bertinelli. Oliver attempts to infiltrate Frank's business to discover the identity of the attacker. Frank confronts China White and the Triad gang for the murders of his people. Oliver learns that the attacker is Helena Bertinelli, Frank's daughter, with whom he had just been on a date. Helena reveals that she is looking for revenge against her father, who she blames for the murder of her fiancé. Helena and Oliver are abducted by Frank's right-hand man, Nick Salvati, in connection to the deaths of other mob associates; Helena kills Nick after learning he killed her fiancé. She also deduces Oliver's identity as the vigilante after witnessing him fight her father's henchmen. In the end, Helena confesses to Oliver that she believes that they both share similar stories and that is why they feel connected to each other. Meanwhile, Tommy is cut off financially by his father, who turns out to be the unknown associate that Moira was meeting with regarding the target list. Walter returns home after being away for weeks.

Oliver decides to teach Helena that there is justice outside of revenge after witnessing her try to kill the head of the Triad. Diggle expresses his disapproval, believing that Helena cannot be trusted. Oliver shows Helena that they can bring down her father's business by taking out key players and delivering them to the police. Helena starts to buy into the idea, but after an impromptu dinner with Oliver, Tommy, and Laurel leads to an awkward moment, Helena abandons Oliver's approach, believing he was manipulating her. Helena goes after the Triad, killing their leader. As a result, China White and her men go after Frank Bertinelli, believing him to be responsible, but Oliver gets there in time to stop them. Oliver also stops Helena from killing her father, but she refuses to forgive him for allowing the police to arrest Frank and threatens to reveal his identity if he tries to come after her in the future. Meanwhile, Tommy finally admits to Oliver that his father cut him off financially, and asks for a job working at the club that Oliver is attempting to build. Walter also learns more about the secret organization that Moira is a part of.

Adam Hunt is killed by a mysterious archer; Detective Lance deduces that a copycat is at work, but his superior publicly blames the hooded vigilante. Oliver plans a Christmas party at the mansion to bring back the spirit of the holidays to his family, to which Tommy invites Laurel. A flashback shows Yao Fei's capture of Edward Fyers, who tells Oliver that the island was a prison for dangerous criminals and that his unit was tasked to exterminate the prisoners, including Yao Fei. Yao Fei is captured by Fyers's men while leading Oliver to a possible escape from the island. In the present, Oliver saves some hostages from the mysterious archer, and the two archers are injured after fighting. The mysterious archer gets away but is revealed to be Malcolm Merlyn, Tommy's father. Walter is kidnapped by one of Malcolm's associates to ensure that Moira will not interfere with Malcolm's organization's plans for the city. While recovering in the hospital, Oliver swears to take down the man he believes is behind the archer.

Six weeks after his fight with the mysterious archer, Oliver avoids any activities as his vigilante alter-ego, despite insistence from Diggle that the city needs him. When a firefighter is killed in the line of duty, Laurel suspects that he was murdered and steals the phone the vigilante gave her father in order to contact him for help. Tracking down the suspect, Oliver is bested during the confrontation, but discovers that the murderer is a firefighter. Oliver confesses to Diggle that he has lost his edge, as he now has people he worries about losing should anything happen to him, something he did not have to fear when he first returned from the island. Diggle challenges Oliver that having people to live for is more of an edge than having no one. Oliver learns that the murderer is Garfield Lynns, a firefighter thought to have died in a massive fire several years prior, but who survived with severe burns over his entire body. Garfield shows up at a charity gala for the firefighters intent on getting revenge against the fire chief for not sending backup in the night of his injury. Although Oliver saves the chief, Garfield commits suicide by burning himself. Detective Lance discovers Laurel's deception and plants a listening device on the phone to monitor her communications with the vigilante.

After an armoured truck is robbed, and the drivers killed, Oliver believes that one of the thieves is ex-marine Ted Gaynor, an individual from his target list. Diggle dismisses Oliver's assumption, as Gaynor was Diggle's commanding officer during his first tour of duty in Afghanistan and saved Diggle's life. Oliver goes after Gaynor regardless and steals encrypted data, but Diggle intercedes and prevents Oliver from getting any information directly from Gaynor. The data is revealed to be plans for robbing armoured trucks, which Oliver uses to track and stop the thieves during their next heist. Oliver informs Diggle that Gaynor was not at the heist, but someone from his security firm was. While investigating, Diggle learns that Gaynor was the mastermind behind the robberies, and is forced to join Gaynor's team to recoup the money they lost on the previously failed heist. Diggle backs out of helping Gaynor, who attempts to kill Diggle in retaliation. Oliver arrives in time and kills Gaynor before he can succeed. Afterward, Oliver apologizes for not trusting Diggle more, citing his time of the island when his trust was violated by Yao Fei, who is revealed to have been working with Fyers all along. Meanwhile, believing her mother is cheating on Walter, Thea ingests a new drug, Vertigo, and crashes her car while speeding. She is subsequently arrested by the police for driving while under the influence.

At her arraignment, Thea attempts to enter into a plea bargain with the district attorney, but determined to set an example for the Vertigo drug dealers, the judge dismisses the plea and orders the charges brought to trial. In an attempt to help Thea, Oliver begins working on tracking down the supplier; he eventually discovers that the supplier goes by The Count, and he arranges a meeting through his contacts with the Russian mob. The meeting is broken up by the police, and the Count injects Oliver with a concentrated dose of Vertigo when the latter attempts to follow him. While overdosing, Oliver has flashbacks to the island, and Yao Fei pretending to kill him in front of Fyers so that he can help Oliver to escape captivity. Diggle takes Oliver back to his hideout and uses medicinal herbs Oliver brought back with him from the island to fight the drug overdose. Afterward, Oliver has the drug analysed and uses the ingredients to track the location of the Count. As the vigilante, Oliver is able to confront the Count and inject him with his own drug just as the police arrive as well. Laurel persuades her father to pull some strings and get Thea 2 years of probation and 500 hours of community service, which she begins serving at Laurel's legal office. Additionally, Felicity shows Oliver the list of names that Walter discovered, and informs him that they came from his mother.

Oliver confronts his mother about the list of names, but she denies any knowledge. Diggle does not trust Moira and decides to look into her daily activities. Oliver has flashbacks to his time on the island, where he met Slade Wilson, an Australian Intelligence operative who came to the island to free Yao Fei. Laurel enlists the help of the vigilante when criminal Cyrus Vanch is released from prison on a technicality. Oliver acquires evidence that could put Vanch back behind bars, but Vanch discovers what the vigilante is up to and kidnaps Laurel in an attempt to kill the vigilante and take leadership over the city's gangs. Detective Lance and the vigilante team up to save Laurel, as Lance realizes that Vanch has contacts on the police force and that was how he learned of Laurel working with the vigilante. The pair save Laurel, with Oliver stopping Lance from killing Vanch as revenge for kidnapping Laurel. In order to protect Laurel, Oliver decides that she can no longer have contact with the vigilante. Diggle presents evidence to Oliver that his mother is connected to the group he is hunting, and that she also knew that his father's yacht was sabotaged and kept it to herself. In response, Oliver decides to interrogate his mother again, but this time as the vigilante.

While confronting his mother, Oliver lets his guard down and Moira manages to grab a gun and shoot him. Seeking out Felicity for help, Oliver exposes his secret and asks Felicity to take him to his hideout. With Diggle's help, the bullet is removed and Oliver is stabilized. While unconscious, Oliver has a flashback to his time on the island. Slade Wilson begins training Oliver for an assault on a supply aircraft, which Slade intends to use to escape the island. He also informs Oliver that the man who tortured him was Slade's partner, Billy Wintergreen. He betrayed Slade and joined Fyers. After successfully infiltrating the airstrip, Slade reveals plans to send in an airstrike to wipe out all of Fyers's operation. Oliver heads out to find Yao Fei and save him from the airstrike, but he is recaptured by Fyers. Before he can be executed, Slade arrives, rescuing Oliver and killing his old partner. Although they missed the supply aircraft, Slade and Oliver decide to continue to work together to stop Fyers and get off the island. It is also revealed that Yao Fei changed sides for the safety of his daughter, Shado (Celina Jade), who is held captive by Fyers. Back in the present, Felicity agrees to join Oliver and Diggle, but only until they find Walter. Diggle agrees to back off from pursuing Moira following Oliver's demands, but he is still skeptical of his mother's connection to his father's list of names.

Oliver learns of a jewel thief named Dodger (James Callis), who uses hostages tagged with bomb collars to steal for him, who has come to Starling City. Felicity suggests that Oliver bug the phone of Detective McKenna Hall, an old friend of Oliver's, to gain information on the Dodger. She also convinces Oliver to ask Detective Hall out on a date so that he can have some down time. The date prompts flashbacks to the island, and Oliver recalling a time where he came upon another individual who was beaten and tied up, but refuses to help for fear that it is a trap set by Fyers. Through the wiretap, Oliver is able to determine the Dodger's next location, but is stunned by a bomb thrown by the thief, who subsequently gets away. To draw out the Dodger, Oliver donates antique jewels to a local auction. It works, but Felicity is caught tracking the thief, who places a bomb collar on her as insurance in his getaway. Oliver manages to stop the Dodger and deactivate the collar. Meanwhile, Moira attempts to make a deal with China White to have Malcolm killed, so that she can leave the secret organization and get Walter back.

Oliver stops a hired gunman called Guillermo Barrera who comes to Starling City, but must enlist Felicity to decipher the assassin's phone and determine who the target was. China White hires Deadshot, who is revealed to have survived Oliver's shot with an arrow, to take out Malcolm Merlyn after the previous gunman was stopped by the vigilante. Meanwhile, Malcolm asks Tommy to attend an award ceremony where Malcolm will be receiving a humanitarian award; after much reluctance, Tommy is persuaded to attend by Oliver. At the last moment, Oliver discovers that Malcolm is the target and races to the event to save him. Although he is almost caught by Detective McKenna, Oliver manages to get Malcolm away from China White's men. While in an office, Malcolm is shot with one of Deadshot's poison tipped bullets, and Oliver is forced to reveal his identity to Tommy in order to secure his trust so that he can save Malcolm's life. Afterward, Malcolm informs Moira that he believes someone from the organization attempted to kill him and entrusts her to identify the culprit. Elsewhere, Laurel is confronted by her mother, Dinah, who reveals that her sister might be alive. During a flashback, Oliver is shown repairing a damaged radio from Slade's downed aircraft, which Slade uses to tune into the radio communications of Fyers and his men.

Helena returns to Starling City to kill her father after she learns that he plans to make a deal with the F.B.I. for a pardon on his sentence and witness protection. Helena asks Oliver for help, but when he refuses she attacks Tommy to force his assistance. The pair go after a set of armoured trucks, but Helena is captured by the police when it is revealed to have been a trap. Oliver breaks her out of police custody to protect his secret and demands that she leave Starling City. Instead, Helena forces Felicity to find her father's location. Oliver discovers the truth and manages to stop Helena from killing her father, but when McKenna arrives, Helena shoots her and escapes. In the hospital, McKenna reveals to Oliver that she plans to move to Coast City for her rehab, effectively ending their relationship. Meanwhile, Tommy struggles with his knowledge of Oliver's secret, which in turn affects his relationship with Laurel. Dinah presents her evidence of Sara's existence to her ex-husband and Laurel. In a flashback to the island, Oliver and Slade steal a circuit board to a missile launcher from Fyers and attempt to leverage it as a means to get off the island.

Another vigilante, who goes by The Saviour, appears in Starling City and kidnaps one of Oliver's targets, a slum lord who recently had criminal charges dropped against him because he was able to pay off the District Attorney. The Saviour forces the slum lord to confess his atrocities, only to shoot him dead over a live internet broadcast. When The Saviour kidnaps the District Attorney, and broadcasts his interrogation, Felicity attempts to track his location for Oliver. The signal continues to move and keeps Oliver from being able to save the attorney. The Saviour goes after Roy next, whom he deems as just another gangbanger. Diggle realizes that The Saviour is using an abandoned subway car to travel around the city, and Oliver is able to catch the subway car and stop the Saviour before he can kill Roy. Afterward, Oliver realizes the secret organization's plans involve The Glades, a neighbourhood filled with poverty and crime. Meanwhile, Laurel proves to Dinah and her father, who now believes his daughter survived, that the woman in the picture that Dinah discovered from China was not Sara. Malcolm contacts the Triad to determine who tried to kill him. Moira turns over her co-conspirator Frank Chen to Malcolm, who, dressed in his archer attire, kills Chen and thanks Moira for her loyalty. The flashback to the island shows that Oliver and Slade freed Yao Fei's daughter, but at the cost of Fyers re-acquiring the circuit board.

After a girl dies from using a new form of Vertigo, Oliver sets out to interrogate the Count and determine who is dealing drugs in the Glades. Oliver quickly determines the Count has lost his mind from the Vertigo overdose he received from Oliver months prior. When news reports state that the Count escaped the facility shortly after he left, Oliver suspects that the Count was faking his mental illness. Meanwhile, Detective Lance finds loose connections between Tommy and Vertigo, and attempts to uncover the truth, which almost leads him to discovering Oliver's hideout. Fortunately, Tommy has all of Oliver's gear stored so that Lance does not find anything. Tommy eventually quits the club after realizing that Oliver did not trust that he had nothing to do with any drug dealing; this leads Tommy to ask his father for a job. Felicity isolates an anti-psychotic compound in the drug, and Oliver realizes that the Count's psychiatrist is the one really behind the re-emergence of Vertigo. Oliver stops the doctor, and opts not to kill the Count, who truly lost his mind from the Vertigo overdose and was the unwitting scapegoat of the doctor's actions. Afterward, Oliver decides to help Diggle track down Deadshot, who was responsible for the death of Diggle's brother. In a flashback, Yao Fei's daughter, Shado, begins training Oliver to use a bow.

Laurel represents the Moore family who are suing a corrupt businessman, Edward Rasmus (Al Sapienza), who cheated the family out of their life savings, but a hit is put out on the family, and the couple's young child is the only one to survive. Laurel takes the boy into her custody until his extended family can be reached, but the hitman (J. August Richards) comes after the boy, who can identify him. Laurel is saved by the vigilante, and Tommy suggests that they all go to Oliver's for protection while the police look for the hitman. A sting operation headed up by A.R.G.U.S is set to capture Deadshot, but Oliver chooses to locate the man responsible for hiring the hitman instead of stopping Deadshot. Feeling betrayed by Oliver for choosing Laurel over him, after Oliver agreed to help Diggle kill Deadshot, Diggle decides to leave Oliver. After killing his client, the hitman comes to the Queen residence to kill all remaining witnesses, but Oliver manages to kill him before he can get to Laurel and the boy. Afterward, Tommy decides to leave Laurel, believing that he could never compete with Oliver should she ever discover that he is the vigilante. Elsewhere, Roy continues his search for the vigilante, and Thea agrees to help after seeing how important it is to him. During a flashback to the island, Shado teaches Oliver to shoot a bow but before his skills can be used as their cover, Yao Fei brings Fyers' men to their hideout to capture them all.

Oliver tracks down an accountant, Backman, for the secret organization and steals his laptop in order to redistribute all of his money back to the people he stole from. While decrypting the laptop, Felicity uncovers a link to Walter—a $2 million transfer was made to Dominic Alonzo, an underground casino owner who was hired to kidnap Walter. With Felicity posing as a card sharp, the pair infiltrate the casino; after being beaten and threatened, Alonzo reveals that Walter was killed. Oliver informs his family; Moira immediately confronts Malcolm, who reveals that Walter is alive. Oliver, who was listening in, discovers that Tommy's father is heading the secret organization, and uses Felicity to hack into his phone records to ascertain Walter's location. As the vigilante, Oliver frees Walter and reunites him with the family. Meanwhile, Laurel goes to Tommy to get the truth about why he left, and Tommy reveals that he believes she is meant to be with Oliver, who still loves her. In a flashback, Robert Queen is shown disagreeing with Malcolm's proposed Undertaking, which would involve levelling the Glades and kill thousands of people in an effort to rebuild the area and remove the crime. As a result, Malcolm has a bomb planted on the Queens' yacht just before Robert and Oliver set off. Oliver tracks down an accountant, Backman, for the secret organization and steals his laptop in order to redistribute all of his money back to the people he stole from. While decrypting the laptop, Felicity uncovers a link to Walter—a $2 million transfer was made to Dominic Alonzo, an underground casino owner who was hired to kidnap Walter. With Felicity posing as a card sharp, the pair infiltrate the casino; after being beaten and threatened, Alonzo reveals that Walter was killed. Oliver informs his family; Moira immediately confronts Malcolm, who reveals that Walter is alive. Oliver, who was listening in, discovers that Tommy's father is heading the secret organization, and uses Felicity to hack into his phone records to ascertain Walter's location. As the vigilante, Oliver frees Walter and reunites him with the family. Meanwhile, Laurel goes to Tommy to get the truth about why he left, and Tommy reveals that he believes she is meant to be with Oliver, who still loves her. In a flashback, Robert Queen is shown disagreeing with Malcolm's proposed Undertaking, which would involve levelling the Glades and kill thousands of people in an effort to rebuild the area and remove the crime. As a result, Malcolm has a bomb planted on the Queens' yacht just before Robert and Oliver set off.

Malcolm Merlyn, in his archer costume, goes to Unidac Industries to tie up loose ends by murdering scientists that worked on the seismic device that will be used to level the Glades. Oliver and Diggle devise a plan where Diggle dresses as the vigilante and kidnaps Oliver and Moira in an attempt to uncover the truth about the Undertaking. The plan works and Oliver, Felicity, and Diggle break into Merlyn Global to hack the mainframe and find the device. Oliver convinces Tommy to get back together with Laurel, but when he learns that he could give up being the vigilante if he stops the Undertaking, Oliver decides to reconcile with Laurel himself; later, Tommy witnesses Oliver and Laurel kissing. That night, Diggle goes after the device, but Malcolm learns of the system hack and has the device moved. The vigilante attempts to kill Malcolm, who reveals to the vigilante that he is the other archer; the two fight and Malcolm gets the upper hand, discovering Oliver's secret. Meanwhile, Walter reveals that he knew that Moira was part of his kidnapping and gives her divorce papers as a result. In a flashback, Fyers reveals that he plans to cripple the Chinese economy by blowing up aircraft going into China. Fyers then murders Yao Fei after forcing him to take credit for the attacks via video recording.

Malcolm imprisons Oliver and leaves him to die, hung from chains, but he manages to escape and return home. In a flashback, Fyers fires a missile at an approaching airliner, but Oliver and Shado manage to override the coordinates and destroy the missile. Afterward, Oliver kills Fyers. In the present, Oliver confronts his mother about the Undertaking, which prompts her to hold a press conference and reveal to the city her involvement with Malcolm and the plan to destroy the Glades. Tommy sees the press conference, and Malcolm reveals that he is the other archer to the dismay of his son. Detective Lance, with help from Felicity, is able to dismantle the earthquake device. Diggle and Oliver go after and mortally wound Malcolm, who gloats that there is a second device shortly before he dies. The device activates and begins to level the east side of the Glades. Thea goes into the Glades to save Roy, who heroically works to help others who are trying to escape the earthquake. Laurel is trapped in her office at CNRI, but Tommy arrives to rescue her. Laurel escapes, but Tommy is caught by falling debris. Oliver arrives too late, and Tommy dies from his wounds.

Following the destruction of the Glades and Tommy's death, Oliver goes back to the island alone as penance for failing the city and Tommy. Felicity and Diggle arrive and convince Oliver to return, informing him that Queen Consolidated is in threat of takeover and dissolution by Isabel Rochev. Oliver learns a group of vigilantes, dressed like the Hood, are killing others to take back the Glades. They target Oliver twice before kidnapping Thea. Oliver saves her without killing anyone and leaves the vigilantes for Quentin Lance, who was demoted to patrol officer. Roy is also trying to protect the Glades, and is rescued by an unknown blonde female vigilante. Oliver enlists the help of Walter to save the company. As well, Oliver decides to honour Tommy's memory by becoming a hero of Starling City, and elects to find a new name for his alter-ego. In a flashback, Oliver, Shado, and Slade realize they are not alone on the island following Fyers' demise.

Roy fails to stop a truck robbery committed by China White. When Oliver attempts to convince Roy to stop being a vigilante, he learns that the hospital in the Glades is having its medicine stolen. Oliver sets a trap and finds China White stealing the medicine delivery trucks; the police arrive during the battle and he retreats, allowing China White to get away. Oliver decides to work with Sebastian Blood, an alderman for the Glades, to bring awareness and help for the people in need, but is forced to abandon his appearance at a charity event to instead stop China White. Blood lambasts him in the press. The vigilante convinces Roy to stop fighting in his name, but instead be his eyes and ears in the Glades. Afterward, Laurel sets a trap for the vigilante, who is seemingly surrounded by the police. In a flashback, Oliver, Slade, and Shado discover a cave containing the remains of several cranially disfigured World War II Japanese soldiers.

Oliver is saved from the police by a female vigilante, who quickly vanishes into the night. He sets Roy to track her down, which he manages through the vigilante's connection to a girl named Sin. Officer Lance discovers that the serial killer Barton Mathis, whom he arrested years earlier, escaped from prison during the earthquake and is on the killing spree again. Lance looks to Oliver's alter-ego vigilante for help when he is forced to stay away from the investigation. The pair break into a lab running tests on the evidence found at Mathis's crime scene and are able to discover the link between all of his victims. Oliver learns that Mathis abducted Quentin and Laurel and plans to kill them both. Oliver saves Laurel and Quentin; the female vigilante shows up and kills Mathis after Oliver captures him. During the pre-trial motions for Moira Queen, the district attorney announces his plan to seek the death penalty for Moira's actions in the death of the citizens of the Glades. Later, the female vigilante is tracked down by an agent of Ra's al Ghul; she kills him to avoid having to return to his organization. In flashbacks to the island, Oliver and Slade rush to the aid of Shado who is being attacked. Oliver gets imprisoned by unknown assailants on the boat, Amazo.

Felicity realizes from Oliver's past encounters with the female vigilante that she has been following Laurel. With this information, Oliver manages to ambush her and discovers that she is Sara, Laurel's sister who was believed to have drowned. Meanwhile, weapons shipments are being intercepted by a gang leader calling himself The Mayor, who assaults a gun rally hosted by Oliver and Blood. This allows Felicity to identify the Mayor, and subsequently track him down. Oliver recruits Sara to assist him in capturing the Mayor. Afterward, a corrupt police officer brings The Mayor to an unknown location, where Blood injects him with a green substance that ultimately kills him. Meanwhile, Laurel develops a drinking problem, and refuses help from her father and Oliver. In response, Oliver asks Sara to reveal herself to her family, knowing it will cost him Laurel's friendship. In flashbacks, Oliver is questioned about the bodies of the Japanese soldiers, but when he refuses to answer questions he is taken to an interrogation room where he first learns that Sara is alive.

Sara and Oliver are attacked at Queen Mansion by a man dressed like Malcolm Merlyn. Sara reveals that the man, Al-Owal, is a member of the League of Assassins and is targeting her for leaving the League. Felicity manages to trace Al-Owal to an abandoned manufacturing plant from the dirt he left behind. Oliver and Sara fight with Al-Owal and two other League members to a stalemate. They manage to escape and Al-Owal threatens to kill Sara's family. Oliver manages to protect Laurel, but Quentin refuses to heed Felicity's warning. To protect her father, Sara reveals she is alive to him and brings him to her location in the clock tower. Together with Oliver, they manage to stop the League's second attack, with Sara killing Al-Owal. Afterwards, Sara decides to leave Starling City to keep her family safe, entrusting her secret to Quentin. Elsewhere, Moira, with the encouragement of her children, decides to fight the death penalty charge even after being offered a plea agreement for life in prison. In flashbacks, after being left adrift from the Queen's Gambit wreckage, Sara is rescued and brought aboard the Amazo, where she meets Dr. Anthony Ivo, who asks her to help him with his experiments.

After A.R.G.U.S agent Lyla Michaels goes missing, Oliver charters a trip to Russia to help Diggle find her when they learn that she was following a lead on Deadshot's whereabouts. Isabel Rochev learns that Oliver is going to Russia and tags along, believing that he is trying to meet with the international division of Queen Consolidated behind her back. Once there, Oliver and Diggle learn that Lyla is being held in a gulag. Based on their plan, Diggle is arrested and sent to the gulag to rescue Lyla. Once inside, Diggle finds Deadshot in an isolation freezer. The pair is forced to team up to save Lyla and escape. Afterward, Diggle lets Deadshot go for helping him save Lyla; in return, Deadshot reveals that he was contracted to kill Diggle's brother by H.I.V.E. In flashbacks, Dr. Ivo reveals to Oliver that the Japanese soldiers were transporting a secret serum that would give soldiers superhuman strength and regenerative capabilities. Later, Sara tricks Oliver into revealing that Shado and Slade are still alive. Oliver is nearly executed, but Sara convinces Ivo to spare him.

It is revealed that the Count escaped from prison during the earthquake in the Glades. Afterward, the Count begins poisoning Starling City with the Vertigo drug; Diggle and the assistant district attorney are among the infected. When the assistant district attorney collapses in court, the Count kidnaps him en route to the hospital and reveals to the city that the cure to their sickness is to take Vertigo. In court, Laurel uses an affair between Moira and Malcolm to cast doubts on Moira's defence. Ultimately, Moira is found not guilty by the jury; she later learns that Malcolm Merlyn, alive and well, had rigged the trial. Malcolm also reveals that he now knows Thea is his biological daughter. Felicity is able to locate the Count, and Oliver manages to save the assistant district attorney, but at the expense of allowing the Count to escape. Later, Felicity is captured by the Count when she discovers how he has been infecting the city. In order to protect Felicity from being injected with Vertigo, Oliver is forced to break his promise and kill the Count. Meanwhile, Blood is informed by one of his aids that his test subject - Cyrus - has survived his injection. In a flashback to the island, Shado and Slade rescue Oliver and Sara, after Dr. Ivo and his men travelled to the island to locate the stone arrowhead left by the Japanese soldiers.

When a masked thief with superhuman strength steals a centrifuge from Queen Consolidated, Oliver and his team investigate, with the help of Central City CSI Barry Allen. Oliver suspects that Barry is hiding something and has him investigated. When confronted, Barry reveals that he is searching for super-powered beings in the hope that he will find the one responsible for the murder of his mother. Oliver realizes that the thief was enhanced using the same serum that Dr. Ivo was searching for on the island. Roy and Thea stumbled upon Oliver's case after helping Sin to find her missing friend, but Oliver shoots Roy in the leg to prevent him getting further involved. Oliver tracks the thief, but is injured and injected with an unknown toxin. In order to save Oliver's life, Felicity contacts Barry to help find an antidote. Meanwhile, Malcolm puts pressure on Moira to tell Thea that he is her father. Moira instead contacts Ra's al Ghul, who wants to kill Malcolm for breaking the League of Assassins' code of honour by destroying the Glades. As a result, Malcolm leaves and warns her that the issue regarding Thea is not over. In a flashback to the island, Oliver and Shado find the serum, but when they inject Slade with it his heart stops, just as Dr. Ivo arrives with his men.

Barry manages to save Oliver's life, but Oliver is angry to find out that Felicity has revealed his secret when he regains consciousness. Barry and Felicity are able to identify and locate Oliver's attacker, Cyrus Gold. While continuing to discover the truth behind the death of Sin's friend Max, Roy is captured by Cyrus and brought before Sebastian who injects him with the Mirakuru serum. The serum fails to work and kills Roy. Oliver arrives and stops Cyrus, simultaneously destroying the centrifuge and the remaining serum. Oliver revives Roy, but worries that the serum may affect him negatively. In flashbacks, Ivo kills Shado, but flees when Slade turns up with super-human strength and kills his men. Later, Slade is revealed to be alive in the present and the one orchestrating Blood's work; he orders Blood to leave the vigilante alone, so that he can deal with him personally. While Roy recovers at the Queen mansion, the serum injection heals the arrow wound in his leg. Barry leaves a domino mask for Oliver, to better hide his identity, and returns to Central City. Barry is doused with chemicals and caught in an explosion at his lab after the new particle accelerator explodes during a lightning storm.

Oliver continues his search for the man in the skull mask to no avail. Meanwhile, Felicity has been traveling to Central City to visit Barry who is in a coma due to the explosion. A serial bomber Mark Scheffer, who goes by the name Shrapnel, begins setting off bombs across Starling City as an anti-government movement. Sebastian Blood begins his campaign as mayor, and decides to organize a Unity Rally for the city. Scheffer targets the rally, but Oliver is able to apprehend Scheffer, and the bombs disarmed. During the commotion, Thea witnesses Roy using his new strength and confronts him. Laurel continues to look into Blood, after discovering that he has ties to Cyrus Gold. She visits a mental institution, where she finds Blood's mother, who reveals that Sebastian killed his father and put her in the institution to cover it up. In a flashback, Slade experiences adverse effects to his mind and personality due to the Mirakuru.

Sebastian Blood visits his mother in the sanitarium and learns that she told Laurel that he killed his father. Oliver continues his search for the man in the skull mask, and receives help from Laurel, who suspects that it is Sebastian Blood. Oliver investigates Sebastian, who, fearing that he will be discovered, has Laurel arrested for narcotic possession by his disciple, Officer Daily. Afterward, he has her kidnapped to lure Arrow out. Arrow comes to rescue her, but during a fight Laurel kills the man in the skull mask, who is revealed to be Officer Daily, unknowingly throwing suspicion off Blood. Laurel is cleared of wrongdoing, but is fired when her opiate addiction is brought to light. Meanwhile, Roy and Sin attempt to use his new powers to stop a murderer, but Roy goes overboard and puts the man in the hospital. In order to help, Arrow offers to train Roy to control his new powers as well as his change in mental state. In flashbacks, Sara considers an offer from Ivo to return the Mirakuru for safe passage off the island; after remembering Ivo's torture of the ship prisoners, she declines.

Ben Turner escapes from prison with assistance from Milo Armitage, who also pays him $10 million to steal a prototype of Malcolm Merlyn's earthquake device. Arrow tries to teach Roy self-control, but Roy loses control during a mission and Turner manages to escape with the device. Arrow tracks down the device and is forced to reveal his identity to Roy in order to get his help in destroying the device. Meanwhile, Laurel learns that she may be disbarred because of her addiction, and spirals further out of control. In addition, Moira agrees to run for mayor against Sebastian, and Amanda Waller propositions Turner to commute his sentence in exchange for him joining a squad she is forming. In flashbacks, Oliver struggles with the guilt of letting Shado die and stops Slade from destroying Ivo's freighter with Fyers' missile launcher.

Nyssa Raatko, daughter of Ra's al Ghul and member of the League of Assassins, arrives in Starling City to convince Sara to return to Nanda Parbat with her. Nyssa confronts Sara, and reveals that the two shared a past romantic relationship. Sara refuses to comply, so Nyssa kidnaps Dinah Lance, Sara's mother, and threatens to kill her if Sara does not agree to return with her within 24 hours. Sara agrees, but drinks snake venom in an act of self-sacrifice. Arrow arrives with an antidote, and Nyssa releases Sara from her obligations to the League. Meanwhile, as Moira begins her political campaign, Felicity discovers that Thea's true father was Malcolm Merlyn. Although threatened by Moira, Felicity reveals the truth to Oliver, who supports his mother's campaign publicly while denouncing their familial relationship privately. Although Sara is welcomed back by her parents, Laurel, in a fit of rage, kicks her out of her house after deciding that Sara is responsible for everything bad that has happened to her and their family. In addition, Slade decides to take care of Moira's campaign against Blood.

William Tockman orchestrates a precisely timed heist of Kord Industries and steals an electronic device that will allow him to access any bank vault in the world. His work comes to the attention of Oliver and Sara, who work together to try and stop him, foiling one of his robberies. In response, Tockman uses the device to hack into the computer servers at Oliver's hideout and overload them so they explode. Felicity, feeling left out with Sara now part of the team, attempts to bait Tockman into coming after one last heist. Oliver, Sara, and Diggle arrive in time to protect Felicity, but Felicity takes a bullet while saving Sara before stopping Tockman. Meanwhile, the Lances attempt to have dinner together and it is revealed that Sara and Oliver are in a relationship, much to the anger of Laurel. Later, Laurel reveals the reason for her anger to Sara and they make amends; afterward, Laurel attends an A.A. meeting with Quentin. Slade makes his presence known to Oliver by coming to his home and meeting with Moira. In flashbacks, it is revealed that Sara befriended Sin after promising her dying father, a pilot shot down while flying over the island, that she would make sure Sin was safe.

Discovering that Slade is alive, Oliver is forced by his mother to give Slade a tour of the home. Sara and the rest of the team are notified and arrive at the home to provide backup to Oliver. As Slade leaves, Oliver deduces that he is the one controlling the man in the skull mask, and attempting to create more Mirakuru. Slade informs Oliver that he is there to follow through with a promise he made to Oliver on the island. Later, it is revealed that Slade used the tour to plant cameras throughout the Queen home. In flashbacks, Oliver, Sara, and Slade strategize how to infiltrate Dr. Ivo's freighter. The trio set fire to the Mirakuru, and privately Sara convinces Oliver to kill Ivo in order to keep him from telling Slade how Shado died. Oliver, Slade, and Sara are able to board the ship, with Sara freeing the prisoners, and Oliver and Slade going after Ivo. With Ivo cornered, he reveals to Slade that Oliver chose Sara over Shado. Slade turns on Oliver and imprisons him on the ship as Sara and the other prisoners escape to the island. Slade takes control of the ship and reveals to Oliver that he kept the Mirakuru, having Sara and Oliver destroy an empty box, and tells Oliver that he will not kill him until he has made him suffer the loss of those he loves first, the promise he spoke of.

In a flashback to years prior in Afghanistan, Diggle and Lyla are leading a group of Afghan villagers when one identifies a wanted man, Gholem Qadir, among the group. During an ambush, Diggle saves Qadir's life. In the present, Diggle and Lyla are called upon by Amanda Waller to lead her Task Force X, also known as the Suicide Squad, which consists of Deadshot, Bronze Tiger and Shrapnel being used as expendable assets. The Squad is sent after Qadir, who was released from prison and has developed a deadly nerve agent. Waller wants to use Diggle's past relationship with Qadir to get close to him and steal the weapon. After saving Qadir's life again, through a faked assassination attempt, Diggle is invited to Qadir's home for a party. Once there, Deadshot locates the nerve agent and is expected to be used as a targeting reference for a drone strike on the house. Diggle decides to save Deadshot; as a result, the drone misses the house and a SEAL team is forced to destroy the nerve agent. Meanwhile, Oliver continues to try and deal with the threat of Slade Wilson. Oliver is forced to go to Amanda Waller for help, revealing he has interacted with her before. At first not believing that Slade is alive, Waller tells him that A.R.G.U.S. has been tracking a new mercenary they call Deathstroke, whom the pair realize is actually Slade.

Oliver and Sara assist a police raid, and in the process help capture Frank Bertinelli. Oliver quickly realizes that Frank's daughter, Helena, will return to kill Frank once she learns that her father is in police custody. Laurel is asked to return to the district attorney's office to try Frank's case, but she discovers that it is a ruse to draw out Frank's daughter. Helena shows at the courthouse and takes hostages in exchange for her father. Sara goes to the courthouse, as the Canary, to rescue Laurel, but Helena overpowers Sara and demands that Oliver deliver Frank in exchange for Laurel. Oliver delivers Frank, but he is killed in crossfire with S.W.A.T.; Officer Lance ultimately arrests Helena, after Sara stops her. Despite the ruse, the district attorney rehires Laurel to avoid scandal. Roy breaks up with Thea when he realizes that he is a danger to her as long as he cannot control the side effects of the Mirakuru. In flashbacks, Slade demands Sara return one of the escapees, who can fix the engines of the ship, or else he will kill Oliver. Sara and the other escapees prepare to send the person back against his will.

Initially pretending to comfort Thea after her breakup, Slade uses his opportunity to kidnap her. Distracted by Thea's kidnapping, and having his team work to locate Slade, Oliver gives temporary CEO status to Isabel Rochev so that she can ensure that the company runs smoothly in his absence. Isabel uses her temporary power to convince the board of directors to make her position permanent, thus allowing her company to take full control over Queen Consolidated. When confronted, Isabel reveals that she has been working with Slade the entire time, and tells Oliver where Thea is being held. Oliver arrives, but Thea has already been freed—her kidnapping was a diversion from Slade's real plan to free a group of convicts to be used as test subjects for the next Mirakuru trials. Thea informs Oliver and Moira that Slade told her that her biological father is Malcolm Merlyn. Quentin Lance is arrested for aiding the vigilante, Roy leaves Starling City, and Slade visits Laurel and reveals that Oliver is the Arrow. In flashbacks, Sara attempts to use the trade for Oliver as a moment to kill Slade, but it backfires.

Oliver and his team break into the Applied Sciences division of Queen Consolidated and destroy the lab so that Slade does not have access to it to mass-produce the Mirakuru. In response, Slade attacks the team at their hideout and steals an electronic Skeleton Key, so that he can access any lab to get the equipment he needs. The team is too late and Slade successfully steals a bio-transfuser that will allow him to transfer his Mirakuru-infused blood to the convicts he freed. Oliver tracks Slade and discovers that he has kidnapped Roy and is using him to transfuse the blood. Oliver rescues Roy, and Isabel is mortally wounded in the battle. Later, Oliver reveals there is a cure for the Mirakuru, and Felicity goes to S.T.A.R. Labs to have an antidote created. Meanwhile, Laurel investigates Oliver being the Arrow, which leads her to discover that Sara is the Canary. Laurel stops her investigation when her father tells her that the Arrow's identity is irrelevant to the symbol that he represents. Laurel later blackmails her supervisor into releasing and reinstating her father. Slade's army of Mirakuru warriors gather and Slade uses his blood to heal and empower Isabel as well. In flashbacks, Oliver kills Ivo after he tells him and Sara about the Mirakuru cure.

Roy goes on a rampage, overwhelmed by the Mirakuru and no longer thinking for himself, and attacks civilians. Oliver and Sara track Roy down, but during a fight, Oliver's leg is significantly injured and Roy escapes, killing a police officer in the process. Sara decides that Roy must be killed, but Oliver still wants to save him. Roy comes to Verdant, and Oliver uses the opportunity to inject Roy with pit viper venom to knock him unconscious, and keep him sedated until a cure can be found. Sara decides that she is not good enough for Oliver and leaves the city to find a friend. Thea continues to distance herself from her family, so Moira decides to drop out of the mayoral race at a rally, to focus on rebuilding her relationship with Thea. Oliver convinces her to continue to run, and Moira reveals that she has known Oliver was the Arrow since last year's earthquake, and that she is proud of the man he has become. After the rally, Moira, Thea, and Oliver are attacked by Slade, and Slade murders Moira when she sacrifices herself to save Thea and Oliver. In a flashback to seven years prior, Oliver reveals that he got a young woman pregnant, so Moira pays the woman to tell Oliver she had a miscarriage and never come back to Starling City.

When Oliver goes missing after Moira's death, Diggle and Felicity enlist the help of Amanda Waller to track him down. They find Oliver in a secret hideout, where he reveals his plan to give himself up to Slade in order to save everyone else. Isabel returns and immediately shuts down Verdant, forcing Thea to make a decision to leave Starling City for good. Sebastian is sworn in as Mayor, but Laurel uncovers documentation that he knew Slade was going to kill Moira. Laurel reveals to Oliver that she knows he is the Arrow, and that Sebastian is working with Slade. After confronting Sebastian, Oliver decides that they have no choice but to kill Slade's Mirakuru army. The plan backfires, with Oliver and Laurel cornered by Slade's army, various Mirakuru soldiers wreaking havoc on the city, and Diggle being confronted by Isabel clad in Deathstroke armour. In flashbacks, Anatoli repairs the Japanese submarine that brought the Mirakuru, and he and Oliver prepare to attack the Amazo.

As Slade's men continue to terrorize the city, Felicity joins Diggle and hits Isabel with a van so he can escape, and Malcolm Merlyn returns to the city to save Thea. S.T.A.R. Labs successfully makes a cure for the Mirakuru, but Slade sends men to acquire it before Oliver. Finally trusting Lance, the police force pledges to help the Arrow stop Slade's men, and Quentin is re-promoted to detective to lead the other officers. Slade reveals to Blood that he plans to destroy the entire city, people and all, in his quest for vengeance against Oliver. As a result, Blood steals the cure and gives it to Oliver in return for help saving the city. For his betrayal, Slade has Isabel kill Blood. Oliver tests the cure on Roy after Amanda Waller reveals that she intends to bomb the city at dawn to avoid Slade's men from attacking the rest of the country. In flashbacks, Oliver boards the Amazo to rescue Sara, after she was captured by Slade, with specific orders for Anatoli to destroy the ship if they do not return within an hour. However, they are both captured by Slade.

The cure works, and Oliver and his team must escape their hideout when Slade's men arrive. Back at Verdant, Sara arrives with Nyssa and the League of Assassins to provide backup to take out Slade's men. Equipped with the cure, the team confront Slade and Isabel at Queen Consolidated. Nyssa kills Isabel, but Slade manages to escape. Meanwhile, Diggle and Lyla go to A.R.G.U.S. to force Waller to stop the nuclear strike on the city. Laurel is abducted from police HQ and Quentin is seriously injured. Thea meets up with Roy, but when she finds a bow and quiver she loses trust in him and decides to leave Starling City with Malcolm. Oliver and his team successfully use the cure on all of Slade's men. Oliver tricks Slade into kidnapping Felicity, believing she is one Oliver loves. With Slade distracted, Felicity injects him with the cure. Oliver is able to defeat him, and Waller calls off the bombing. Slade is locked away in an underground A.R.G.U.S. prison on the island, and Sara re-joins the League as payment for helping the city. In flashbacks, Anatoli fires a torpedo into the Amazo, causing it to sink. During the destruction, Oliver presumably kills Slade, and Sara disappears overboard. Later, Oliver awakens in Hong Kong, where he meets Amanda Waller.

Following Slade's defeat, the Arrow is embraced as a hero by the people of Starling City, and newly-promoted Captain Lance calls off the anti-vigilante task-force. Elsewhere, Werner Zytle, who has claimed the mantle of Vertigo, attempts to kill Arrow in a bid to raise his profile. After losing the first battle, Oliver and Roy are able to stop Zytle, along with some help from Sara who is back in town. Meanwhile, businessman Ray Palmer successfully acquires Queen Consolidated under a plan of rebuilding the city and renaming it "Star City".. Laurel helps Lance deal with his health issues, and Diggle and Lyla welcome a baby girl, which convinces Diggle to take Oliver's suggestion and retire from field duty. Oliver and Felicity go on a first date, but Oliver ends it explaining how he can't be the Arrow and Oliver, although he still loves her. After visiting with Laurel, Sara is shot in the chest with arrows by an unseen figure and falls from a rooftop to her death in front of Laurel. In flashbacks, Amanda Waller tries to force Oliver to work for her, and assigns agent Maseo Yamashiro as his handler. After numerous failed attempts to escape, Oliver agrees to proceed with his training to prevent Waller from killing Maseo's family as punishment for his failure in restraining Oliver.

Not knowing what else to do, Laurel takes Sara's body to the team. Laurel demands to help Oliver find Sara's killer, but he forces her to go home. Captain Lance alerts Oliver to another archer in the city killing people, unaware that Sara was killed by an archer. Oliver follows a lead, and with Felicity and Diggle's help, he is able to identify the archer as Simon Lacroix. The team learn who Lacroix's next target is, and are able to stop him before he can succeed. Laurel arrives with a gun, determined to avenge Sara's death by killing Lacroix. As Oliver attempts to talk her out of it, Lacroix reveals that he was not in Starling City the night of Sara's death and leaves Oliver and his team with no more leads as to who killed Sara. The team bury Sara, but Laurel is unable to tell Quentin that Sara is dead. Roy also reveals to Oliver that Thea left town when she learned he was working with the Arrow. In Corto Maltese, Thea is with Malcolm Merlyn and has proven capable of defeating more than one henchman in combat. In flashbacks, Oliver is tasked with killing Tommy Merlyn, after the latter comes to Hong Kong to find Oliver after seeing activity on Oliver's email account. To save Tommy, Oliver pretends to kidnap him and tricks him into thinking that it was a ruse to gain ransom money.

With no more leads in Sara's murder, Oliver focuses his attention on bringing Thea home. Felicity is able to track her to the island of Corto Maltese. Oliver finds Thea working at a restaurant, but she refuses to return to Starling City. While he waits to convince Thea to return, Oliver assists Diggle on a mission for A.R.G.U.S. to ascertain the whereabouts of one of its agents, Mark Shaw. The agent informs Diggle that someone broke into the A.R.G.U.S. database and stole information to sell on the black market. Later, Shaw double crosses Diggle, and reveals that he was the one that is selling A.R.G.U.S. secrets. Felicity helps Oliver and Diggle track down Shaw, and they stop him from selling any secrets. After a last minute plea, and Oliver revealing the truth about how their father died, Thea agrees to return to Starling City. Meanwhile, trying to emulate her sister, Laurel attempts to exact vengeance on an abusive boyfriend of a fellow A.A. member, but she is no match and ends up in the hospital. Later, she seeks out boxer Ted Grant to train her to fight after Oliver's refusal. In flashbacks to six months prior, Merlyn begins training Thea to calm her mind and heal her emotional pain, while also mastering control over physical pain.

Nyssa al Ghul returns to Starling City looking for Sara. Oliver informs her that Sara was killed; Oliver sends Roy to follow Nyssa after it is clear that she knows more about who could have killed Sara. Nyssa is tracked to Sara's old safe house, where Nyssa reveals to Oliver that Malcolm Merlyn is alive and Sara was sent by the League to confirm his existence. After tracking Merlyn, Oliver agrees to meet him in a public location to discuss Sara's death. Merlyn tells Oliver that he did not kill Sara, but only returned to Starling City to take care of Thea. Nyssa kidnaps Thea in an attempt to draw Merlyn out, but Oliver arrives to rescue Thea. Merlyn arrives shortly after to clear his name and insinuates to Nyssa that it was her father, Ra's al Ghul, that had Sara killed. Nyssa does not believe him, but Oliver does and vows to protect Merlyn for as long as he is in Starling. Nyssa warns Oliver that he has made a serious enemy in the League before leaving and reporting back to her father. In flashbacks, Oliver completes his first assassination, and learns that Amanda Waller was behind Edward Fyers' actions on the island.

A cyber terrorist attacks Starling City, threatening to shut down all banks and set everyone on an even socioeconomic status. While Oliver and Roy attempt to keep the peace on the streets, Felicity works to locate the virus that is attacking the city's infrastructure. Felicity quickly realizes that she designed the virus five years earlier, and that it is unstoppable. Felicity's mother Donna shows up unannounced, and the two have a falling out over how different they are from each other. Felicity soon realizes that her mother was unknowingly sent by the cyber terrorist-revealed to be Felicity's ex-boyfriend Cooper-who kidnaps them both. Using Donna as leverage, the terrorist forces Felicity to divert a set of armoured vehicles, carrying newly minted money, to their location. Felicity uses the system to also contact Oliver, who arrives with Roy and Diggle to stop the terrorist and his team. Laurel continues to train with Ted Grant, and reveals to him the real reason that she is learning to fight. Meanwhile, Roy begins having nightmares that he was the one who killed Sara.

A murderer begins taking out gang members in Starling City, and when a body shows up in Ted Grant's gym he becomes a suspect. Oliver follows Ted to another body, where Ted denies killing anyone and reveals to Oliver that he was once a vigilante who retired after a drug dealer was beaten to death by accident. The pair follow the clues to the location where the drug dealer was killed. The murderer shows, which Ted reveals was his former protégé Isaac Stanzler, and who was responsible for the death of the drug dealer, but is bested by Oliver before escaping. Isaac kidnaps Ted and Laurel, but Oliver and his team are able to successfully stop him. Meanwhile, Roy tells Felicity about his dreams and has her run tests on any Mirakuru that may be in his system still. The test reveals no Mirakuru, but Felicity shows Roy other evidence that corroborates his fears. Roy confesses to Oliver and Laurel that he killed Sara. Using a technique learned in Hong Kong, Oliver helps Roy access his memories to realize that he did not kill Sara; however, Roy discovers he did kill a cop while under the effects of Mirakuru.

Oliver begins investigating a new killer in town, who murdered Isaac Stanzler using a bow and arrow, and left his body dressed up as "The Arrow". Following a lead, Oliver learns that the copycat vigilante is a former cop, named Carrie Cutter, who goes by the name "Cupid" and is obsessed with Arrow. Carrie uses a former C.I. to track down Oliver's hideout. Oliver lures Carrie away; when Oliver rejects her romantic advancement Carrie tries to kill the both of them. Oliver stops her, which reinforces Carrie's delusion that he is in love with her. Subsequently, Oliver gives her to A.R.G.U.S. as a new member of their Suicide Squad in the hopes that being on a team will help provide her guidance. Meanwhile, Ray reveals his next plan to help save the city is rebranding Queen Consolidated into Palmer Technologies. Oliver struggles with how much time Felicity is spending with Ray, and the situation is made worse when he walks in on them kissing. Ray is later shown working on a personal exosuit design. In flashbacks to Hong Kong, Oliver and Maseo's wife go off to find her husband when he goes missing.

Oliver and Roy track down the home of Digger Harkness, a boomerang-wielding murderer, but they only find A.R.G.U.S. operatives looking for the same man. S.T.A.R. Labs' Dr. Caitlin Snow and Cisco Ramon arrive in Starling City to help Felicity analyze DNA from the arrow that killed Sara. Digger attempts to kill Lyla; Roy and Oliver arrive to stop him, but need assistance from Barry Allen, who uses his super speed to stop a couple of boomerangs from killing Oliver. Later, Lyla reveals Digger was part of the Suicide Squad, and Oliver agrees to allow Barry to assist in the investigation. Oliver's interrogation tactics lead Barry to question how emotionally stable Oliver is. The team track Digger's location, but it turns out to be a ruse that allows Digger to trace their hideout, where he wounds Lyla before being forced to run away. In order to escape, Digger plants 5 bombs around the city. While Oliver captures Digger, Barry uses both his and Oliver's teams to defuse the bombs at the same time. Flashbacks to Hong Kong show Oliver learning how to torture suspects effectively to get information.

The League of Assassins inform Oliver that he has 48 hours to find and turn over Sara's killer or the league will begin murdering Starling City citizens. Oliver also learns Maseo is now a member of the League. Dr. Snow sends Felicity the DNA profile from the arrow that killed Sara, and the police database identifies Oliver. Believing Malcolm Merlyn set him up, Oliver discovers that Merlyn and Thea arrived in Starling City the night before Sara's murder. Realizing that she has been lying, Arrow confronts Thea, who demonstrates her training with Merlyn, before escaping from the Arrow. Later, Merlyn informs Oliver that he drugged Thea and manipulated her into killing Sara. Merlyn filmed the event to use as leverage to force Oliver into a fight to the death with Ra's al Ghul, with Ra's potential death releasing Merlyn from any blood debt to the League. Oliver and Ra's meet, with Oliver outmatched. Ra's mortally wounds Oliver and kicks him over the side of a cliff. In flashbacks, Oliver and Maseo learn that China White has stolen an engineered super-virus. China breaks into Maseo's house and kidnaps Tatsu.

With no knowledge of what happened to Oliver, Diggle and Roy work to continue protecting the city in his absence. With the Arrow missing, a new crime lord named Danny "Brick" Brickwell plots to take over the Glades. After Thea expresses worry over Oliver's absence, Merlyn investigates the site of the duel and brings a bloodied sword back to Diggle and the others, proclaiming Oliver's death. Diggle discovers Brickwell's plan, to destroy all the evidence against street enforcers so they are released from jail and have to join his crew, and heads to the police warehouse with Roy to stop him. Diggle and Roy are outnumbered, and fearing for their lives, Felicity decides to trap them in the warehouse and let Brickwell escape. Afterward, Felicity proclaims the group non-existent without Oliver and quits. With dozens of men freed because of Brickwell, Laurel goes after them, donning an altered Canary costume. Meanwhile, Maseo finds Oliver's body and takes it to Tatsu so that she can "bring him back to life." In flashbacks to Hong Kong, Oliver and Maseo steal the counterpart to China White's super-virus, thus making her portion inert. Oliver also slips a GPS tracker on one of China's men so that they can locate Tatsu.

Tatsu informs Oliver that his will to live and the cold temperature of the mountain are the only reason he survived. Oliver warns Maseo that Ra's will see his act as a betrayal and kill him for it. While Oliver attempts to rest and heal, members of the League arrive which forces Maseo and Tatsu to kill them to protect Oliver. Maseo cuts himself so Ra's will believe Oliver escaped. Roy and Diggle warn Laurel to stay off the streets, after Roy has to bail her out of a fight. Brick kidnaps the city's aldermen, but when Laurel and Roy track them down, Brick escapes and kills one of the aldermen in retaliation. In exchange for the remaining aldermen, Brick demands that all police presence evacuate the Glades for good. The team is able to locate the aldermen and successfully rescue them, but the Mayor still agrees to remove the police after Brick reveals that he has targeted every legislative body member. Meanwhile, Felicity rejoins the team and provides Ray with the missing piece for his A.T.O.M. exo-suit. Chase, the DJ for Verdant, is revealed to be a spy for the League, who informs Maseo that Merlyn has chosen not to leave Starling. In flashbacks, Maseo makes a deal with China White to give her the counterpart to her virus in exchange for Tatsu.

Worrying about Starling, Oliver decides to leave Tatsu and head home, against her wishes to rest and heal. Tatsu informs him that if he wants to defeat Ra's al Ghul, he will need to seek swordsman training from Maseo. With the police out of the Glades, Roy and Laurel are tasked with fighting Brick's men to keep the peace. Captain Lance gives the team all the information the police have on Brick to help locate him. Merlyn spies on the team as they review the evidence against Brick, and discovers that Brick was responsible for the death of Merlyn's wife. Merlyn propositions the team to join forces to take down Brick, but the team refuses. Instead, they rally the citizens of the Glades to take back their neighborhood by force. Merlyn corners Brick and gets the upper hand. Just as Merlyn is preparing to kill Brick, Oliver arrives and persuades him to spare Brick's life for Thea's sake and let the police arrest him. Oliver, as the Arrow, addresses the citizens of the Glades, commending them for not failing the city and announces that he will not leave them again. In the aftermath, Oliver requests Merlyn train him so that he can take on Ra's al Ghul. Flashbacks chronicle the death of Merlyn's wife and his journey to the League of Assassins to seek training.

While being transported from prison, Werner Zytle orchestrates an escape by poisoning a guard with Vertigo. As Oliver tries to keep Laurel off the streets as a vigilante, Merlyn arrives at the hideout to inform Oliver that to beat Ra's al Ghul he will need to bring Thea into the team. Oliver decides to reveal the truth to Thea who accepts and praises him for the work he has been doing as the Arrow. Laurel tracks down Zytle and takes him on herself, only to be poisoned with Vertigo. Laurel begins to hallucinate images of Sara, who confirms all of Laurel's self doubts. Oliver and Roy arrive in time to save her and get her back to the base for treatment. Later, Oliver brings Laurel along to take down Zytle. Laurel is dosed with Vertigo again, but overcomes her fears to stop Werner. Meanwhile, DJ Chase attempts to kill Thea, but Roy and Merlyn show up; Chase commits suicide when it is clear he has lost. Based on Merlyn's advice, Oliver takes Thea to Lian Yu for training. Laurel meets with her father and finally tells him the truth about Sara. In flashbacks, Oliver attempts to contact his family but is captured by A.R.G.U.S. and interrogated for the location of Maseo and Tatsu. Amanda Waller brings Oliver and Maseo to Starling City to find China White.

While on the island of Lian Yu, Oliver begins Thea's training. After a night dreaming of Sara, Oliver goes to the A.R.G.U.S. prison to visit with Slade Wilson, where he discovers the guard dead and Slade missing. Oliver warns Thea and retrieves a gun from the site of his father's grave, but Slade arrives and captures them. Slade imprisons them in the A.R.G.U.S. cell, leaving them to the same fate Oliver left him. The duo are able to open the doors and escape. Oliver reveals to Thea that she killed Sara, while she grapples with the truth, Slade arrives. The three fight and Thea wounds Slade with his gun, allowing them to imprison him back in the cell. In flashbacks, Oliver and Maseo go to Starling City to track an employee of Queen Consolidated who is working with China White to sell the part of the virus she controls. They track the location of the buy and disrupt the proceedings. Oliver looks in on his family and discovers that Thea is using drugs, and a video message from his father explaining the list of names and encouraging Oliver to save the city.

Oliver and Thea continue their training with Merlyn. Thea struggles with the secret of Sara's death, and confesses the whole truth to Laurel who tells her she isn't responsible; Thea also makes a deal to turn her father over to the League. Laurel confronts Merlyn and is easily outmatched, but they are interrupted by Nyssa and the League, and Merlyn is captured. Oliver decides to go to Nanda Parbat to rescue Merlyn to prevent Thea from losing touch with her humanity when she realizes that she has sentenced her father to death. Oliver and Diggle infiltrate Nanda Parbat, but walk into a trap set by Ra's. Instead of killing Oliver, Ra's expresses his appreciation for Oliver's courage and strength, and asks Oliver to replace him as the head of the League. Meanwhile, Thea confesses the truth to Nyssa and offers her the chance at revenge, and Ray tests the flight capabilities of his completed A.T.O.M. exo-suit. In flashbacks, Oliver is debriefed by General Matthew Shrieve. Afterward, he is promised that he can return home if he pleases. On their way home, Oliver and the Yamashiros are ambushed. Overrun, Oliver flees for safety with the Yamashiros' son.

Ra's al Ghul tries to convince Oliver to take over as the head of the League, and explains that the localized pool of water in Nanda Parbat has healing effects that have allowed him to live far longer than any mortal man. The pool is becoming less effective, so Ra's is looking for a replacement. In a show of good faith to convince Oliver to take the offer, Ra's releases Diggle and Merlyn and forgives all blood debts. Oliver returns to Starling and releases Nyssa, much to the confusion to the rest of the team. Oliver and his team return to stopping crimes, but Captain Lance is done helping the Arrow when he realizes the vigilante lied about Sara's death. Afterward, Oliver realizes that he is not ready to give up being the Arrow; Oliver informs Maseo of his decision, who warns Oliver of the consequences to defying Ra's. Upset with her father for his offer to Oliver, Nyssa returns to Starling City and agrees to help train Laurel. Ra's, dressed as the Arrow, frames the vigilante for murder. In flashbacks to Hong Kong, Oliver and the Yamashiro's son continue to be on the run, during which they seemingly stumble across Shado, who is alive.

Diggle and Lyla officially remarry, but Amanda Waller interrupts their honeymoon to recruit them for a Suicide Squad mission to rescue Senator Cray from a kidnapping. The kidnapping turns out be a ruse by Cray, to help his bid for President. The team rescues the hostages, but Floyd Lawton/Deadshot seemingly sacrifices himself so everyone can get out safely. The police issue a warrant for the Arrow, and Ray publicly announces his own support for the apprehension of the Arrow. Oliver discovers that Ra's has sent multiple assassins to impersonate him until he agrees to take over as the head of the League. In his new A.T.O.M. suit, Ray locates the Arrow and through facial scans learns Oliver is the Arrow. After Laurel refuses to accept Ray's evidence against Oliver he decides to take matters into his own hands. Luring the Arrow to a factory, Ray engages Oliver in a fight, but the latter disables Ray's suit. After, Oliver helps Ray to convince him that he is being framed. Later, Maseo, dressed as the Arrow, murders the mayor in front of multiple witnesses. In flashbacks, Floyd Lawton struggles to transition back into society from the military, including his wife and child leaving him. Floyd is propositioned by an organization known as H.I.V.E. to assassinate Andrew Diggle, John's brother.

After the mayor's murder, Captain Lance issues an arrest warrant for the Arrow and his team, with shoot to kill orders in effect. Ray, having also been shot in the chest and operated on, has a life-threatening blood clot that only his own nanobot invention can dissolve; Felicity administers the cure. Realizing Maseo is the assassin, Oliver uses Nyssa to track his location. Ra's appears and again warns Oliver that not accepting the offer will continue to bring death. The police arrive and Oliver and his team barely escape. To push Oliver to accept the offer, Ra's kidnaps Captain Lance and reveals Oliver's true identity as the Arrow. Captain Lance announces this revelation at a press conference. With his back to a wall, Oliver decides to turn himself in to the police. In order to save Oliver, Roy dresses as the Arrow, stops Oliver's transport van and gives himself up to the police, insisting that he has been the Arrow all along. In flashbacks, Oliver thinks he has found Shado, but it turns out to be her twin sister Mei. A.R.G.U.S. agents come after them, but Maseo and Tatsu arrive to rescue them. Afterward, Oliver tells Mei that her sister and father are dead.

With Roy arrested for being the Arrow, the District Attorney decides not to charge Oliver with any crime. In prison, Roy fends off attacks from the other inmates. While Oliver and his team plot to break Roy out of prison, as well as determine how to stop metahuman Jake Simmons, Captain Lance obtains a search warrant for Verdant and uncovers Oliver's hideout, though he only finds Roy's fingerprints. Oliver enlists Ray's help in stopping the metahuman. After a failed first attempt, Oliver and Ray sync their movements through a neural network, but when the network malfunctions during the battle, Ray defeats Simmons himself, and places him under S.T.A.R. Labs' custody. With the help of a former A.R.G.U.S. agent, Roy fakes his own murder so that the public believes the Arrow is dead and Oliver Queen innocent. As a result, Roy is forced to leave the city. Ra's visits Thea and after a brief fight he mortally wounds her with his sword. In flashbacks, Oliver infiltrates A.R.G.U.S. to stop Waller, only to discover that she did not send the men after him and the Yamashiros: it was actually done by General Shrieve, who plans to release the virus in Hong Kong. Oliver, Maseo, and Tatsu steal the vaccine, as well as the plans for how Shrieve plans to infect the city.

Oliver finds Thea bleeding to death and rushes her to the hospital, where she is stabilized enough for Oliver to make arrangements for her impending death. Maseo contacts Oliver to let him know that if he accepts Ra's offer, he will be able to use the Lazarus Pit to heal Thea. Malcolm warns against this, stating that the pit changes a person in their soul, but Oliver decides to take her to Nanda Parbat regardless. Thea is dipped into the pit and returns healed but in a state of confusion, and her memories jumbled. Knowing Oliver will not leave willingly, Felicity drugs him so they can sneak him out of the fortress. Cornered by Ra's men, Oliver wakes in time to order the League members to stand down. Afterward, Oliver returns to take his place as head of the League, alone. Thea wakes up in her apartment, her mind clear and distraught that Oliver sacrificed himself for her. Oliver renounces his old life, taking on an apprentice role in the League and the name Al Sah-him until he is ready to take over as the new "Ra's al Ghul". In flashbacks, Oliver, Maseo, and Tatsu go after the virus, but during a fight it is released.

Oliver begins his training, which includes breaking down his psyche so that his allegiance is only to the League and his new identity as Al Sah-him. Ra's recounts the moment that he was chosen to become the leader of the League, and a duel with his best friend Damien Darhk who saw himself as the heir. Ra's hesitated and Damien fled, stealing from the Lazarus Pit and starting his own group. Subsequently, Oliver is directed to kill a League member who sees themself as the real heir: Nyssa. Oliver and the League come to Starling City, where Nyssa confronts them. Oliver bests her, but is forced to flee when they are interrupted by Diggle and Laurel. Oliver kidnaps Lyla to force the team to give up Nyssa. At the exchange, a fight breaks out and Nyssa is taken by the League. Oliver almost kills Diggle, but Thea arrives and stops him. In Nanda Parbat, for her betrayal, Ra's orders Nyssa to marry Oliver, and Oliver has to use the Alpha/Omega virus to cleanse Starling City. In flashbacks, Oliver, Maseo, and Tatsu, who were vaccinated, watch as the citizens of Hong Kong, including Maseo and Tatsu's own son Akio, become infected with the virus.

With Oliver gone, Diggle and Laurel patrol Starling City taking on any criminals they find. Oliver learns that Maseo is the one who provided Ra's with the Omega virus when he originally came to Nanda Parbat. Sneaking away from the castle, Oliver reveals that he is in league with Malcolm, and his agreement to become Ra's heir was a charade to get close to Ra's and slowly dismantle the League from within. With Ra's fast tracking his plan to kill everyone in Starling, Oliver is forced to have Malcolm reveal the truth to his friends. The team, including Tatsu, Ray, and Malcolm go to Nanda Parbat where Tatsu kills Maseo before they are overrun by the League and captured. Ra's exposes the team to the virus before sealing them away in a cell. Afterward, Oliver and Nyssa are married. In flashbacks, Akio continues to deteriorate from the virus, his vaccination having not worked. Maseo and Oliver decide to go after General Shreive to see if he has a cure. They only succeed in leading Shrieve to their location, while Akio dies in Tatsu's arms.

While Ra's and Oliver head toward Starling City to release the virus, Felicity and the others wake in the dungeon. Malcolm informs them that he and Oliver created a new vaccine, based on Oliver's blood, which Malcolm used on the team without their awareness. Returning a favor, Barry speeds through the castle disabling the guards and freeing the team. Meanwhile, Oliver reveals his deception and he and Nyssa take out the League's remaining assassins. Ra's escapes with a canister of the virus, vowing to destroy Starling. Oliver learns that Ra's is going to disperse the virus across four points of the city. Felicity locates the four bioweapons, and Oliver organizes the team, along with Captain Lance and the police, to those locations. Oliver is pulled to another location to battle Ra's, as the team successfully stop the virus. Oliver stops and kills Ra's before being shot by a police sniper. Felicity, in Ray's ATOM suit, flies in and rescues Oliver. Afterward, Oliver decides to stop being a hero to the city, instead opting to have a life with Felicity knowing that there are other heroes that can take his place. As payment for his help, Oliver cedes the title of Ra's al Ghul to Malcolm and leaves the league. In flashbacks, Oliver tortures Shrieve for hours in vengeance before Maseo executes him. Maseo leaves Tatsu in grief and Oliver decides to live a life alone to prevent his family from seeing the darkness that has taken over his life.

Diggle, Thea, and Laurel continue fighting crime in Star City, recently renamed in Ray's honor. The city's leadership, which includes Captain Quentin Lance, meet to discuss a group of criminals named the "Ghosts" who are terrorizing the city. Damien Darhk shows up, claiming to control the Ghosts and warning the city leaders to stand aside and let the city die. After they refuse, Darhk systematically begins assassinating each of them but fails to kill Lance. Laurel and Thea contact Oliver, asking him to return to help them stop the Ghosts, much to the disagreement of Diggle. The team tracks the Ghosts, where they witness Darhk using some form of mystical energy manipulation. Working together, the team stop his plot to kill hundreds at a train station. Afterward, Oliver takes the name "Green Arrow" and broadcasts a message to the city vowing to be a beacon of hope, while Lance is revealed to be working with Darhk. In flashbacks: Amanda Waller finds Oliver and forces him back on Lian Yu to assess a new threat.

The team take out another Ghost operation, but Diggle feels like it is not enough and Oliver continues to worry about Thea's excessive aggression when taking out criminals. Meanwhile, Queen family friend Jessica Danforth puts a bid in as the city's new mayor. During her announcement, she is attacked by Lonnie Machin, an anarchist for hire working for Darhk. While trying to locate Machin, Thea's aggressive behavior seriously injures a witness, forcing Oliver to reveal to her the warning Malcolm Merlyn gave him before he put Thea in the Lazarus Pit. The team goes after Machin, successfully stopping him, but Thea again goes too far and sets Machin on fire in the process. Later, Machin escapes police custody en route to the hospital. Laurel decides to take Thea back to Nanda Parbat both to find a way to stop the aggression and to bring Sara's body to the pit. Meanwhile, Oliver decides to run for mayor after Jessica backs out of the race. In flashbacks: Oliver infiltrates a local military operation on Lian Yu run by a man named Reiter. Oliver feigns ignorance of the military operation, but Reiter decides to recruit him for his cause instead of killing Oliver.

Laurel and Thea arrive in Nanda Parbat and request Malcolm, the new Ra's al Ghul, to use the Lazarus Pit to bring Sara back to life. He initially refuses but, in order to appease Thea, he eventually agrees. When Sara returns feral, Nyssa destroys the Lazarus Pit in retaliation. An A.R.G.U.S. operative delivers Diggle information on the woman, Mina Fayad, who hired Floyd Lawton to kill his brother. Fayad also works for H.I.V.E. and meets with Darhk about the growing issue with the vigilantes in Star City. She brings in a metahuman hitman named Jeremy Tell, who can turn his playing card tattoos into physical projectiles. After Tell's initial failure, Darhk kills Fayad for challenging him. Diggle and Oliver team up and take down Tell, but get no new information on H.I.V.E. In flashbacks: Oliver is forced to use torture techniques, after a parcel of drugs goes missing, to interrogate the prisoners who are being used to harvest heroin-cocaine hybrid plants.

Oliver tells the team that he is running for mayor, but is met with apprehension. Lance has Oliver look into the death of two police officers, and the team discovers they were killed by members of the Anti-Vigilante Task Force. Laurel brings her father to see Sara, who is chained up in the basement of Laurel's apartment. The team and Lance set a trap for the corrupt cops, but fail to capture them. Felicity identifies Liza Warner as a suspect, and while searching for her, Oliver discovers Captain Lance meeting with Damien Darhk. Liza and her team use Captain Lance to get into the drug disposal warehouse, but Oliver and his team arrive and take out the officers. Later, Oliver asks Captain Lance to spy on Darhk so they can learn more about his operations, while Laurel discovers that Sara has escaped. In flashbacks: agent Conklin discovers Oliver's communication device with Amanda Waller.

Oliver discovers Sara is alive when he investigates recent murders. With Felicity's help, they determine that Sara, who is still not herself, is looking for Thea and plans to kill her. Sara attacks Thea, who manages to escape. Later, the team captures Sara and Oliver calls an old friend, John Constantine, to help restore Sara's soul. Meanwhile, Darhk gives Captain Lance a new task to install a computer virus in a security company. Diggle goes along and sees his brother's name among the list of individuals being deleted by the virus. Later, Felicity learns that Ray is still alive, and Diggle learns that his brother was killed because he was a drug cartel leader. In flashbacks, Conklin brings Oliver to Reiter, who dismisses Oliver as a spy. Instead, he introduces them to recent captive John Constantine, who escapes and forces Oliver to help him locate a mystical object on the island. After, John warns Oliver after Reiter's real plans, and uses the object to cast a spell on Oliver for his protection.

As Oliver works on his campaign, Felicity continues searching for Ray with the help of Curtis Holt. Ray is able to send a new message, letting Felicity know that he survived the explosion because his suit successfully shrank him down to the size of a pea, that he is being held prisoner, and where to find the schematics to build a device to return him to his right size. In a second message, Felicity discovers that Darhk is the responsible for imprisoning Ray, hoping to get the technology from his suit. As Curtis works on the device, Darhk threatens to hurt Felicity if Ray does not give up his technology willingly. The team tracks Darhk to his hideout and with the device created by Curtis they successfully save and restore Ray. Meanwhile, Sara struggles with the bloodlust and decides to leave Star City to gain control. In flashbacks, Reiter sends Oliver on a search for another ancient ruin that is supposed to yield a "gift" for Reiter.

H.I.V.E. continues to attack parts of the city, most recently destroying money meant for the city bank. Diggle gives Oliver information that H.I.V.E. murdered his brother Andy because he was criminal competition. The team heads to the research lab to locate a chemical they believe is being used by H.I.V.E. The team is attacked by Darhk's group, and Diggle discovers that Andy is still alive and working for H.I.V.E. The team tries to get Diggle to recognize the positive, but he refuses to see Andy as anything more than a traitor and unworthy of saving. The team believes Andy is being mind-controlled and locate him and the rest of H.I.V.E. The team successfully extracts Andy with help from Ray and his ATOM suit. After an encounter with Darhk, Thea learns that his powers may help cure her bloodlust permanently, after Darhk failed to drain the lifeforce from Thea.

Immortal Vandal Savage searches for Kendra Saunders and Carter Hall, two reincarnated beings who have existed for 4000 years, currently being hidden by Oliver, Barry, and their respective teams. Malcolm orchestrates a meeting between Savage, Barry, and Oliver. Savage demands they turn over Kendra and Carter, or he will destroy both Central City and Star City with the Staff of Horus. They devise a plan to deliver the pair as a ruse to get close enough to destroy the staff. The plan fails; Kendra and Carter are killed and Savage uses the staff to destroy everyone else in the city. Barry escapes and runs fast enough to go back in time to the point of the original negotiation with Savage. Barry informs Oliver of his time travel, so they change their approach to their plan. They deliver Kendra and Carter again, but with everyone's help Barry is able to steal the staff. He and Oliver use it on Savage, destroying his body. Afterward, Kendra and Carter decide to use their powers to help others in another city. Meanwhile, Oliver learns he has a son, William, with Samantha Clayton ten years previously after he had Barry run a paternity test, as well as his own mother's deception of this information. He reluctantly agrees to Samantha’s terms to develop a relationship with William without acknowledging their relation, including not telling Felicity. Malcolm collects Savage's ashes.

Oliver's campaign starts an initiative to clean up the Star City bay. Darhk sends a drone to the bay and begins shooting at the citizens helping, injuring several. In response, Oliver and his team decide to call out Darhk as the leader of the Ghosts and H.I.V.E. to the local media. In retaliation, Darhk crashes Oliver's campaign holiday party and kidnaps Diggle, Felicity, and Thea. After failing to get any information from Darhk's soldiers, Oliver makes contact and agrees to exchange himself for them. Darhk tricks Oliver, and attempts to kill them all in front of him. Malcolm, dressed as Green Arrow, and Laurel arrive and rescue everyone. After this Oliver proposes to Felicity, who accepts. As they leave, Darhk sends his men after Oliver again, who shoot up Oliver's limo. Oliver takes control of the limo and manages to narrowly escape Darhk's men. Unfortunately, Felicity is hit by one of the bullets and is mortally wounded. In flashbacks, Oliver returns to the ship the Amazo to acquire more maps of the island, but when he returns he is discovered by Conklin.

With Felicity in and out of surgery for her gunshot wounds, Oliver and the team continue searching for Darhk. Oliver turns to Captain Lance for information on Darhk's location, while Diggle interrogates his brother Andy. They track down Darkh's location, but only find several dead Ghost soldiers and an anarchy symbol painted in blood. The team realize that Lonnie Machin is back and is out for revenge against Darhk. Machin is caught and Oliver interrogates him for information on Darkh. Eventually, Oliver sets Machin free to go after Darhk, tracking him in the process. Machin goes after Darhk's family; the team arrive and save them, but Machin escapes. As repayment for saving his family, Darhk grants Oliver time to spend with his own family before Darhk kills him. Meanwhile, Felicity is left paralyzed from being shot. In flashbacks, Conklin presents Oliver as a traitor and the maps he found as proof to Reiter. While Conklin tortures Oliver, Reiter notices the spell on Oliver's stomach and forces Conklin to stop. In exchange for another prisoner's life, Oliver agrees to help Reiter.

Felicity returns home from the hospital trying to figure out her place on the team now that she is a paraplegic. While Diggle and Lyla are out on a date, an A.R.G.U.S. agent seeks them out for assistance, but he is kidnapped before he can tell the pair what is happening. Diggle and Lyla go to Amanda Waller, who denies any knowledge of what happened, but gives Lyla a portable hard drive that reveals the operative was taken by an organization known as "Shadowspire". Oliver and Diggle recognize the name, with Diggle recalling first meeting the group in Afghanistan when they were war profiteers. With Andy's help, the team tracks Shadowspire. Oliver pressures Felicity for help, who has started having hallucinations of her hacker counterpart. She struggles under the pressure and Diggle is almost killed. Shadowspire infiltrates A.R.G.U.S. looking for a Rubicon access code, killing Amanda Waller when she refuses to help. Oliver and the team, with Felicity, enter A.R.G.U.S. and stop Shadowspire. In flashbacks, Reiter is revealed as the leader of Shadowspire.

The team goes after a burglar, and Oliver and Thea manage to corner him. He escapes when Thea loses consciousness and almost falls off a building. Malcolm reveals to Oliver that this is Thea's bloodlust; since she has not taken a life, the bloodlust is killing her. Felicity tracks the burglar again. Oliver stops him, but when it is revealed to be Roy Harper, Oliver's surprise allows Roy to escape. The track Roy to Palmer Tech, where they discover he is being controlled by a man who goes by the name the Calculator. Felicity tracks the Calculator through the web, who reveals he intends to shut down the entire city killing everyone in the process. The team locates his bomb and destroy it before it can shut down the city infrastructure. Meanwhile, Darhk's wife enters the mayoral race, Thea slips into a coma, the Calculator is revealed to be Felicity's father, and Nyssa escapes her cell in Nanda Parbat to offer Oliver a cure for Thea in exchange for Malcolm's life. In flashbacks, Reiter tortures Oliver for information on the maps he acquired, with Oliver starting to hallucinate seeing Shado.

Oliver refuses Nyssa's offer, instead he attempts to convince Malcolm to relinquish control of the League to Nyssa in exchange for the cure. Malcolm claims Nyssa is lying and refuses to go along, while Nyssa agrees but proclaims that if Malcolm backs out then everyone will be considered an enemy. Oliver convinces Nyssa to provide a sample to prove to Merlyn she is not lying. After witnessing Thea get better, Malcolm agrees to the deal. At the exchange, Malcolm double-crosses Nyssa and she is forced to retreat. Oliver convinces Malcolm to challenge Nyssa to a duel, with the winner remaining the leader of the League. Before they fight, Oliver uses ancient rules to trade places with Nyssa as her husband. Oliver bests Malcolm, but instead of killing him he cuts off the hand wearing the Demon's Head ring and knocks Malcolm unconscious. Oliver exchanges the ring for the cure. Realizing her mistake, Nyssa disbands the League and destroys the ring. Angered by Oliver's betrayal, Malcolm informs Darhk about Oliver's son. In flashbacks, Reiter takes a stone from Oliver that has the symbols he seeks.

Malcolm joins Darhk, his wife Ruve Adams, and the other leaders of H.I.V.E. where it is revealed that they are on "Phase 5" of their plan. In order tie-up loose ends, Darhk sends a group of mercenaries, known as the Demolition Team, to take out Captain Lance. They fail, and Felicity is able to track them to their hideout. Oliver, Thea, Laurel, and Diggle go after them but are almost killed when the Demolition Team destroy their own building to escape. Meanwhile, Thea discovers that Oliver has a son, and supports his decision to keep it a secret. With Curtis' help, Felicity realizes that the Demolition Team are planning to destroy the venue for the mayoral debate between Oliver and Ruve, leaving Ruve alive as a sympathetic survivor. Oliver and his team stop the mercenaries in time for Oliver to win the debate. After, Darhk kidnaps William. In flashbacks, Oliver kills Conklin to win the trust of the other prisoners as Reiter forces them to dig for an "ultimate power" hidden on the island.

Darhk reveals to Oliver that he has William, and he will only return him if Oliver drops out of the mayoral race. Oliver is forced to reveal the truth about his son to the rest of the team, which causes a rift between him and Felicity. Oliver asks a Detroit-based superhero, named Vixen, for help as her powers are derived from magic. Vixen tracks William's location and the team goes in to rescue him. They only find Darhk and his men, as William had already been moved. The attack causes Darhk to demand an immediate resignation from Oliver and support for Ruve Adams. After, the team discovers the root of Darhk's powers and set a plan to destroy his mystical idol. The plan works; Darhk is left powerless and William is saved. They also discover that Malcolm was the one who kidnapped William. Later, Oliver sends William and his mother away for safety. Felicity also decides to break up with Oliver, and with a bio-mechanical implant from Curtis she is able to walk again. In flashbacks, a passage is discovered that leads to Reiter's "ultimate power", and the spell on Oliver's stomach allows him to pass unharmed.

Cupid returns to Star City and begins targeting high profile couples. While the team works to track her whereabouts and prevent any more killings, Laurel works in court fighting Damien Darhk's attempt to have the charges dismissed against him. After several failed attempts find a suitable witness, Captain Lance volunteers to testify to his involvement with Darhk. The team discovers that Cupid is targeting couples that have recently been married. In order to draw her out, Oliver convinces Felicity to stage a "secret" wedding with him to set themselves up as targets, and then leaks the information to the media. The plan works and Cupid attacks Oliver and Felicity at the ceremony. Felicity distracts her long enough for Diggle and Thea to apprehend her. At the trial, Captain Lance's testimony is deemed sufficient to establish probable cause for the charges, and Darhk is remanded into custody without bail. Captain Lance is suspended pending an investigation, while Felicity quits the team for good. In flashbacks, Oliver leads Reiter to a mystical idol, but steals it and runs off into the tunnels.

Brie Larvan orchestrates her release from prison and travels to Star City in search of the bio-mechanical chip that is being used to allow Felicity to walk. Brie attacks Palmer Tech, holding the board hostage until Felicity turns herself over. Curtis tracks down Oliver's hideout, discovering his secret in the process, so that he can offer his help to the team to save Felicity, her mother, and Thea. The team arrives at Palmer Tech, but Oliver is stung by one of Brie's robotic bees. Back at the hideout, Curtis realizes the sting actually implanted a bee within Oliver and it is replicating itself. Laurel uses her Canary Cry to disrupt the frequency controlling the bees to save Oliver. Felicity is able to evacuate the board members, while Brie reveals she is after the chip because she has a tumor that is going to leave her paralyzed. Curtis develops a virus to shut down the bees, which works and uses them to stop Brie. In flashbacks, Oliver goes after Reiter who reveals that the idol has already started to grant him mystical powers. As his powers dwindle, Reiter escapes into the tunnels.

Andy Diggle tells his brother that he was approached by Malcolm about a plan to break Darhk out of prison. Oliver and Diggle foil H.I.V.E.'s plan, but it turns out to be a ruse designed to let Malcolm and League followers invade the bunker and steal Darhk's idol. The team attempts to locate Malcolm, with Andy providing intel. Malcolm delivers the idol to Darhk, but it will not work because it is incomplete. Diggle reveals to Andy that he personally hid the missing piece in another location. Oliver does not trust Andy and confronts him; Diggle interrupts the interrogation and sides with his brother. Darhk orchestrates a prison riot, and the team sets out to stop him, with Andy joining them. However, when the team reaches Darhk, Andy turns on them and gives Darhk the missing piece to his idol. With his powers restored, Darhk stabs Laurel as revenge upon Captain Lance before escaping with Malcolm, Andy, and several inmates. Laurel later dies at the hospital. In flashbacks, Oliver helps the island prisoners escape and sets off a bomb to bury Reiter and keep him from leaving the tunnels.

As the team mourns Laurel's death and tries to determine their next move against Darhk, there is a sighting of the Black Canary stopping an illegal weapons exchange. Oliver discovers that Laurel's sonic device is missing from her belongings from the hospital. The imposter turns out to be a H.I.V.E. prisoner named Evelyn Sharp whom Oliver left behind after he saved his team when they were kidnapped by Darhk, believing that she was with Darhk voluntarily. Captain Lance looks for a way to resurrect Laurel, even soliciting Nyssa al Ghul for help. Diggle, angry at being betrayed by Andy, goes after Darhk's wife, Ruve Adams, but Oliver intervenes to prevent him from doing something he would regret. As a result, Ruve uses her mayoral authority to issue arrest warrants for all vigilantes. Sharp goes after Ruve publicly, but Oliver is able to talk her out of killing the Mayor. At Laurel's funeral, Oliver reveals Laurel as the Black Canary to preserve her image with the city. Afterwards, Oliver vows to kill Darhk. In flashbacks, Oliver and Laurel struggle to come to terms with Tommy Merlyn's death. In the end, Oliver leaves Laurel to cope on her own, and returns to the island of Lian Yu.

Darhk returns to H.I.V.E. and kills the remaining board members before renewing his plans for "Genesis". Oliver and Felicity meet an immortal shaman, Fortuna, who educates Oliver about dark magic. Fortuna explains that Darhk's idol channels darkness and death, feeding him more power, but there is an opposing force that channels light and hope. After a mystical ritual, Fortuna tells Oliver that the darkness inside him is too strong to channel the light. In Star City, Diggle locates Andy, but is captured after a brief shootout. Andy puts a tracking device on him, then allows Diggle to escape so that Darhk and his team can go after Diggle, Lyla, their daughter, and steal a control device to the world's nuclear weapons. Oliver manages to stop Darhk by channeling the power of light, nullifying Darhk's powers and forcing him to retreat. Diggle and Andy battle again, with Diggle ultimately killing his brother. Thea is taken by H.I.V.E. to a secret underground city. The team realizes that Darhk plans to detonate nuclear weapons and build a new world over the ashes.

Darhk begins taking control over the world's nuclear missles. The team seeks out Felicity's father, Noah, to help disable the "Rubicon" program. Darhk sends Danny Brickwell and Michael Amar to find and kill Noah, but Oliver and his team are able to rescue him from Darhk's men. Noah agrees to help, but requires a high-powered processor from Palmer Tech. Felicity learns she has been fired as CEO and is unable to get the processor, forcing the team to break in and steal it. H.I.V.E. locates the team when Noah hacks into "Rubicon". As H.I.V.E. attacks, Felicity and her father shut down "Rubicon" and stop all missiles but one, which launches and heads to Monument Point. Felicity can only redirect it to a less populated town, where it detonates. Oliver and Diggle find Darhk in a nexus chamber, gathering more power from all the deaths caused by the explosion. In flashbacks, Reiter escapes the caves, but Oliver and Taiana steal the idol again. The idol soon begins to affect Taiana.

His power grown exponentially, Darhk attempts to reactivate "Rubicon" with the help of Felicity's former boyfriend, Cooper, and launch the remaining missiles. However, Noah, Felicity, and Curtis successfully shut down "Rubicon" for good. Meanwhile, Oliver and Diggle discover the underground town and track Thea's whereabouts. Malcolm uses a mind-controlling drug on her which makes her turn on Oliver, but Oliver manages to talk her back to reality. Just then, Lonnie Machin takes over H.I.V.E.'s command center and threatens to destroy Darhk's town. Oliver, Diggle and Thea intercede, but the main power source is ruptured and explodes, destroying the city. The town is evacuated and Machin escapes, but not before killing Ruve Adams. In response, Darhk plans to use "Rubicon" to destroy the Earth and shows up at Oliver's home where Felicity, her mother, and Curtis are. In flashbacks, the idol begins to slowly corrupt Taiana, feeding her ever more power from each soldier she and Oliver kill. Oliver takes the idol and tries to talk her down, but Reiter suddenly arrives and confronts them both.

Darhk steals the laptop keeping him locked out of "Rubicon" and launches over 15,000 nuclear missiles, giving the team two hours to prevent worldwide annihilation. With Star City citizens rioting, Oliver addresses everyone directly, inspiring hope in them to stay strong, while Felicity and Curtis divert the missile aimed at Star City. Oliver goes after Darhk, while Felicity, Merlyn, and Thea track down "Rubicon". Felicity is able to convince Cooper to stop helping Darhk, at the cost of his life. Curtis devises a means to stop the missiles. Oliver is able to nullify Darhk's powers with the hope he inspired throughout the city. While the citizens of Star City take on Darhk's remaining men, Oliver and Darhk physically battle, with Oliver killing Darhk. Afterward, Lance, Thea, and Diggle leave the team for new lives, and Oliver is appointed Mayor. In flashbacks, Reiter and Taiana fight; Taiana is able to drain Reiter's life force enough for Oliver to kill him. After, Oliver is forced to kill Taiana, at her request, when she is unable to escape the darkness within. Oliver radios Amanda Waller to rescue the rest of the prisoners and keep the idol safe, intending to go to Russia to honor his promise to Taiana.

Five months after the death of Damien Darhk, Oliver is distracted from his new duties as mayor due to continuing as Green Arrow alone, his old team members having gone their separate ways. He is encouraged by Felicity to build a new team by recruiting the amateur vigilantes now working in Star City, like Rene Ramirez. A new criminal crew appears, headed by Tobias Church, and kidnaps Mayor Queen in a bid to draw out and kill the Green Arrow, thereby taking over the city. He is rescued by Speedy, but she permanently quits the team after seeing that Oliver is again willing to kill. Church escapes from the Green Arrow and a team of several police officers, then later unites all the organized crime cartels and street gangs under his leadership. Oliver finally agrees to form a new team and includes Curtis at the latter's request. Elsewhere, a mysterious hooded figure in black attacks a policeman. In a flashback, Oliver encounters his old friend Anatoli Knyazev in Russia. Anatoli agrees to help him kill Konstantin Kovar, the tyrant running Taiana's village, by initiating him to the Bratva, the only group that can possibly defeat Kovar.

Green Arrow recruits Rene, Evelyn Sharp, and Curtis and begins training them using an extreme exercise from his Bratva initiation, revealed through flashbacks. As mayor, Oliver arranges to have AmerTek provide free medical care for Star City's disenfranchised at a special clinic. A new metahuman, "Ragman", appears and starts attacking AmerTek executives. The recruits leave Green Arrow because they do not trust him. Thea discovers that AmerTek CEO Janet Carroll is working with Church and Felicity learns that it was AmerTek's nuclear missiles that Damien Darhk used to try and destroy the world. Ragman and Green Arrow stop an arms buy between Carroll and Church. Ragman later reveals that he was the only survivor of the Haven Rock bombing. Green Arrow convinces him to put aside vengeance and join his team. Later, Oliver reveals his identity to the other recruits as a sign of trust and they agree to rejoin the team. Thea decides to appoint Quentin as Deputy Mayor. Church is attacked by another archer calling himself "Prometheus", who wants to personally kill Green Arrow. Meanwhile, Diggle, back in the Army and on a covert operation, is ambushed by his superior, who plans to sell a nuclear trigger and frame Diggle.

Green Arrow investigates a new drug, "Stardust", but still believes his team is not ready for the streets. While he is being informed about Prometheus, Rene and Evelyn secretly raid Stardust dealer Derek Sampson's warehouse. The raid goes wrong and Sampson ends up with superhuman strength and an inability to feel pain. Oliver learns what happened from District Attorney Adrian Chase, convincing him that he still cannot trust his recruits. Felicity advises him to accept the recruits as they are, and Green Arrow finally uses his new team to stop Sampson from creating more superhumans. Oliver also publicly endorses Thea's decision to appoint Quentin as Deputy Mayor after negative news stories almost cause her to resign. Felicity admits to Rory, the Ragman, that she was the one responsible for Havenrock. Diggle is incarcerated and hallucinates Floyd Lawton as his cellmate due to guilt over killing his brother. Afterward, he tells Lyla he will not fight the charges against him, so she asks Oliver to help her break Diggle out of prison. Flashbacks focus on Anatoly teaching Oliver the need to trust his brothers in the Bratva.

Oliver's team captures an associate of Church's and delivers him and his loot to the SCPD. Afterward, Rory formally leaves the team saying that he cannot work with Felicity. Oliver leaves Star City to help Lyla break Diggle out of prison, over Felicity and the team's objections. Quentin and Adrian personally deliver the evidence to the SCPD, which turns out to be a disguised bomb. The explosion allows Church's group to break in and steal weapons and equipment. Oliver infiltrates a federal prison and locates Diggle, who agrees to escape to safeguard Oliver. Oliver takes him and Lyla to a H.I.V.E. safe house. Felicity attempts to reconcile matters with Rory. She and the team determine that Church plans an assault on the SCPD's anti-crime unit, where Adrian is interrogating Church's man. Rory rejoins the team, and they help everyone inside escape the attack. However, Curtis is injured and Church captures Rene, intending to torture him to death. Oliver returns and vows to rescue Rene, while Adrian decides to trust the vigilantes' motives. In flashbacks, Anatoli tasks Oliver with gaining information from, and then killing, an associate of Kovar. Oliver completes the assignment, and Anatoli welcomes him into the Bratva.

Oliver rescues Rene, who tells him that he gave up Green Arrow's true identity to Church. Church plans to kill Oliver as the Mayor instead of the vigilante. Diggle rejoins the team and recommends bodyguard Christopher Chance, the "Human Target", to help them. Christopher impersonates Oliver at the City Hall and fakes the Mayor's death when Church's mercenary attacks. The team realizes that Church plans to consolidate the drug traffic of five cities through Star City, needing Green Arrow eliminated for his plan to succeed. Oliver and his team, joined by Diggle and Christopher, raid Church's meeting and capture him and other crime lords. Oliver publicly claims that his faked death was part of a sting operation. Prometheus kills Church during transport, despite Church telling him Green Arrow's identity. Television reporter Susan Williams obtains evidence that Oliver was in Russia during the time he was supposedly stranded on the island. Meanwhile, Oliver finds out that Felicity is dating Billy Malone, a police detective recently assigned to the Anti-Crime Unit. In flashbacks, Oliver is ambushed by other Bratva members. However, the men are killed by Christopher, whom Anatoli had hired to protect Oliver.

Oliver, Diggle and Felicity privately track Prometheus, who starts killing seemingly random civilians with throwing stars. A news report on the killings causes tension in the city and angers the recruits, since they were not informed. Felicity steals one of the stars from Billy to examine. A pattern between the victims relates to Oliver's list from when he started out. This further angers the recruits, Evelyn most of all, as they did not know about Oliver's "kill list" from when he first returned. Felicity uses the pattern to predict future victims, and the team splits up. Evelyn encounters Prometheus and engages him, managing to cut his arm before being overpowered. Oliver then arrives, but Prometheus escapes. Meanwhile, Thea discovers that Quentin never quit drinking. Evelyn reconciles with Oliver, and Felicity tells Billy that she works with the Green Arrow, which intrigues him. She later tells Oliver that evidence she has discovered suggests that Prometheus could be an SCPD officer; Quentin is shown awakening from an alcohol-induced sleep with a slash across his arm and a throwing star in his possession. In flashbacks, during a Bratva operation, Oliver is abducted by Kovar's men and taken to him.

A new vigilante appears in Star City, known as "Vigilante", one who kills criminals in cold blood. Quentin tenders his resignation as Deputy Mayor. He later tells Thea about the throwing star and his drunken blackouts, but believes he is being set up. The team intercepts the Vigilante during a bank robbery, but he gets away, as does Eric Dunn, the head of the robbers. D.A. Chase forces one of the other robbers to reveal Dunn's location, and Green Arrow saves him from the Vigilante. Thea convinces Quentin to go into rehabilitation, while Oliver and Susan start getting closer. The team poses as the bank robbers to lure in the Vigilante, who again escapes even after Oliver defeats and nearly unmasks him. Thea tells Oliver about Quentin and the possibility of his being framed; they deduce that Prometheus must know Green Arrow's identity. Evelyn is revealed to be working for Prometheus. In flashbacks, Kovar introduces Oliver to his servant Galina, Taiana's mother. He also claims that the Bratva has only been using Oliver for their own ends, including making a deal with him. Kovar then releases Oliver back to the Bratva.

Oliver finds himself back at Queen Manor; both his parents are alive, he is about to be married to Laurel Lance, and Diggle is the Hood. However, it is revealed that he, Diggle, Thea, Sara and Ray are all being held unconscious inside pods aboard a Dominator spaceship. Meanwhile, Felicity, Curtis and Cisco Ramon try to hack into the Dominators' mainframe using a piece of their technology. The team recovers a necessary device with the help of the Flash and Supergirl, and they manage to locate the others. Oliver begins seeing flashes of his former life, as do Sara and Ray. All five captives soon realize that they are inside a shared hallucination. Their escape attempt is blocked by manifestations of Malcolm Merlyn, Deathstroke, Damien Darhk and their mercenaries, all of whom are defeated by the captives. The captives then leave the dream and awaken inside the ship. Escaping in a shuttle, they are rescued by the Waverider. Ray deduces that the Dominators were gathering information from their minds, using the hallucination as a distraction, to help them complete a special "weapon". The team learns that the Dominator mothership is headed toward Earth.

This episode continues a crossover that begins on The Flash season 3 episode 8 and concludes on Legends of Tomorrow season 2 episode 7.

Prometheus obtains further intel about the team from Evelyn. He then attacks and hospitalizes Curtis, injecting him with a tuberculosis vaccine developed by Justin Claybourne, a corrupt pharmaceutical manufacturer named on Oliver's former kill list. Flashbacks show that Oliver killed Claybourne after discovering that he financed a TB epidemic, then raised the price on his drug to boost his company's profits. When the team tracks down Prometheus, Evelyn reveals her true allegiance and escapes with Prometheus. Investigating Prometheus on his own, Billy sends information he discovers to Felicity just before the villain captures him. The information turns out to be about Claybourne's illegitimate son, who may now be seeking retribution. Oliver deduces that Prometheus is at Claybourne's former office building and goes there alone. He finds that Prometheus has staged it to resemble Oliver's prior attack. Oliver kills Prometheus, only to discover he has actually killed a gagged Billy, whom the real Prometheus set up as himself to trick Oliver. Curtis's husband Paul leaves him after discovering Curtis is a vigilante; Felicity mourns Billy's death; Diggle is recaptured; and Oliver finds what seems to be Laurel Lance alive and well inside the lair.

Laurel states that Sara revived her after her murder. Oliver welcomes her into the team; but Felicity soon realizes that she is Laurel's doppelganger from Earth-2, having been broken out of S.T.A.R. Labs by Prometheus. Laurel escapes and calls Oliver for an arrangement near the Black Canary statue. Though he remains optimistic towards Laurel, Felicity orders the others to attack Laurel, leading to the destruction of the statue, though she is captured. Learning about Paul, Rene convinces Curtis to move on and focus on his capabilities, not his flaws. At a second meeting, Curtis is able to disable Laurel's scream, allowing Felicity to knock her out. Though Prometheus escapes, Laurel is captured, and Oliver places her in an A.R.G.U.S. facility, hoping to change her one day. While Felicity admires his optimism, Oliver tells her of his plans to follow (Earth-1) Laurel's dying wish, to find and recruit another Black Canary. In a bar in Hub City, a woman with a sonic scream stops an attempted assault in a bar. Meanwhile, Oliver convinces Adrian to represent John. The latter's corrupt superior, General Walker, arrives to assume his custody; but Adrian manages to bring John to his own jurisdiction. In flashbacks, Gregor, the Bratva traitor, attempts to force Oliver's obedience; but the latter is rescued by a female archer named Talia.

During the S.T.A.R. Labs incident, CCPD undercover officer Tina Boland develops a sonic scream after watching her partner die at the hands of drug dealer Sean Sonus. In the present day, Adrian tells Oliver that the NSA has been investigating Walker, but the files are not accessible. Tasking Felicity and Rory to get the files, Oliver takes the others to recruit Tina, who has tracked Sonus to Hub City. She initially refuses to join, but Oliver's team intercepts her attacking Sonus, who is revealed to be a metahuman capable of using her powers against her. Sonus escapes, and Oliver reveals his identity in an attempt to convince Tina, who later attacks Sonus during a transaction. Oliver's team intervenes and helps her defeat the dealers, but Oliver fails to dissuade her from killing Sonus. Meanwhile, Felicity meets a hacktivist, whom she inspired during her college days, who gives her the files against Walker. With them, Adrian is able to get John released on bail. Tina meets Oliver and announces her decision to join the team after revealing that her real name is Dinah Drake. In flashbacks, Talia helps Oliver kill an important associate of Kovar's. She reveals that she trained Yao, and gives him the suit he will use when he first returns to Starling City.

In flashbacks, Oliver and Talia kill an illegal drug merchant from Robert Queen's list. Talia again presses Oliver to return home, but he chooses instead to help Anatoli kill Gregor. In the present, the team learns that Walker is in Russia for a deal with Markovian terrorists. Oliver takes everyone except Rene, who is tasked to help Quentin with his interview with Susan. Anatoli refuses to help Oliver unless he does something criminal in return, which Oliver initially refuses. After Felicity blackmails a Russian analyst, the team manages to capture Walker's henchman, whom John tortures, but to no avail. In order to prevent John and Felicity from acting against their own morals, Oliver accepts Anatoli's terms and attacks a rival with Dinah's assistance. Team Arrow and the Bratva intercept Walker's deal; and John decides to spare Walker, who is arrested by the Military Police, while Rory uses his rags to contain the nuclear blast. Upon returning, Oliver sleeps with Susan, who later stealthily deduces his alter-ego after learning about a similar hooded vigilante in Russia five years prior through her source. Rory tells Felicity that his rags do not function anymore, and he needs to leave temporarily. Meanwhile, with Rene's help, Quentin's interview is successful, and they become friends.

16 months ago, Rene watched his wife, an addict, being killed by a dealer in front of the former's daughter, Zoe, who was transferred to foster care, and Rene was prohibited from seeing her. He was inspired by the Green Arrow killing Darhk and saving Star City, deciding to start his vigilantism. In the present, Rene now works for Quentin as his assistant. An armed man attacks the city hall and kills and wounds several staff members. Felicity identifies the shooter as James Edlund, a former clerk and a gun control proponent who lost his family in a shootout months ago. Thea and Quentin encourage Oliver to deal with the situation as the mayor, not the vigilante. The latter decides to work with the city council for a gun control act. Rene and Curtis locate Edlund's hideout and find his next target, where Oliver confronts Edlund as the mayor and dissuades him from killing anyone, convincing him to surrender. Oliver reaches to an agreement with the council over the act. Curtis promises Rene to help him get to Zoe legally. Meanwhile, John convinces Dinah to return to normal life. She enlists in the SCPD.

Oliver meets Prometheus's alleged mother, who refuses to help him. During a prison transfer, Chien, Carrie, and Warner kill the guards and escape. Oliver appoints Dinah as an SCPD officer. Pike receives evidence that the Green Arrow killed Malone, and he orders a manhunt. Oliver and Quentin track down the trio, who escape due to the intervention of the ACU. Oliver surmises that Prometheus is responsible for sending the evidence. Susan confronts Oliver for being the vigilante, which he denies. Thea discredits her by having Felicity hack Susan's files and insert proof that she committed plagiarism. Susan gets angry with Oliver, who confronts Thea. He reveals the cover-up of Malone's death to Pike. The team intercepts the trio stealing money from a stash left by Church, and are ambushed by their mercenaries. The ACU arrives and arrests the trio, allowing Team Arrow to leave. Quentin gives Dinah his blessing to assume the Black Canary identity. Word of the cover-up is later leaked to the media, which could lead to Oliver's impeachment. In flashbacks, Oliver and Anatoli engage Gregor's men. Gregor prepares to kill Anatoli.

Oliver's impeachment process begins, with Adrian serving as his attorney. The Vigilante starts targeting the former, but is opposed by Prometheus, who is revealed to be Adrian. Using Pandora, Felicity and Thea learn about a secret that can be used to blackmail an alderman. Oliver and John dissuade them from using the method. Using a piece of the Vigilante's suit, Curtis manages to track his location, where he plans to kill Oliver, who publicly disavows the Green Arrow as a "cop killer", stating his motive for the cover-up as to protect the people from losing hope. The Vigilante escapes. The council votes against impeachment. However, Thea resigns from Oliver's administration in order to work on her morality. Paul decides to divorce Curtis. Susan gets her job back by Felicity's anonymous testimony, then latter secretly joins the Helix. Adrian aggressively demands Susan to listen to his story. In flashbacks, Anatoli demands a "spross dopross", a process to depose the Pakhan. Oliver infiltrates Kovar's mansion and acquires evidence that Gregor has been embezzling the Bratva's money. The majority of the captains vote for Anatoli; but Gregor starts a mutiny.

Oliver meets Talia, who reveals herself as Ra's' daughter and that she hates the former for killing him, before revealing that she helped Adrian become Prometheus. Oliver confronts Adrian, who reveals that he has kidnapped Williams, who will starve if the former kills Adrian. The Green Arrow breaks in Adrian's house and tries to reason with Doris before the ACU storms in, forcing him to escape. Felicity agrees to hack DHS drones for HELIX, which finds Williams' location in exchange. Oliver's team enters the building and the former manages to find and rescue Williams before he confronts Adrian. Diggle brings Doris, who attempts to convince Adrian to surrender, only for him to stab her. Oliver engages Adrian while the others take Williams and Doris away. Talia arrives and helps Adrian overpower Oliver and abduct him, while Doris succumbs to her wound. Adrian tells Oliver that he plans to help the latter learn who he is really. Meanwhile, Adrian continues acting normally in the City Hall, angering the team. In flashbacks, most of the captains are killed in the shootout before Gregor escapes. Oliver and Knyazev attack Gregor during his meeting with his loyal Bratva members and kill him.

In flashbacks, Anatoli becomes the new Pakhan. Kovar buys Sarin gas from Malcolm. Anatoli learns that Kovar is planning a coup against the Russian government. By torturing an operative of Kovar's, Oliver learns that Kovar has invited key government officials to his casino, where he plans to assassinate all of them by the gas. Oliver convinces Galina, Taiana's mother to give him her key card to the casino. Oliver and the Bratva infiltrate the casino, where Kovar learns about Galina's betrayal and kills her, angering Oliver, who fails to stop the spread of the gas in time, leading to Viktor's death. Anatoli fails to persuade Oliver from killing Kovar. The former appoints him as a Bratva captain. Malcolm helps Kovar's operatives revive him. In the present, Adrian continues torturing Oliver to make him confess a "secret". The former brings a seemingly reluctant Evelyn, apparently killing her after Oliver refuses to do it. Oliver reveals that he killed people because he liked it, which Adrian wanted to hear. Evelyn is revealed to be alive and still assisting Adrian. Adrian lets Oliver go, and he returns to the hideout and tells the team about his decision to end his vigilantism.

With Chase having broken him, Oliver disbands Team Arrow and calls in the Bratva to take out Chase. Diggle tries to talk Oliver out of it, reminding him that there are better ways of doing things. Felicity goes to Helix and manages to find pixelated footage of Chase taking off his Prometheus mask. Oliver allows the Bratva to steal diabetes medicine, before they are stopped by Team Arrow. Diggle eventually tells Oliver they can fix him, if he asks for help. Oliver rejoins Team Arrow, taking out the Bratva and saving hostages that Anatoli had taken as leverage. Felicity and Curtis manage to decode Chase's device, revealing Chase as Prometheus to the police. Oliver claims he's not ready to put the hood back on yet, but with his team, it will be sooner rather than later. When his guards try to arrest Chase, Chase kills them and leaves his safe house. In flashbacks, Oliver plans to return to Lian Yu, so Anatoli plans one last heist to help sick children, hoping to convince Oliver to stay, but Oliver decides to still return to Lian Yu, so he can stage his dramatic return to Starling City.

With law enforcement agencies unable to locate Chase, Felicity agrees to Alena's plan to free former Helix leader Cayden James, who has created a biometric tracker that can find anyone, but who is currently in Argus custody without due process. Lyla plans to use James as bait to destroy Helix but Alena, having already anticipated it, finds James' true location and leads her team, including Felicity, to the rescue. They are interrupted by Team Arrow; but Felicity forces them to allow Helix to escape with James. Helix end their connection to Felicity, but provide her with James' scanner, which she uses to learn that Chase is already in the team hideout, starting an assault. Meanwhile, Quentin confronts Rene for not visiting Zoe, though legally possible. Rene believes himself to be an unsuitable father. However, Quentin organizes a visit, making Rene decide to fight for reclaiming Zoe. John confronts Lyla for her moral ambiguity, which led to their divorce previously.

Chase triggers an EMP within the team hideout, deactivating all the equipment, stranding Oliver and Felicity and rendering her paralysed. Curtis learns about the attack, informing Rene and Dinah. Diggle and Lyla agree to put their problems aside when they hear about Oliver and Felicity. The team soon realizes that after a period of time, a backup generator will activate, igniting the methane gas leaking into the base. Oliver is injured trying to find a way out. Eventually, Diggle is lowered down an access shaft by the others' help and manages to pull up Oliver and Felicity. Team Arrow takes refuge at Argus, where Diggle and Lyla reconcile. Later, Chase is revealed to have tracked down Oliver's son, William. In flashbacks to the period after Darhk's death, Oliver, Felicity, and Curtis continue working together. Curtis arranges to have Oliver and Felicity spend time together, leading to having sex in the lair, but she decides that she is not ready to get back together with Oliver, who accepts it.

Chase's prosecutions are discredited and most of the convicts, including Sampson, are released on bail. Oliver is sent a body, identified as Henry Goodwin. While Curtis and Dinah track Sampson, the others investigate Goodwin, who is revealed to have been killed by Robert Queen, shocking Thea and Oliver. The team deduces that Chase and Sampson are working together to release Claybourne's weaponized tuberculosis in Star City. With Oliver wearing the Green Arrow costume again, they track the bomb and engage Sampson's party while Oliver duels Chase. Sampson is captured as Curtis defuses the bomb. Oliver reveals that Claybourne planned to disown Chase due to Chase's mental condition. Disillusioned, Chase asks Oliver to kill him, but Oliver arrests him instead. Oliver gives Thea a video of Robert asking her to look after Oliver. Meanwhile, Rene refuses to testify in court so as not to upset Zoe, leading to the judge dismissing his claim. In flashbacks, Oliver and Anatoli return to Lian Yu, where they arrange for Oliver's return to Starling City. Anatoli leaves to bribe the boatmen to sail towards the island, but Oliver gets captured by Kovar, who knows about Oliver's plan.

The team holds a birthday party for Oliver, but Rene, Dinah, and Curtis are later kidnapped by Chase's outside team. Realizing that Chase is picking them off after Thea and Quentin are kidnapped by Black Siren and Evelyn, Oliver accepts Malcolm's aid to help him lean on Chase. However, Chase reveals he has kidnapped William and Oliver is forced to free him. Felicity and Diggle are kidnapped by Talia and the League of Assassins, Oliver recruits Nyssa to help him fight Chase's army. Tracking a plane carrying Chase, they realize they are going to Lian Yu. Arriving on the island, Oliver visits Slade and asks for his help. In flashbacks, Kovar injects a drug into Oliver that forces him to suffer visceral hallucinations of painful moments from the last five years. After enduring visions of Yao Fei and Laurel, Oliver eventually finds the strength to escape.

Oliver recruits a Mirakuru-less and hate-free Slade Wilson. Harkness reveals his allegiance to Chase. Oliver's party frees Felicity, Thea, Curtis, and Samantha, trapping Evelyn. Oliver asks Malcolm to take Felicity's party to Chase's plane in order to escape and manages to free John, Rene, Dinah, and Quentin, who knocks Black Siren unconscious while Nyssa defeats Talia. Malcolm kills Harkness, but sacrifices himself by taking Thea's place on a tripped landmine, allowing Felicity's party to escape. They reach the plane, but learn that the whole island is rigged with C4, which will detonate if Chase dies. Oliver asks John to lead the others to Felicity's party and escape while Oliver captures Chase on a boat and frees William, who learns that his father is the Green Arrow. The plane is sabotaged, so Oliver tells the others to run to a ship on the eastern shore. Unsure of the others' fates, Chase kills himself in front of Oliver and William, causing the bombs to demolish Lian Yu. In flashbacks, Oliver kills Kovar and his men, reaching the boat in time and calling Moira.

In flashbacks, Slade heads to the A.R.G.U.S. ship alone while the others take refuge in the plane. Samantha runs off to find William, with Thea following her. John's right pectoral muscles are injured while rescuing Felicity. Oliver finds Thea in critical condition, and a dying Samantha asks him to look after William. Dinah and Quentin are attacked by Black Siren, whom he shoots. She is later saved by an unknown man. In the present, Thea is still comatose and William blames Oliver for Samantha's death. Black Siren and her mercenary team attack the SCPD station. During another confrontation, John accidentally wounds Rene due to his injury. Determining Black Siren will next attack City Hall, Team Arrow sets a trap. However, her gang instead attacks the hideout, but are driven off by Team Arrow. Quentin's reluctance to harm "Laurel" further allows her to escape. Oliver arranges another hearing for Rene to reclaim his daughter. Curtis discovers that Black Siren stole a prototype T-sphere. Slade tells Oliver that he is traveling to Calgary to find his son, advising him to choose between vigilantism and William. Oliver and William reconcile slightly, even as pictures of Oliver wearing the Green Arrow suit leak to the media.

Oliver publicly denies being the Green Arrow, facing an investigation by FBI agent Samanda Watson along with William's concerns of losing him. Anatoli and his men kidnap a group of Markovian delegates, demanding ransom. Believing Anatoli leaked the photo, Felicity and Curtis work on discrediting it while tracking the hostages, three of whom Team Arrow saves while Anatoli escapes with one. Anatoli tells Oliver that he needs to convince the Bratva that the former is not weak and is no longer friends with Oliver, injecting the hostage with a toxin which will kill him soon. Detecting the toxin and acquiring the antidote, Oliver injects it to the hostage, whom Anatoli kills anyway. He escapes after telling Oliver that he did not leak the photo, for which the media acquires evidence from an "anonymous source" that is fake. However, Watson tells Oliver that she will continue investigating him. As John prepares to tell Oliver about his degenerative nerve damage, the latter convinces him to wear the Green Arrow mantle, deciding to choose William over vigilantism.

Team Arrow arrests Faust, with John refusing to shoot arrows. The City Council begins drafting a tighter anti-vigilante bill. Telling Dinah that he has overcome his tremors, John is revealed to have leadership problems when rogue CIA operatives begin hunting down a former member in order to silence him. Rene asks Oliver to return to the team. The latter has Felicity help William with his mathematics test while convincing John of his competence. Team Arrow tracks down a rogue group of mercenaries led by Onyx Adams to a hotel and engages them, defeating them all and saving the civilians from a biological weapon. With no way to stop the bill, Oliver converts it to a city-wide referendum. Watson begins suspecting John, who receives an arrow-firing crossbow invented by Felicity and Curtis. Oliver resumes his relationship with her while John is revealed to be injecting drugs to control his tremors.

Black Siren begins killing seemingly unimportant individuals while Felicity is approached by Alena, who tells her that Cayden James is planning something with hundreds of millions of casualties worldwide. They meet black market dealer "Amnesiac" to buy a "ghost drive". Feeling concerned, Oliver intervenes and attacks the thugs, angering Felicity, who steals the drive. Team Arrow tracks down Black Siren to the Helix facility, with the former revealed to be working for James, who tasks his men to kill Felicity and Alena, who is critically shot during the rescue by Team Arrow. Felicity learns that James has stolen the victims' fingerprints, necessary to enter the International Domain Name Directory (IDND), the global internet infrastructure. Believing that James intends to destroy the internet, Team Arrow attacks his party at the IDND, where Felicity manages to breach through the firewall to stop James' apparent attack. She adds Alena for her startup, calling it Helix and intending to mass produce her spinal implant. James is revealed to have intentionally lured Felicity into breaking the firewall so that he can have secret access and cover his tracks. He provides Black Siren with a device to stop tracking by Curtis. Slade calls Oliver and asks his help.

Slade asks Oliver to help him find his son, who's being held in jail. The two meet up with an old acquaintance of Slade, who provides them with the information they need. When they get to the prison, Slade instructs Oliver to find his son, Joe, then get him out of there, as he knows Joe will not want to see him, despite Oliver's objections. Slade engages the security, known as the Jackals, in combat, where he discovers his acquaintance is actually a member of them. When Slade demands they release Joe, he reveals it's not that easy as their boss is Joe himself. Dinah struggles to prevent a politician from a sniper attack by Vigilante, as the politician supports the Anti-vigilante bill. Dinah later gets lucky, and blurts out her Canary Cry on Vigilante who removes his mask, revealing he is actually Dinah's old partner Vincent Sobel, thought long dead. He later attempts another assassination attempt at a TV interview, but is once again met by Dinah and shot in the head by an officer. Vincent reveals the Particle Accelerator changed him as well, and claims he didn't tell Dinah he was alive, as he believes their work as cops had become ineffective. Dinah watches helplessly as he disappears.

Slade and Oliver continue to try and persuade Joe to leave with them, but Joe refuses, claiming that he had seen his father kill someone before he had been influenced by Mirakuru. Slade tries to explain that it was a paid hit, but Joe refuses to forgive him, stating that learning who his father truly was led him down this path. Joe and Slade end up fighting until Oliver steps in, after which Joe escapes but not before revealing the existence of his brother Grant. Slade tells Oliver he will continue to try and find both of his sons, but advises Oliver that he go back to his, not wanting Oliver to make the same mistakes he made. Meanwhile, Team Arrow eventually finds out about John's tremors, leading John to apologize to everyone. Curtis offers to help John, the same way he helped Felicity when she was injured. John asks to have the night to think it over.

Oliver, Felicity, William and Quentin organize a Thanksgiving food drive to raise money for a new SCPD Precinct. Oliver is promptly arrested by FBI Agent Watson under charges of vigilantism for being the Green Arrow. James and Black Siren subsequently break out of prison, intent on causing chaos, since the Green Arrow is caught. Thankfully, Oliver's trial is delayed. When John gets injured in the field, Oliver suits up as the Green Arrow once again, with Team Arrow looking to stop a bomb planted by James and Black Siren at the stadium during a concert. They subsequently discover the bomb is fake and that the cops guarding the stadium aren't cops, whom are swiftly taken out by Dinah, Curtis and Rene, but James and Black Siren escape. Oliver visits John in hospital and claims he will wear the hood until John has recovered, whereupon he can reclaim it. Thea wakes from her coma and reunites with Oliver, Felicity, John and William.

In S.T.A.R. Labs, a captured interdimensional villain from Earth-X, Prometheus-X, is revealed to be a parallel universe doppelgänger of Tommy Merlyn. After he cruelly taunts Oliver over his attachment to Tommy, Prometheus-X commits suicide out of loyalty to Earth-X's Nazi regime. Prometheus-X's partners, Dark Arrow (Oliver's doppelgänger), Overgirl (Kara Danvers' doppelgänger), and Eobard Thawne steal a sublight generator, the Prism, from research company Dayton Optical Systems; Oliver, Barry, Kara, and the others believe that Dark Arrow seeks to build a neutron bomb with it to aid his conquest on Earth-1. After a series of battles, most of the heroes including Team Arrow are in captivity at S.T.A.R. Labs after the Nazi forces infiltrate it, and Oliver, Barry and his allies are transported to Earth-X's concentration camp, but Kara is moved to S.T.A.R. Labs. Oliver is determined to kill Dark Arrow after his capture. The villains reveal that Overgirl is dying and Dark Arrow plans to use the Prism, charged by S.T.A.R. Labs' particle accelerator, to produce artificial red sunlight that would weaken both Kara and Overgirl's respective invulnerability, allowing a heart transplant for Overgirl but killing Kara in the process.

This episode continues a crossover event that begins on Supergirl season 3 episode 8, and concludes on The Flash season 4 episode 8 and Legends of Tomorrow season 3 episode 8.

Oliver and Felicity celebrate their wedding with everyone. The case against Oliver intensifies when Quentin learns that a member of Team Arrow is testifying against him, causing Oliver to have the team tracked. Quentin is kidnapped by Black Siren and James. Dinah is discovered to be meeting with Vincent, and tensions grow in the team until Rene admits he is the one testifying against Oliver. He explains Watson cornered him with evidence that he is Wild Dog, and if he didn't testify, he would never be able to see his daughter again. Oliver briefly evicts Rene from the team, but the entire team puts aside any differences to rescue Quentin, whom Black Siren willingly allows to escape once they are outside. Oliver permanently ousts Rene for abandoning the primary mission to go looking for Lance on his own, violating Oliver's trust again. Rene is later reunited with his daughter, while Dinah and Curtis leave Team Arrow, unable to trust Oliver, John and Felicity. Through a hidden camera, Oliver, John and Felicity are shown being monitored by the cabal of James, his second in command Boots, Black Siren, Anatoli, Vincent and Ricardo Diaz.

Oliver continues being the Green Arrow while refusing to have Rene, Dinah, and Curtis help him, while Felicity and Curtis struggle to cure John of his tremors, in the process discovering that their hideout has been bugged forcing them to relocate to A.R.G.U.S. Oliver once again faces Cayden James, discovering that he has a cabal at his command. Dinah spends time with Vincent before discovering he has allied with Cayden James and attempts to arrest him before being overpowered. After his fight with Cayden James's Cabal, Oliver, Felicity, and John discover that in order to win, they need to bring the team back together. Oliver apologizes to Rene, Dinah and Curtis, but despite his apology, they refuse to return to the team. Instead, they decide to start their own team, with Oliver wishing them luck. Curtis shows Dinah and Rene their new hideout.

Cayden James attacks the city's critical Internet infrastructure, causing numerous casualties including police captain Frank Pike, before demanding ransom payment of $10 million dollars a day from Oliver to prevent a deadlier attack from happening. James reveals details of his vendetta against Oliver; a misfired arrow believed was from the Green Arrow killed his son Owen a year ago. However, Oliver knows that he is not responsible because he was in Hub City at the time, therefore there is another suspect. Vincent claims that he is undercover with James' cabal, and he gives Curtis, Rene, and Dinah some Intel. When one of James' attacks endangers William and his class during a fieldtrip, Oliver is forced to reveal to his son that he resumed being the Green Arrow when rescuing him. Oliver and Quentin set up safe zones for citizens following the attacks, eventually James' cabal targets them. Oliver and his former team put aside of their differences and stop James' party's attack on the safe zones' occupants. Despite William being hurt by Oliver's lies, Felicity helps William to see it was for good intentions and gets him to accept his father’s duty. Unable to find proof of his innocence before the deadline, Oliver gives into James' demands to buy time to find it.

Oliver is almost out of money to pay James; fearing he will detonate the bomb, Vince - who was infiltrated into James' organization, agrees to enter James' server room to download datas that could lead the teams to find where the bomb is locate. Despite being successful into transmitting the datas to Felicty, he is intentified as the traitor, caught and tortured by Anatoly. The location of the bomb is revealed, but Dinah, Curtis and Rene decide not to follow Oliver in order to save Vince, however Cayden James anticipated this and used Vince as a bait; Dinah is immobilized because of some rubble collapsing on top of her because of an explosion and she is forced to watch as Black Siren executes Vince. Lacking the men power, Green Arrow and Spartan are unable in retrieving the bomb before its moved to a new location, however they retrieve the proof that, Cayden claims, shows Green Arrow killing his son, which has been falsified using the same techology that was used to falsify the picture that exposed Oliver as the Green Arrow.

Cayden James threatens to set the bomb off at midnight. Alena and Felicity are able to decode the video of Oliver killing Cayden's son, proving it was someone else, and clearing Oliver. With help from Barry Allen, Oliver is able to delay James from leaving town by showing him the new evidence. James concludes that it was someone in his group who is behind it and asks for his former allies to be brought to him or he will set off the bomb. The team brings Laurel, Diaz and Anatoli to James, but Laurel says she was behind his son's death and her actions allow everyone but James to escape. Diaz approaches Cayden in custody, revealing himself as the person responsible for the death of his son and that he has the new police captain on his payroll, killing Cayden before he leaves. Cayden's flashbacks focus on his relationship with the group Helix, his son Owen Post and the arrest from A.R.G.U.S., upon which he discovers his son is murdered.

Dinah, Curtis and Rene analyse the latest place Laurel was seen and manage to determine that she was dragged away by somebody. It turns out Quentin took Laurel to a secure cabin to allow her to heal, which Thea eventually finds out and informs Oliver. Oliver demands the return of the city's money, which Laurel promises, if they get her out of the country. Curtis hacks the chip preventing John's tremors, allowing them to track down Oliver, John and Felicity and hence find Laurel, though Quentin refuses to let Dinah kill Laurel. The two teams fight, with Rene eventually getting injured, and Oliver throwing a device that prohibits Dinah's scream, allowing Laurel to incapacitate them with her own scream and escape. At the hospital, when John and Felicity come to see Rene, Curtis and Dinah turn them away, saying they want nothing to do with them anymore. At the edge of the city, Laurel begs a van driver to help her.

Laurel appears at City Hall, revealing her story about how she was kidnapped and held against her will. Oliver and Thea find out that Ricardo is keeping a hostage, which is revealed to be former Team Arrow member Roy Harper, prompting Thea to once again assume the mantel of Speedy to try and rescue Roy. Dinah, upon hearing of the situation, says she is willing to help out this once, but Oliver refuses, saying if she does not trust him, he does not trust her. Oliver and John eventually take on Ricardo and his minions, who escape, but they do manage to rescue Roy. Oliver goes to see Laurel, who claims she cannot change who she is, but she will try to be good, if Oliver gives her the space to do so, which Oliver agrees to. But when he leaves, Black Siren receives a message from Diaz and smiles, implying that she works with him. Roy and Thea spend an evening together, where they are observed by a woman who reports that the heir of Ra's al Ghul has been located.

Nyssa comes to Star City for Thea, claiming that a splinter group from the League of Assassins, The Thanatos Guild, led by a woman called Athena, are coming for her for the location of a map that Malcolm supposedly knew the location of. Thea reluctantly agrees to help Nyssa, but claims she is leaving afterward. Team Arrow eventually find the box containing the map and use mathematics to unlock it, only for the map to be blank when opened, but Felicity helps to reveal the hidden markers underneath and discovers that it contains locations to other Lazarus Pits. Dinah grows suspicious of her superior in the police, suspecting that she might be peddling Diaz's drugs. Thea talks to Oliver about handing the Green Arrow mantle back to John, but Oliver worries that the current circumstances may be a little too much for John at the moment. Thea, Roy and Nyssa eventually depart to destroy the Lazarus Pits and Oliver says goodbye.

Dinah has Anatoli arrested but Captain Hill and DA Sam Armand force his release. Oliver confronts them with proof that they are working for Diaz and fires them when they affirm that they cannot accept his protection when faced with the threat posed by Diaz. Oliver apologizes to John about not giving him the suit, but after John questions his leadership skills and motives for continuing as the Green Arrow while Oliver counters that he has accepted his past mistakes, the two engage in an argument that leads to a fight. With Diaz pushing Vertigo through the city, Oliver and John work to destroy the shipment, while Curtis reveals his alter-ego to his new boyfriend, Nick Anastas. John decides to leave the team following the fight, leaving Oliver and Felicity as the final two members. Hill fires Dinah and the rest of the clean cops, forcing Nick to realize that vigilantism is the only path forward. Armand claims that Oliver obstructed justice, which is grounds for impeachment. Laurel learns that Diaz has one more vial of Vertigo and kisses him.

With Oliver's impeachment hearing beginning, he lashes out at Felicity and William, causing the former to request a separation. Oliver realizes he has been dosed with Vertigo, and he begins hallucinating Adrian Chase, who torments him with reminders of his past failures. Oliver realizes that he never should have formed a Team Arrow, allowing his loved ones to make him forget about his original mission. Learning Diaz's location, Oliver dons his original hood and attempts to take on the corrupt officers by himself. Felicity is able to bring Oliver back to his senses, revealing she never requested a separation. Oliver and Felicity escape before Diaz and his men can shoot them. Later, Oliver and William reconcile. Oliver is impeached, and Quentin becomes the new Mayor of Star City. Diaz tells Laurel that since Oliver has been impeached, it is time to inform crime families across the country that Star City is open for business.

A younger Diaz is shown in an orphanage being harassed by a bully. In the present, Diaz starts the next phase of his plan which is to join a criminal organization called The Quadrant. But one of the four leaders of the group doesn't think that Diaz is worthy enough, thinking of him as a street thug, and tries to have his son kill him. With Laurel's help, he wages a small war on the group, killing both the man and his son, then taking his seat at the table. Later on, Diaz tracks down the man who bullied him as a child, and sets him on fire as Laurel watches uncomfortably. Meanwhile, Felicity & Curtis work together again on their Helix project, while Oliver works alone in Star City. An explosion happens as Oliver is fighting Diaz's men, leaving no survivors. Felicity fearing for Oliver's life returns home to find him safe and sound, who promises her that he will never leave her.

Oliver pays a debt to Anatoli's rival in Russia, so that Anatoli will be able to go home. Oliver appeals to him, reminding him of his honor and their friendship. Anatoli betrays him, chains him, and later on takes him to see Diaz. Convinced to fight fairly by Anatoli, Diaz and Oliver square off one on one, with the loser to leave the city. Oliver bests Diaz, only for him to stab him with a knife. Later on, Diaz tells Oliver he's having his trial moved up and has him arrested. Meanwhile, Rene returns home, but is still affected by when he was shot. Dinah and Curtis team up with John and A.R.G.U.S. to stop a shipment of weapons by The Quadrant and are successful. As the new mayor, Quentin is approached by Diaz to sign a paper that will grant him some property in the city. Quentin refuses at first, but he eventually changes his mind out of fear for Laurel's safety after she expresses concerns about how dangerous he is.

Several witnesses are called at Oliver's trial to testify about the identity of the Green Arrow including John, Dinah, Dr. Schwartz, Rene, and Felicity. Diaz coerces Rene into saying Oliver is the Green Arrow at trial by threatening his daughter in front of him. After Oliver takes the stand, the Green Arrow crashes through the skylight, revealing himself to be Tommy Merlyn back from the dead. Tommy testifies that he is really the Arrow and is taken into custody. When being saved from Diaz's men by John and Rene, he is revealed to be Christopher Chance, the Human Target. Laurel takes the stand and, despite being threatened by Diaz earlier, testifies that Tommy is the real Green Arrow. Oliver is found guilty, proving the assumption that both the judge and the jury were in Diaz's pocket. Oliver's lawyer moves for a judgment notwithstanding verdict and the judge surprisingly agrees. Oliver returns to the lair and discovers that Chance switched places with the judge during jury deliberation. Oliver and Rene reconcile. Diaz kills the real judge just before Laurel appears and attacks him and his men, momentarily downing Diaz, before he takes her captive, telling her that he plans to kill Oliver and everyone he cares about.

Diaz orchestrates attacks against Team Arrow and their loved ones; most escape unscathed but Curtis's boyfriend Nick is seriously injured. They reunite at the New Team Arrow's bunker where they watch as Diaz' men destroy Original Team Arrow's bunker. With Anatoli's help, Oliver ambushes Diaz, but he escapes, severely wounding Curtis. The team realizes Diaz was protecting a device containing potentially important data, and send Lyla into the SCPD headquarters to hack it. Felicity discovers it is an encrypted list of everyone on Diaz's payroll and starts attempting to decode it. Diaz kills one of the Quadrant leaders, assuming she gave Team Arrow the intel about his convoy. He attacks the new bunker, fights with and nearly kills Oliver, who triggers explosives installed as a fail-safe against intruders. He and Felicity escape, but the still-encrypted data is lost. Diaz meets with the remaining two Quadrant leaders, kills one and makes the other accept him as the head of the organization. Oliver turns to Agent Watson for help; she agrees provided he admits to her that he is the Green Arrow.

Team Arrow mount a final attack on Diaz and while Diaz manages to escape, Oliver obtains the list of everyone on his payroll, liberating Star City. During the attack, Quentin takes a bullet for Laurel and ends up in the hospital. The team comes to support him, including Laurel and a surprise visit from Sara. However, Quentin suffers a seizure during surgery and dies. Oliver manages to get the team immunity from the FBI and police in exchange for handing himself in. Agent Watson promises the team that the FBI will stay in Star City to deal with Diaz, before arresting Oliver. Oliver finally admits to the public that he is the Green Arrow, and urges his friends and allies to continue fighting to save the city. In prison, Oliver walks to his cell, with criminals acting violently towards him now that they know he is the Green Arrow.

Five months after being exposed as Green Arrow and into his sentence, Oliver tries to maintain a low profile in prison in hopes of getting a reduction to his term, an effort which is complicated when Brick tries to coerce Oliver into helping him and being stalked by Diaz's associates. Meanwhile, Felicity and William try to cope with witness protection while Diggle and A.R.G.U.S. continue hunting Diaz. Back in Star City, a new vigilante archer appears on the scene, dismantling arms trafficker Jason Stent's operations and targeting other criminals on his list. The archer also steals money from his targets to help the city's poor. Rene, despite not knowing who the archer is, decides to trust him after being helped by the vigilante. The rest of Team Arrow do not trust the archer, and Dinah is determined to arrest him. Because of the archer's tactics, skills, and appearance parallel Oliver's suited persona's, the media in times dubs him as the new Green Arrow. After being discovered by Diaz, Felicity leaves witness protection to help capture him. In a flashforward, set twenty years in the future, William seeks out the help of Roy Harper on Lian Yu.

The Longbow Hunters arrive in Star City and the team works together with A.R.G.U.S. to try and stop them from stealing a weapon with incredible destructive capabilities. Felicity and Diggle clash over their priorities in dealing with Diaz, leading Felicity to strike a deal with Agent Watson. Meanwhile, Laurel and Dinah are forced to put their feud aside and work together while Oliver tries to get rid of a prison guard in exchange for info on Diaz from Brick. In the flashforward, William and Roy find a clue hidden in Oliver's bow which leads them back to Star City.

Oliver demands Brick honor their deal and Brick says an inmate known as "The Demon" is Diaz's inside man. Brick claims to arrange a meet with the Demon but Oliver is instead ambushed. After defeating Brick's hired men, Brick reveals the Demon is incarcerated on Level Two, prompting Oliver to attack a guard to get transferred there. Meanwhile, Felicity plans a trap for Diaz and the Longbow Hunters at the CDC along with Rene and Dinah. The plan fails and Agent Watson is transferred but it is revealed that Rene and Felicity captured Silencer, one of the Longbow Hunters. Elsewhere, Diggle discovers Lyla has been keeping a secret when they and Curtis go on a mission in Zurich.

In prison, Oliver is tortured both psychologically and with the use of drugs and other electrical devices, with the intent of "reprogramming" his brain. In Star City, Dinah arrests Rene when she learns that he is providing support to the new Green Arrow, but when the vigilante saves Zoe's life, she begins to trust him. Working together, Dinah, Rene and the vigilante are able to capture the arsonists. Elsewhere, Felicity enlists the help of Laurel to torture the Silencer for information on Diaz, but to no avail. Felicity allows her to escape in the hope that she will lead them to Diaz, having planted a bug into her belt. In the flashforward, William and Roy are in Star City, the coordinates change leading them to what remains of Smoak Industries. William solves a puzzle and obtains a Rubik's Cube; he and Roy are attacked by the police but rescued by Dinah who leads them to safety where they meet an adult Zoe. After William solves the second puzzle, Dinah claims that Felicity is dead.

After having seemingly been broken, Oliver is introduced to Level Two, a secret facility below Slabside, where inmates are kept in inhuman conditions and mostly experimented on. He discovers that Talia al Ghul is the Demon. He reluctantly teams up with Talia to plan an escape, however, he decides not to escape himself to avoid having to spend the rest of his life as a fugitive. After collecting evidence of what happened in Level Two, he asks Talia to deliver them to Felicity, which she does, thus causing the facility to be shut down and Oliver transferred back to Level One. Elsewhere, Curtis gets back in the field with Diggle, and helps capturing an international terrorist. Laurel plans to use the evidence that Oliver collected to plead for his release.

Diaz slaughters the Bratva and tortures Anatoly in order to get in contact with one of his KGB associates. Team Arrow rescues Anatoly and discover that Diaz plans to level Star City with aerial explosives obtained from the associate. Team Arrow foils the plan and captures Diaz with help from the new Green Arrow. Meanwhile in Slabside, Stanley is accused of murdering a guard, but proclaims his innocence. Oliver finds the knife used in the attack with Brick associate Ben Turner's fingerprints on it. Released from solitary confinement, Stanley thanks Oliver but inadvertently reveals knowing that the knife belonged to Turner, information he could not have gotten in the hole. At SCPD, Laurel orchestrates a deal which will see Oliver walk out of prison in exchange for helping the FBI with their case against Diaz. In the flash-forward, William and Roy learn that before her apparent death, Felicity had become a criminal, taking on her father's mantle as the Calculator. The two, along with Dinah and Zoe, find Felicity's plans for the destruction of Star City.

Oliver is told that he is set to released from prison. Oliver confronts Stanley about him framing Turner for the guard's murder and then visits Turner, promising to help him once he is out of prison. Diaz arrives at Slabside on prisoner transport, but bribes a guard to release him and then visits Oliver, threatening to kill him and his family. After guards refuse to take his warnings about Diaz seriously, Oliver breaks out of his cell and escapes level one in order to contact Team Arrow. Diaz cuts communications from the prison, preventing Oliver from getting outside help, and releases all prisoners, starting a riot. Turner turns on Brick and Derek Sampson and helps Oliver get to a final showdown with Diaz. Sampson is killed in a fire. During their fight, Oliver stabs Diaz in his cell and locks him in it. Elsewhere, Stanley kills Brick and escapes. Oliver is finally set free from prison and reunites with Felicity and John.

Now free from prison, Oliver tries to readjust to outside life. When a murder occurs at a party honoring Oliver, the new Green Arrow is suspected and Oliver, Dinah and Rene set out to prove the vigilante's innocence. Meanwhile, Oliver and Felicity struggle to adjust to the changes Oliver's incarceration inflicted upon their lives and relationship. Ultimately, Dinah authorizes Oliver to work with the SCPD as a special deputy in order to avoid the anti-vigilante law and the new Green Arrow is revealed to be Oliver's half-sister, from a previous relationship of Robert Queen's. Diggle and Lyla find out the Longbow Hunters are up to something and, unbeknownst to Team Arrow, pay Diaz a visit in prison to request his assistance. In the flash-forward, Dinah, William and Zoe track down a woman known as Blackstar, who had ties to Felicity's plans.

Oliver, Barry Allen, and Kara Danvers head to Gotham City to find John Deegan, but are quickly arrested. However, they are bailed out by Kate Kane, who tells them Deegan can be found at Arkham Asylum. With some assistance from Oliver and Barry's teams, they break in to confront Deegan and retrieve the book he used to rewrite reality; only for the doctor to escape and cause a mass breakout. While trying to contain it, Batwoman shows up to help them before telling them to leave Gotham. Returning to A.R.G.U.S., the heroes attempt to unlock the book when the Flash of Earth-90 breaches through to them and warns them of the Monitor. Oliver, Barry, Kara, and Earth-90's Flash go to confront Monitor, but the omnipotent being escapes and returns the book to Deegan; who changes reality once more. This time, Oliver and Barry wake up as wanted criminals and are forced to contend with both police and a black-suited Superman.

Oliver discovers blood belonging to the new Green Arrow with Felicity determining that it belongs to a woman named Emiko Queen, who is Oliver's father's illegitimate daughter and thus his paternal half-sister. Oliver goes through his father's belongings and discovers that his mother knew about Emiko and her mother Kazumi Adachi. After being injured, Emiko goes to Rene for help and reveals that she seeks to avenge her mother's murder in the Glades. Emiko visits her father's grave, where she is confronted by Oliver. Meanwhile, in order to be able to work without A.R.G.U.S. oversight, Diggle and Lyla restore the Suicide Squad as the Ghost Initiative, recruiting Diaz as its first member and implanting an explosive into his neck to ensure his compliance in tracking down terrorist financier Dante. In the flashforwards, Dinah confronts Rene, who is now the mayor of the Glades, which is thriving thanks to a security program called Archer, and forces him to help her. Later Rene meets with someone who is linked to the bomb plans, explicitly stating that their plans to build up the Glades will sacrifice the rest of the city.

Felicity and Laurel work together tracking down a person Laurel believes may have followed her from Earth-2. The person is eventually revealed as the Earth-1 version of the drunk Brett Collins who accidentally killed Laurel's father. The Earth-2 version of Brett is revealed to have died five years earlier. Diaz attempts a mass breakout from A.R.G.U.S., killing Curtis in the process, before it is revealed he was in a controlled virtual reality simulation brought on by Curtis to extract information regarding Dante. The SCPD is held hostage by a suicide bomber using electricity, who reveals himself to be Sam Hackett, the son of Dave Hackett from the Queen's Gambit, whom Robert killed so Oliver could survive. Sam wants Oliver dead, forcing the officers to either kill him or die. Oliver reasons with Sam long enough for Dinah to cut the power, removing his powers and allowing Oliver to apprehend him. Emiko starts to see the good in Oliver and thinks about starting to talk. Dinah reads a note from an unknown source stating that someone will kill the vigilantes one by one.

Oliver allows a camera crew to follow himself and others associated to Team Arrow around and film a documentary titled The Hood and the Rise of Vigilantes. A new vigilante, named Chimera by Curtis, begins attacking vigilantes in Star City, among those being Ragman, Huntress, and the new Green Arrow. William returns from witness protection and tells Felicity he was expelled from the school he had been sent to, while Oliver debates Mayor Pollard about vigilantism but is interrupted by Chimera. During the attack, Dinah saves Pollard using her Canary Cry which reveals her identity as the Black Canary. When Team Arrow arrive and help Oliver capture Chimera, Pollard arrests them prompting Oliver and Dinah to turn themselves in, resulting in Pollard deputizing Team Arrow as part of the SCPD. In flashforwards, it is shown that Blackstar is watching the documentary on Oliver. With intel gained from the documentary, Blackstar and Connor Hawke find the destroyed Team Arrow bunker.

Members of Team Arrow receive threatening notes and discover a similar note at the murder scene of a councilman who previously worked with Ricardo Diaz. Tracking a drug used to immobilize the victim, they discover the hiding place of the "Star City Slayer", who is revealed as Stanley. He slits Dinah's throat, but Curtis cauterizes the wound, saving her life. Stanley confronts Oliver, Felicity and William at their apartment, claiming to be the only one who truly understands Oliver. While Felicity distracts Stanley, Oliver subdues him and he is sent back to Slabside. William, wanting a normal life, chooses to go live with his grandparents. Curtis accepts a job in Washington, D.C., and leaves Star City, signing sole ownership of their Helix company over to Felicity. Meanwhile, a medical checkup discovers something important about Felicity. In flashforwards, Dinah, Roy, William and Zoe find the Arrow bunker and get into a fight with Blackstar and Connor Hawke. Blackstar claims that Felicity is alive before revealing that she is Mia Smoak, the daughter of Oliver and Felicity, and William's half-sister.

Felicity and Laurel continue growing closer with Felicity revealing to her that she is pregnant with Oliver's child. John and Lyla successfully locate Dante with the Ghost Initiative, identifying A.R.G.U.S. Director Bell as the mole, but during the operation to catch him, Diaz betrays the team to warn Dante, who escapes, killing Bell and potential client, Quraci Princess Noor, in the process. Diaz is taken back to Slabside, where an unseen assailant lights him on fire in his cell, killing him. With the Ghost Initiative exposed, John takes the fall for his wife and hands in his resignation. Oliver and Rene work together with Emiko to find out who killed her mother. In her hideout, Emiko meets Dante; revealing they are working together. In the flashforwards, Mia and William start working together to locate Felicity.

Team Arrow works with the SCPD to take down an operation that is manufacturing poison bullets. When the initial attempt as part of the SCPD fails, Team Arrow goes rogue and successfully takes down the operation as vigilantes, resulting in Mayor Pollard creating a special vigilante task force, sanctioned by the SCPD and made up of Team Arrow. Dinah, who can no longer fully perform the Canary Cry following her injury, decides to return to the field as part of the task force. Laurel visits Slabside, where Ben Turner tells her that he witnessed the new Green Arrow kill Diaz. Laurel confronts Emiko, who states that no one would believe Black Siren, a former criminal. In the flashforwards, Mia and William obtain a recorder and play a tape from Felicity, where she gives coordinates to the other members of the team. The two ignore Felicity's orders to leave Star City and instead follow the coordinates to the Glades.

In the flashforwards, Mia and William follow Felicity's coordinates to Galaxy One headquarters. They are almost caught, but are saved by Connor, who reveals himself as an agent of Knightwatch, a "good version of A.R.G.U.S." Meanwhile, Rene confronts Dinah, Roy and Zoe and reveals that Galaxy One plans to blow up Star City to rebuild it like the Glades, claiming that the city will be evacuated beforehand. The three discover that a terrorist organization named Eden Corps, who use Galaxy One as a front, paid SCPD to fake Felicity's death. Mia, William and Connor enter the headquarters' sublevels, where they find an imprisoned Felicity, who claims that the building houses the bombs to be used in Star City. The others reunite with the group, before they meet Rene, who has learned that the bombs are already on-site and that there are no plans to evacuate. The group infiltrates a party, where Mia destroys an electronic device held by Galaxy One head Keven Dale that disables the bombs. Dale unveils a helmet that would enable Galaxy One to take the Archer program global. Felicity makes amends with Mia, stating that her grudge with Galaxy One is personal. In the present, Felicity activates Archer.

Laurel tells Oliver about Emiko killing Diaz. Oliver finds Emiko and Dante stealing drones and confronts Emiko, who states that she owes Dante and the Ninth Circle for helping her when she was abandoned by her father. Using Archer, Team Arrow locates Dante and when he seemingly believes Emiko has betrayed him, Oliver saves her and takes her back to the Arrow bunker. However, she escapes after being caught planting a jammer, which takes down Archer and allows the Ninth Circle to steal Sarin gas. Team Arrow tracks the Sarin drones to an airfield, where Oliver disables all but one of them, which gets away thanks to Emiko and releases the gas over an abandoned building. Emiko is revealed as the leader of the Ninth Circle and tells Dante about Archer. She also frames Laurel for killing an SCPD witness while releasing photos of her with Diaz to the press. Meanwhile, Felicity founds Smoak Technologies and hires Alena Whitlock as her CTO. Flashbacks show Emiko being abandoned by her father and meeting Dante. As an adult, she goes to her father for business help, but gets turned down, which leads to her staying silent about the explosives on board the Queen's Gambit.

Laurel goes on the run and partners up with a former associate named Shadow Thief. Felicity discovers that Emiko framed Laurel, but Dinah informs her that Laurel has gone back to committing crime as Black Siren. After failing to convince Laurel to come back, Felicity recruits Sara Lance to come to her and Dinah's aid. The three confront Laurel about what she wants to be, which leads to her turning on Shadow Thief. Dinah clears Laurel's reputation by claiming she went undercover. Laurel decides to return to Earth-2 to right her wrongs as Black Canary. Meanwhile, Oliver and Diggle track the rifle used to kill Emiko's mother and discover it belongs to Kodiak of the Longbow Hunters. Through interrogation, they find out he was hired by Dante. In the flashforwards, Galaxy One unleashes Zeta, a new force hunting down the Canary Network with a tech helmet powered by the Archer program. While the others want to hide, Mia wants to fight back and ambushes one of the Zetas. Mia is overpowered, but is saved by Laurel, who tells her to give the Zeta's helmet to Felicity.

With the Ninth Circle after a Department of Defense vault drive, Diggle contacts his stepfather, General Roy Stewart, but Stewart refuses to give classified intel. After they steal Archer from Smoak Tech, Stewart reveals the drive contains an asset list the Ninth Circle can now track. While securing the assets, Diggle and Stewart are captured by Dante. Stewart surrenders codes for a biological weapon called Cygnus X-1 when Dante starts torturing Diggle. The two call in Team Arrow with the Spartan helmet and escape. Team Arrow tracks Archer and the Ninth Circle to Cygnus X-1. While the rest destroy Archer, Oliver confronts Emiko, telling her Dante had her mother killed. Dante exfiltrates Emiko and they escape with Cygnus X-1, after which Emiko kills Dante. Diggle makes amends with Stewart after learning he is blameless in his father's death. Alena copied Archer's root code and suggests a partnership with Magnus Labs to expand it, but Felicity refuses to rebuild it. In the flashforwards, Mia and Connor obtain a power module for the tech helmet from the Deathstroke gang, led by Connor's adoptive brother J.J., but are afterwards attacked by them. Felicity powers up the helmet and learns Galaxy One has expanded Archer.

Dinah and Sergeant Bingsley interrogate Team Arrow, who are in SCPD custody accused of killing two subway station security guards. They reveal recruiting Roy Harper to help with an operation where they successfully prevented the Ninth Circle from releasing their biological weapon. After Oliver names Emiko as the killer, the team is released with their stories lining up. It is revealed that they all lied and that Dinah was part of the operation, and that Roy killed the guards in a fit of rage. The team decides to protect Roy, in order to save the team and be able to continue hunting the Ninth Circle. Oliver recognizes the bloodlust he witnessed and meets a remorseful Roy, who reveals that he died battling the Thanatos Guild and was then revived by Thea Queen and Nyssa al Ghul with a Lazarus Pit. Felicity locates the Ninth Circle's headquarters, where Oliver confronts Emiko, who reveals she has sent the subway station security footage to Bingsley. Emiko comes clean about her role in Robert Queen's death and states that her goal is to destroy Oliver's legacy while he dies a villain like their father. Emiko blows up the building, burying Oliver.

Oliver is trapped one floor below his team. The physical and psychological trauma causes him to hallucinate Tommy Merlyn talking to him about how to deal with Emiko. Oliver refuses to listen to Tommy about using the best parts of himself to save her until he envisions a scenario where his vendetta against Emiko leads to the deaths of his teammates. Team Arrow locate Oliver and save him. Meanwhile, the SCPD raid Smoak Tech, accusing Team Arrow of both the cover-up and the biological weapon, which was traced to Archer. Felicity and Alena escape to the bunker, where they are confronted by Emiko, who leaves after Felicity reveals she is pregnant. Emiko is revealed to have stolen Oliver's arrows and attacks the SCPD as the Green Arrow, stealing the weapon back. Oliver tries to reason with Emiko and refuses to take the opportunity to kill her, allowing her to escape. In the flashforwards, the group set out to destroy Archer with Felicity contacting Alena, who stole the program and sold it to Galaxy One. William returns to Galaxy One headquarters to steal Archer's root code, but he and Rene are caught. Galaxy One enters the hideout to arrest the others.

Emiko spreads the virus throughout the city and holds the detonator in the former Queen Consolidated building. Team Arrow, with Curtis, Laurel, and Ben Turner, evacuate it and disable the relay to other bombs, while Oliver confronts Emiko, pleading her to abandon the dark path. Beatrice informs Emiko that her failure to destroy Star City, while publicly exposing the Ninth Circle, has led to the council turning on her. Oliver and Emiko fight the Ninth Circle together, but Emiko is mortally wounded by Beatrice and tells Oliver to hide Felicity and their baby, before he escapes the exploding building. Oliver and Felicity invent the Mark of Four before leaving Star City for Bloomfield. Following Mia's birth, the Monitor appears, demanding Oliver to hold up his part of their deal.[a] Oliver leaves with him to assist in the oncoming crisis, despite learning he will die in it. In the flashforwards, Connor and Zoe save the others. Felicity creates a computer virus that Mia and William upload to destroy Archer. The older generation leaves the younger in charge of protecting the city. After a moment with her children at Oliver's grave, Felicity leaves with the Monitor to reunite with Oliver at a place of no return.

Mar Novu / The Monitor sends Oliver Queen to Earth-2 to retrieve Dwarf Star particles, but they are stolen by this Earth's Tommy Merlyn, who is looking to use them to level the Glades with his own version of the "Undertaking". Oliver joins forces with Earth-1 John Diggle as well as Earth-2's Laurel Lance and Adrian Chase to stop Tommy and retrieve the particles. Just as Oliver and Diggle are about to leave, an anti-matter wave suddenly consumes all of Earth-2, barely giving them and Laurel time to escape to Earth-1. In the 2040 flashforwards, Connor Hawke, Mia Smoak, William Clayton, and Zoe Ramirez encounter the Deathstroke Gang, led by Connor's adoptive brother John Diggle "J.J." Jr., who have grown more powerful since the destruction of the wall between Star City and the Glades.

The Monitor brings Oliver's party to Hong Kong to pick up biophysicist Robert Wong, who was forced to recreate the Alpha/Omega Virus. However, Laurel storms off to get her breach device fixed. While Oliver and Diggle learn more about Wong, Triad members attack them, though Tatsu Yamashiro comes to their aid and reveals she knows of the Monitor. Oliver locates Wong, only for China White to kidnap him. After obtaining a sample of the Alpha/Omega Virus, Oliver arranges a trade with China. While Oliver rescues Wong, Tatsu engages China, who stabs her before Laurel blasts her away. After talking with Tatsu, Oliver plans to get more answers about the Monitor at Nanda Parbat. Elsewhere, Lyla Michaels is revealed to be working with the Monitor as she delivers Wong to him. In the flashforwards, William works on repairing a device obtained from the Deathstroke Gang while Mia, Connor, and Zoe head to a black market where J.J. plans to make a sale. When the Deathstroke Gang arrives, Connor and J.J. enter a parley, though the former's group is forced to let the latter leave when he reveals that he had his men raid the bunker.

Oliver heads to Nanda Parbat to gain more information on the Monitor from Talia al Ghul, where he reunites with his sister Thea and fills her in on his impending death. Oliver, Thea, and Talia plan to retrieve an ancient textbook, but are ambushed by Athena and the League of Assassins. The trio narrowly manage to escape and eventually find the book; learning that the Monitor may actually be causing the oncoming crisis rather than preventing it. Meanwhile, Diggle and Lyla track down Farzad Qadir, who is holding a mother and son captive. As the two free the captives and kill Qadir in the process, Diggle learns that the boy's name is Connor. In the flash-forwards, William managed to escape from the Deathstroke Gang through a trapdoor in the bunker. He discovers their next plan, but it is interrupted by Mia, Connor, and Zoe. J.J. defeats Mia, but when Zoe attacks him, he kills her. Connor beats J.J. down in a rage, but before he can kill him, Connor, William, and Mia are mysteriously teleported to the bunker in the year 2019 where they meet Oliver, Dinah, Rene, and Diggle.

Future and present Team Arrow meet without knowing how the former traveled to the present. Mia and Connor choose to keep details of their time a secret from the others, but William anticipates that they will soon become suspicious. Meanwhile, Grant Wilson leads an army as the new Deathstroke to destroy Star City. After Mia and Connor mistake Grant for a time-displaced J.J., they are confronted by present Team Arrow. William and Connor admit what happens in their time; including how J.J. becomes Grant's successor and murders Zoe. Diggle and Rene are left devastated yet determined to change their respective children's fates. The two teams work together to stop Grant, and he is arrested. Curtis Holt tells Oliver that the Russian Armed Forces have schematics and components to build an anti-matter weapon. Diggle reconciles with Connor. Laurel and Dinah, intrigued by their future selves' actions, make plans to form the Canaries earlier than expected. Rene begins his campaign in the Glades. Oliver begins to be a father to Mia. Later that night, the Monitor makes a deal with Laurel; promising to restore Earth-2 if she betrays Oliver.

Oliver learns that their next target is Russian general Alexi Burov, who is working on a pulse wave generator weapon that requires plutonium. Oliver takes William, Mia and Laurel to steal the weapon plans. Laurel discovers that Lyla is working with the Monitor, who she also agrees to work with by stealing the weapon plans before Oliver. Oliver seeks assistance from Anatoly Knyazev to lead him to Burov, who explains he had abandoned the plans, though he has them stored on a hard drive. Burov requests a trade - a cage match for the drive in the Bloodbath, which Oliver accepts. Afterwards, the Bratva led by Oleg intervene and fatally shoot Burov before taking the team captive until Laurel and Anatoly come to free them with William's help. The team then successfully retrieve the drive and celebrate their victory before returning to Star City. Meanwhile, Diggle recruits a reluctant Roy Harper on a heist for plutonium. Following the heist, Roy decides to stay in Star City to help the team against the Monitor. Later that night, Laurel declines Lyla's offer to join her mission as Oliver and Diggle discover Lyla's betrayal, only to get tranquilized.

Upon waking, Oliver finds a living Quentin Lance as mayor at a party. When mercenaries take the SCPD hostage demanding to speak to Quentin, he agrees to their terms while Oliver defeats them; only for the leader to set off a bomb. Oliver awakens in his apartment again learning he's re-living the same day. When he discovers Laurel is also experiencing this, they realize the Monitor set this up. Following the third reset, they conclude attempting to stop the bomb results in Quentin's death which causes the reset. On number four, Lyla tells Oliver he is missing the point and shoots Quentin. On number five, Laurel says goodbye to Quentin. On the sixth reset, Lyla informs Oliver Laurel's gone and that he needs to learn to accept the inevitable for everything to end. After a talk with Quentin, Oliver goes through one more reset and allows Quentin to meet his fate. Afterwards, Lyla states that he has passed the Monitor's test by allowing Quentin to have his final moments and reveals the Monitor brought William, Mia, and Connor to the present. Oliver and Laurel wake up on Lian Yu alongside Diggle, William, Mia, and Connor.

The team learns that Lian Yu has been giving off an immense amount of strange energy and Lyla tasks William with creating a device to harness it, while the plutonium is being transported by Dinah, Rene and Roy. Upon arrival, their plane is shot down by a missile and crash lands on the island. Diggle, Lyla, and Connor rescue Dinah and Rene, while Oliver and Laurel retrieve the plutonium. However, they are confronted by Edward Fyers, Billy Wintergreen and Yao Fei - deceased figures from Oliver's past who were all revived by the island's supernatural energy. Meanwhile, Diggle's party finds Roy, whose right arm is pinned; forcing Connor to amputate him, after William completes the weapon, Lyla activates it and transforms; absorbing the island's energy and causing it's revived inhabitants to disappear before entering a portal. She later returns, now calling herself a "harbinger of things to come", and informs Oliver and Mia that the Crisis has begun as the sky turns red.

In a flashback to the planet Maltus 10,000 years ago, Mar Novu experiments with time travel to see the dawn of time, only to accidentally end up in the anti-matter universe and unleash the Anti-Monitor. Following the multiverse's destruction, the Paragons attempt to find a way out of the Vanishing Point and save the multiverse. With Jim Corrigan's help, Oliver learns how to use the Spectre's power so he can rescue the Paragons and strengthen Barry Allen's powers. With his increased speed, Barry drops off Kara Danvers, Ryan Choi, and Lex Luthor on Maltus to stop Novu, but gets attacked by the Anti-Monitor and loses the others across the Speed Force. Though Kara's team successfully stop Novu and Barry retrieves everyone, upon reaching the dawn of time they learn the Anti-Monitor was released regardless. With Oliver's help, the Paragons engage the god-like being and his shadow demons, holding him off long enough for Oliver to combine the Spectre's power with the Book of Destiny to reboot the multiverse. Despite succeeding, Oliver dies a second and final time in Barry and Sara's arms.

This episode continues a crossover event that begins on Supergirl season 5 episode 9, Batwoman season 1 episode 9, and The Flash season 6 episode 9, and concludes on Legends of Tomorrow's special episode.

In 2040, two decades after Oliver's sacrifice saved the universe, crime in Star City has been quiet, Mia has led a successful life with her fiancé J.J., and Zoe is alive. When Helena Bertinelli's daughter Bianca goes missing, Laurel requests Dinah's help in finding her. She then recruits a reluctant Mia, restoring her pre-Crisis memories with Martian technology developed by Cisco Ramon, and manages to convince her to take on the mantle of Green Arrow. Mia, Dinah, and Laurel rescue Bianca from the captivity of her ex-boyfriend Trevor, possessing a Deathstroke mask. Just as Mia learns that he is working for someone else, Trevor sets off the gas line and escapes. Afterwards, Dinah decides to establish the Canary Network. At Oliver's memorial, Mia recognizes the hõzen that William was given as a teenager as a tattoo on Trevor's hand before being tranquilized by masked men who make off with William and leave Mia behind. Elsewhere at the same time, a mysterious figure ambushes J.J. and uses the same Martian technology to restore his pre-Crisis memories, telling J.J that he "needs him".

The episode serves as a backdoor pilot for a potential spin-off series titled Green Arrow and the Canaries, starring Katherine McNamara, Katie Cassidy, and Juliana Harkavy.

In flashbacks to 2012, Oliver and Diggle track and imprison human trafficker John Byrne, a man on Oliver's list. A flashback to 2014 depicts Oliver stopping Slade Wilson from killing his mother. In 2040, Sara Lance invites Mia to Oliver's funeral. In the present, following Oliver's sacrifice while averting the Crisis, Byrne abducts the younger William. Felicity Smoak and Rory Regan return to assist in the search. Amidst said search, Roy proposes to Thea, who accepts. Mia rescues William, spares Byrne, and takes him to prison. Diggle and Lyla agree to move to Metropolis, Dinah declines a promotion, and Rene continues being a mayoral candidate. Oliver's friends and family host a private funeral for him. Alongside Anatoly, Barry, Curtis, Dinah, Felicity, Kara, Laurel, Lyla, Mia, Nyssa al Ghul, Rene, Rory, Roy, Sara, Talia, Thea, William, and a revived Tommy, Moira, Quentin and Emiko. Emiko meets Thea and Moira for the first time and is welcomed to the family. Tommy reveals to Laurel he was married to her Earth-Prime counterpart in this timeline. Felicity meets the future Mia. Later, Diggle witnesses a meteor crash and finds a box containing an object emitting a green light. In 2040, the Monitor takes Felicity to see Oliver in the afterlife, where he has finally found peace.

Three years after the disappearance of Gotham City-based vigilante Batman, Jacob Kane and his private security firm the Crows preside over a gala led by Mayor Michael Akins to turn off the Bat-Signal. At the height of the festivities, Alice and the Wonderland Gang crash the event and abduct Crows operative Sophie Moore, prompting Jacob's stepdaughter Mary to call his biological daughter, Kate. Returning from overseas, Kate learns Alice is targeting her father and sets out to locate her cousin, billionaire Bruce Wayne. She discovers, however, that Bruce is Batman, who she blamed for failing to save her sister and mother after they died in a car crash. Realizing there's more to the story, she dons her cousin's Batsuit, altered by Wayne Enterprises employee Luke Fox, before rescuing Sophie and foiling Alice's plan to detonate a bomb in a crowded park. The next day, as the news reports on what they believe is Batman's return, Kate begins to suspect Alice is her fraternal twin sister, Beth, whom she believed was dead.

Kate's growing suspicions about Alice's identity drive a wedge between her and Jacob, who firmly believes Beth is dead based on the evidence. While trying to get Alice's favorite knife tested for DNA, she comes under attack from a group of thugs that manage to steal it back. Deducing one of Alice's injured men used Mary's secret clinic, Kate frees him to give Alice a message. Kate then asks Sophie to buy her time while she meets with Alice, who refuses to directly admit she is Beth, but agrees to provide a DNA sample. Sophie tells Jacob where to find them, resulting in Alice being transported to Arkham Asylum. Alice tells Kate she tasked her boyfriend, ex-Crows agent Dodgson, with killing Mary; prompting Kate to save her before rescuing Alice from a bomb intended to kill her before both Kate and Alice escape from the police. Meanwhile, Kate's stepmother, Catherine, orders the thugs she tasked with stealing Alice's knife to destroy it. After interrogating Dodgson, Kate finds a parcel containing a live bat and a note from Alice that implies she knows her identity.

Bruce's former childhood friend, Thomas Elliot, leaves Kate an invitation to a gala celebrating the purchase of the building overlooking Wayne Tower. Around the same time, a railgun designed to penetrate the Batsuit is stolen from a Wayne Enterprises facility. Kate correctly infers that Elliot is the thief, having learned Bruce's true identity and intends to kill Batman for saving his mother years earlier, delaying his inheritance. When he takes hostages to force Batman out, Kate confronts him in a modified suit, adopting the persona of Batwoman as she rescues the hostages and disables the railgun. Alice subdues Elliot to save a cornered Batwoman, but they part on less than amicable terms while the Crows take Elliot to Arkham Asylum. Elsewhere, Sophie finds herself pondering her relationship with Kate, but dismisses them after entering a relationship with a bartender, Reagan. Catherine finds playing cards left by Alice in her bedroom, demanding Jacob deal with her despite his concerns that she might be Beth. Gotham publicly learns about Batwoman.

Kate's relationship with Reagan complicates her efforts to catch jewel thief Magpie, who has stolen Martha Wayne's necklace, and puts her newfound status as Gotham's protector in question. When Dodgson develops an infection during his captivity, Batwoman drops him off with Mary for treatment. While he is drugged with morphine, Mary impersonates Alice and gets him to reveal part of her plan: a mysterious figure named Mouse. After getting the necklace back, Batwoman foils Magpie's latest heist at a museum gala; allowing the Crows to arrest her and take her to Blackgate Penitentiary. Recognizing that she cannot be in an honest relationship, Kate breaks up with Reagan. To provide a cover for her vigilantism, Kate sets up a company to buy dilapidated buildings and turn them into low-cost housing with Luke as her assistant. Meanwhile, Alice meets with Catherine at Beth's grave and demands she turn over an experimental weapon; threatening to tell Jacob the truth about Beth. Catherine confesses to Jacob that she used a deer skull in place of Beth's, causing him to storm out.

Alice is linked to a series of skin thefts in Gotham, so Kate captures her and gives her the chance to explain herself, while also leaving Jacob and Sophie a trail to follow. The sisters travel to the rural area where Beth was last seen. A series of flashbacks show Beth being rescued from drowning and subsequently being held captive by a man who wants her to be a companion for his disfigured son, Jonathan Cartwright, who will later become Mouse. Catherine tells Mary the truth about her deception and she storms into Wayne Enterprises in a drunken stupor. Luke calms her by letting her assist with his skin theft investigation, learning that they are connected to several escaped Arkham prisoners. Alice drugs Kate and locks her in Mouse's home. When Jacob and Sophie show up after subduing Dodgson and the Wonderland Gang members with him, Alice stabs her father. Kate escapes, takes Mouse captive with Sophie's help, and forces him and Alice to leave. Jacob recovers, but now fully accepts that Alice is Beth. Alice promises Mouse, who she calls her "brother", that she will help him become whoever he wants to be.

A vigilante calling himself the "Executioner" begins targeting law enforcement and judicial officials he deems to be corrupt. Alice has Mouse impersonate Catherine's researcher Dean Devereaux to steal the weapon she refused to turn over. However, Alice convinces him not to as she still needs him for an upcoming tea party. When he discovers that the Coil Accelerator was intended to kill Batwoman, Mouse feels betrayed and confronts Alice; believing she wants to protect her sister while killing Deveraux. Sophie deduces Batwoman's identity, but is injured by the Executioner during his latest attack; forcing Kate to take her to Mary. A flash drive is located, which proves the Executioner's claims to be true. This upsets Luke, as he fears it would allow his father, Lucius', killer to request a re-trial. Sophie escapes, but not before Mary urges her not to reveal Batwoman's identity. Jacob manages to kill the Executioner, only to be caught in one of his traps. After Batwoman saves him, he tells her he was wrong to blame Batman for what happened to Beth and his wife.

Kate runs into her old friend, Julia Pennyworth, while on the trail of a professional assassin called "The Rifle". Sophie threatens to tell Jacob Kate's identity unless she ceases her vigilantism. The Rifle meets with Alice and hands over a mysterious vial as he mentions his boss Safiyah. Kate invites Sophie to a local restaurant, where their show of affection upsets the homophobic owner. When they leave, Sophie confesses that Jacob was the one who convinced her to end their relationship, putting her on the path to where she is now. Catherine goes to see Jacob, who reluctantly agrees to hold off filing for divorce. Julia poses as Batwoman so Kate can trick Sophie, but winds up captured by the Crows when the Rifle ambushes her with the Coil Accelerator. Kate breaks her out and Sophie concludes that she was wrong. Nevertheless, Kate tells her it's best they stop seeing each other. After purchasing a space, Kate and Mary open a gay bar. Jacob meets with Alice, revealing himself as Mouse, while the Rifle leaves for the Mediterranean with Julia in pursuit as the real Jacob returns from upstate. Alice puts the next stage of her plan in action.

Alice has Jacob abducted while Mouse sequesters Sophie and Tyler as her plan unfolds. On Alice's orders, disguised Wonderland Gang members replace the security detail assigned to protect Gotham's Humanitarian Ball, where Catherine is to be awarded. Alice rewrites her speech, making her confess to numerous crimes before collapsing. Alice tells a captured Catherine and Mary they have been poisoned by a toxin developed by the former's company and there is only enough antidote for one. Catherine compels Mary to take it, expressing how proud of her she is before she dies. As Batwoman neutralizes the Wonderland Gang, she nearly strangles Alice in anger upon learning of her actions. However Mouse, disguised as Jacob, stuns Batwoman to exfil Alice. Jacob awakes to find himself framed for Catherine's death and arrested by Commissioner Forbes. Furious that Kate chose to believe in Alice, Mary is left devastated by her mother's death. Tired of doubting, Tyler asks Sophie to decide whether she loves him or Kate. As Kate visits Jacob, both agree Alice is beyond saving and must be stopped. Meanwhile in Central City, Nash Wells uncovers a wall of symbols before a blinding light pulls him inside.

To aid the heroes, Harbinger recruits Earth-74's Mick Rory and his Waverider. After Oliver Queen's death, the Monitor consults the Book of Destiny and learns of seven Paragons. Two are Sara Lance, Paragon of Destiny and Kara Danvers, Paragon of Hope but, to find two more, Clark Kent, Lois Lane, and Iris West-Allen must locate a Superman who has suffered "more than any mortal man" while Kate and Kara search for the "Bat of the Future," complicated by Lex Luthor stealing the Book in order to kill Supermen across the multiverse. When he finds Earth-96's Superman at the same time as Clark's team, he forces the Kryptonians to fight each other until Lois stops him. Meanwhile, Kate and Kara locate Earth-99's Bruce Wayne, an aged killer, but fail to convince him to join them. A heated confrontation erupts wherein Bruce is accidentally electrocuted. Elsewhere, Sara, Barry Allen, Mia Smoak, and John Constantine take Oliver's body to a Lazarus Pit to resurrect him, but it fails. Back on the Waverider, Ray Palmer builds a "Paragon detector," which identifies Kate as the "Bat of the Future." Unbeknownst to everyone, Harbinger is approached by the Anti-Monitor.

This episode continues a crossover event that begins on Supergirl season 5 episode 9, continues on The Flash season 6 episode 9 and Arrow season 8 episode 8, and concludes on Legends of Tomorrow's special episode.

Following Catherine's death and Jacob's arrest, Mary tries to find an expert to testify in Jacob's defense and continues to distance herself from Kate while Sophie takes command of the Crows. After Batwoman saves a hacked train from crashing, the perpetrator demands a large sum of money as ransom or they will release all of Gotham's secrets online. Luke tracks the culprit to Gotham Prep, where Batwoman learns it was a lesbian student named Parker Torres, who was outed to her heteronormative parents by an ex-girlfriend and hoped to leave Gotham with the blackmail money. Alice breaks into the school, abducts Parker, and forces Batwoman to unmask herself to Parker or else she will murder her. She also threatens the school with a bomb and attempts to force Parker to out Batwoman's identity, but Parker contacts the Crows and GCPD instead, who evacuate the building and arrest Alice. Afterwards, Kate offers Parker emotional support and reconciles with Mary. Batwoman later comes out as a lesbian superhero in an interview with Kara. Jacob has encounters with a tough inmate named Reggie Harris. When she returns to Wayne Tower, Kate meets a doppelgänger of Beth, who happily greets her.

In flashbacks, Beth was shown to have an improving friendship with Mouse, but his father August Cartwright did not approve and got her involved in his latest project. In the present, Kate tries to clear things up with the second Beth; who got displaced from her Earth following the Crisis. To free Alice, Mouse kidnaps Commissioner Forbes' and Mayor Akins' sons before he and the Wonderland Gang intercept Kate before she can become Batwoman. Using a code Kate and Sophie learned, Sophie refuses to yield to Mouse's demands. In an attempt to fool Alice, Luke and Mary disguise the second Beth as Alice to buy Kate time to break free. When "Alice" does not use the proper code, Mouse captures her. Kate breaks free, subdues the Wonderland Gang, and injures Mouse before rescuing the hostages. Alice gets out before she can be taken to Arkham, telling Sophie she has her own demons to deal with. With Mouse under heavy guard in the ICU, protestors appear outside GCPD, demanding they light the Bat-Signal as Batwoman arrives. Later, Kate celebrates her birthday with Luke, Mary, and Beth. Suddenly, both Beth and Alice simultaneously suffer from migraines.

Sophie and Jacob petition Dr. Campbell for his testimony, who agrees if he can examine Mouse. Alice visits Mouse and learns of her doppelgänger as she continues to suffer from migraines. When she meets her in Wayne Tower, Beth theorizes that only one of them can be saved. Remembering that Mary's blood has the "cure-all" antidote, Alice attacks her at her clinic to save herself, but Mary leaves Alice handcuffed to a clinic bed and escapes to give her blood to Kate so she can save Beth. Meanwhile, Jacob is attacked by Dodgson, then saved by Reggie, who expects him to repay him before the other prisoners find out. Campbell visits Mouse in the ICU, revealing himself as August. Exfiltrating Mouse posed as a guard, August leaves him bound in an unknown location so he can target Alice. After giving Beth the blood sample, Kate attends to a weakened Alice while Luke gets Beth away from the Crows. Though Sophie follows, ready to kill Beth, she chooses to call for an arrest. August snipes Beth instead, mistaking her for Alice, allowing Alice herself to quickly recover and knock out Kate.

With the truth of Catherine's murder disclosed, Jacob is cleared of all charges and regains control of the Crows. At night, people are targeted by a vampire named Nocturna. When Batwoman finds her latest victim, Nocturna stuns her with ketamine before taking a sample of her blood. Sophie helps Batwoman before the Crows find her; advising her to keep her distance. Mary treats Kate before the latter works with Jacob to draw out Nocturna. After speaking with Kate, Alice replaces the missing Mouse with a mannequin before she is attacked by Nocturna. Using facial recognition, Luke recognizes Nocturna as Natalia Knight, who suffers from porphyria. Kate finds Alice just as Nocturna attacks Mary. Alice donates her blood to save Mary before Kate confronts Nocturna and defeats her with a forensic UV light. Jacob confronts Sophie after viewing footage of her helping Batwoman and implores her to pick a side before suspending her until further notice. Mary remembers finding ketamine in Kate's system, and realizes she is Batwoman while Alice realizes Campbell is actually August. Kate visits Sophie by the Bat-Signal and they share a kiss.

In flashbacks, Duela Dent struggles with making her face look "normal," so she smashes a mirror and uses its shards to cut her face. In the present, Duela targets social media influencers. Still suspended, Sophie's mother visits her. Upon learning of her current relationship issues however, she leaves disappointed. August hooks up Mouse to a fear toxin canister and tells him he killed Alice. While investigating Duela, Batwoman determines her next target, Myrtle, and narrowly saves the girl's mother after Duela attacks her. Following this, Luke discovers Myrtle changed her name to Veronica May and Duela's victims were all connected to Dr. Campbell. Batwoman and Sophie later find Duela just as she is to drop Veronica in acid. While Batwoman rescues the latter, Sophie subdues the former and leaves her for the police. However, Alice gets to Duela first and steals her face so she can kidnap Dr. Campbell and reveal she knows his true identity. Meanwhile, as Luke feared, Reggie's lawyer, Bobby Reeves, visits him to establish his client's re-trial date in light of new evidence. Amidst this, Jacob finds himself questioning the circumstances behind Lucius' death.

In flashbacks, Gabi Kane gave her daughters necklaces that matched her earrings. During her time with August, Beth endured torments from his mother Mabel, her "Queen of Hearts". Taking notice of Mabel's earrings, she traced them to a locked refrigerator containing Gabi's head. In retaliation, Beth turned Mabel's oxygen tank into a makeshift flamethrower. In the present, Batwoman finds a bound August near the Bat-Signal and alerts Jacob, who is unwilling to alert the police after what Forbes did to him. When he asks about the second Beth, Kate claims she was a "skin thief" to hide her true nature while Luke and Mary track down her killer. Meanwhile, Alice finds Mouse and frees him, but he hooks her up to the canister and flees, believing she's his greatest fear. Under the effects of the fear toxin, Alice hallucinates a zombified Mabel tormenting her before she breaks free. Jacob arrives soon after while looking for Mouse and uses adrenaline to save her before arresting her. Incensed by what August did to Beth and her mother, Kate accidentally strangles him, much to Jacob's dismay as he returns with Alice.

As Jacob buries August's body, Alice escapes with his gun. She returns to the Wonderland Gang hideout hoping to find Mouse, only to find her gang murdered and a threatening note from Safiyah. She convinces Kate to help her find Mouse, promising to leave Gotham afterwards. They visit a nurse who treated Mouse, only to find the Crows taking him to Arkham. Following a disagreement and fight, Kate agrees to help Alice break him out. They retrieve Mouse's cell key from Dr. Butler, but when Alice goes to free him, Kate locks her in; revealing she was part of a sting operation with Jacob to capture her. Meanwhile, Jacob instructs Sophie to investigate Lucius' death after hearing of Reggie's re-trial. A sniper nearly kills her, but Julia saves her. Luke and Mary attend Reggie's court hearing, where he is granted his re-trial and released. Luke confronts him, but Reggie claims he was set up before he gets shot. Sophie later informs Jacob that two people connected to Lucius' case have turned up dead before the hitman nearly kills him. He defeats him, but the hitman dies from his injuries before he can be interrogated.

Struggling with having killed August, Kate does not suit up for a week. Meanwhile, a past criminal called the Detonator resurfaces; placing people in bomb vests. Kate confronts George Adler, who confirms his deceased father was the original Detonator. Reeves falls victim next, so he contacts the Crows, who work with the GCPD to evacuate Mary's clinic. After Kate rescues Mary, she reveals she knows Batwoman's identity. When Jacob becomes the Detonator's latest target, Kate realizes that Crows agent Robles is responsible. Batwoman intercepts him and learns he is typing up loose ends concerning Lucius' murder and that the latest bomb is in Wayne Enterprises' underground parking garage. There, Batwoman discovers that Robles was paid by Elliot to get Lucius' journals, leading to his accidental death and Reggie being framed. Luke overhears and Kate stops him from taking vengeance, admitting that she killed August. Luke places the building on lockdown, limiting the blast radius. Jacob reinstates Sophie while Julia is transferred to the Crows. Meanwhile, Alice and Mouse, disguised as Butler, decide to take over Arkham to keep themselves safe from Safiyah.

Batwoman plans to go after Lucius' journal, which is currently being held by Elliot's associate, Johnny Sabatino. With Luke's assistance in the Batcave, Kate and Julia infiltrate Sabatino's club, only to get captured. In response, Luke is forced to ask Mary for help in rescuing them. Meanwhile, Alice agrees to give Elliot a new face in exchange for the journal and to keep the Crows from putting him on trial. As Sabatino refuses to give up the journal however, Alice sends Magpie to retrieve it while she and Mouse work on Elliot's new face. The Crows later visit Arkham and find what appears to be Elliot hanged in his cell. As Julia is being tortured, Sabatino auctions off the chance to kill Batwoman. However, Mary frees Batwoman while Julia frees herself before they defeat the criminals and retrieve Lucius' journal before Magpie. After meeting Reagan at the club, Kate has a one-night stand with her, only to find the journal missing the next morning. Elsewhere, Reagan gives it to Magpie, who in turn gives it to Alice. While pouring over the journal however, she and Mouse discover it has been written in code.

Kate storms Reagan's apartment and learns who she gave the journal to. Taking up the identity of Hush, Elliot abducts members of Gotham's Intelligentsia to decipher the journal on Alice's behalf and kills them when they fail to. He nearly abducts Parker, but Batwoman interferes; forcing him to escape. In response, Alice sends Hush after Luke and Julia. With help from Mary and Parker, Batwoman confronts Alice and offers Lucius' glasses in exchange for their safety. Once she gets what she needs from the journal, Alice releases Arkham's inmates and destroys Mouse's disguise before escaping into the tunnels. Following the incident, Jacob warns Batwoman that a war will start between her and the Crows should she ever resurface. Julia tells Kate that she was after the book for the Rifle's boss, Safiyah Sohail, but called off the deal after learning what it does. In the sewers, Alice continues reading through the journal and orders her associates to procure Kryptonite.

Jacob and Batwoman confront Arkham escapee Tim "The Titan" Teslow, only to be defeated. Mouse shows Alice a mobile app developed for people to send alerts to the Crows. After learning that Kryptonite can pierce the Batsuit, Luke shows Kate a shard of Kryptonite that Bruce had; intent on destroying it before it falls into the wrong hands. Batwoman meets with Tim's brother, Apollo, to warn him, but Tim attacks and kills him. Mary lights the Bat-Signal to get Jacob's attention and convince him to call a truce with Batwoman to stop Tim. Alice kills Mouse when he begins to affect her plans. Batwoman and the Crows lure Tim to Gotham Stadium, but just as she reasons with him, the Crows kill Tim and Jacob reneges on the truce; forcing Batwoman to flee. At the Crows' headquarters, Jacob reaffirms his desire to take down Batwoman while Sophie learns about Safiyah from Julia. Kate shows Luke and Mary the Kryptonite in her possession, entrusted to her by Supergirl. Alice finishes Elliot's new face, making him resemble Bruce Wayne.

Vandal Savage arrives in Central City, seeking to kill Kendra. Barry goes to Star City and enlists the help of Oliver and his team to protect her. The team is visited by Malcolm who informs them that Savage is an immortal. Later, Kendra is kidnapped by Hawkman, but Barry and Oliver rescue her and capture Hawkman, who introducing himself as Carter Hall, tells them he and Kendra are soulmates who have been connected for millennia. The pair are destined to die, be reborn, and find each other in each lifetime. Carter also reveals that Savage has killed the pair several times, each time growing stronger. Savage acquires the Staff of Horus, a deadly weapon. Kendra unlocks her abilities and the team decides to regroup in Central City, where Oliver witnesses Samantha Clayton with her son, who is also his. Meanwhile, Caitlin and Harry create a serum that will temporarily increase Barry's speed so that he can defeat Zoom. Jay initially refuses to test the serum, but changes his mind to save Harry when the latter is shot by an unaware Patty, whom Joe later informs about the truth. However, Jay advises against using the serum on Barry.

Malcolm orchestrates a meeting between Vandal Savage, Barry Allen, and Oliver. Savage demands they turn over Kendra Saunders and Carter Hall or he will destroy both Central City and Star City with the Staff of Horus. They devise a plan to deliver the pair as a ruse to get close enough to destroy the staff. The plan fails; Kendra and Carter are killed and Savage uses the staff to destroy everyone else in the city. Barry escapes and runs fast enough to go back in time to the point of the original negotiation. Barry informs Oliver of his time travel and the mistakes that led to their defeat. They change their approach to the plan and Barry is able to steal the staff. He and Oliver use it on Savage, burning his body. Afterward, Kendra and Carter decide to use their powers to help others in another city. Cisco gives her a tracking device. Meanwhile, Oliver learns about his son, William, and accepts Samantha Clayton's, William's mother, condition not to tell William or anyone else about the paternity in order to be able to see William. Malcolm collects Savage's ashes while whispering, "You owe me one, buddy.".

Barry investigates a meteor crash outside Central City that turns out to be a spaceship from which aliens emerge. Lyla tells the team that the "Dominators" landed previously in the 1950s, but then mysteriously departed. Needing help, Barry assembles the original Team Arrow, Thea, the Legends, and Supergirl of Earth-38. The team begins training at a S.T.A.R. Labs facility, sparring against Supergirl to prepare against the aliens. Cisco finds and reveals a message to Rip Hunter from Barry's future self, which exposes Barry's manipulation of the timeline and how it affected other team members. Oliver, Supergirl, Felicity, Martin and Jefferson become the only ones who still trust Barry. The Dominators abduct the President. Supergirl leads most of the others in a rescue effort, but the Dominators kill the President and trap them with a mind control device. The controlled heroes return and attack S.T.A.R. Labs. While Oliver holds them off, Barry lures Supergirl to the device and manipulates her into destroying it, freeing everyone. The team decides to trust Barry again. Suddenly, Sara, Ray, Diggle, Thea, and Oliver are teleported away before Barry can intervene.

Oliver finds himself back at Queen Manor; both his parents are alive, he is about to be married to Laurel Lance, and Diggle is the Hood. However, it is revealed that he, Diggle, Thea, Sara and Ray are all being held unconscious inside pods aboard a Dominator spaceship. Meanwhile, Felicity, Curtis and Cisco Ramon try to hack into the Dominators' mainframe using a piece of their technology. The team recovers a necessary device with the help of the Flash and Supergirl, and they manage to locate the others. Oliver begins seeing flashes of his former life, as do Sara and Ray. All five captives soon realize that they are inside a shared hallucination. Their escape attempt is blocked by manifestations of Malcolm Merlyn, Deathstroke, Damien Darhk and their mercenaries, all of whom are defeated by the captives. The captives then leave the dream and awaken inside the ship. Escaping in a shuttle, they are rescued by the Waverider. Ray deduces that the Dominators were gathering information from their minds, using the hallucination as a distraction, to help them complete a special "weapon". The team learns that the Dominator mothership is headed toward Earth.

Nate, Mick, Amaya, Felicity and Cisco travel back to the first Dominator invasion of Earth in Oregon, 1951. The Legends successfully capture a Dominator for information, but are themselves captured by federal agents. While in custody, they learn from the Dominator that the aliens arrived to assess the threat humanity posed now that metahumans have appeared. Felicity and Cisco rescue the Legends and help set the Dominator free. Meanwhile in Central City 2016, the team learns that the Dominators know about Barry's manipulation of the timeline, and that they demand his surrender in exchange for peace. After the Legends return, the team discovers that the Dominators' weapon is a bomb that will kill all metahumans on Earth, with millions of collateral human casualties. The teams dissuade Barry from surrendering, with Cisco reconciling with him. They manage to destroy the bomb and force the Dominators to retreat using pain-inflicting nanotechnology. Cisco gives Supergirl a device to travel between their universes. Martin convinces Jefferson not to tell the others that his daughter, Lily, is an aberration of the timeline.

On a parallel world, Earth-X (Earth-53), a Nazi regime rules the planet where an archer, Dark Arrow, is the Fuhrer, and personally hunts the resistance forces. Dark Arrow seizes a temporal gateway from the Freedom Fighters members including James' parallel universe doppelgänger, a device that allows interdimensional travel to other universes; he schemes to invade parallel Earths with the device to spread his reign so that it may last. Kara and Alex travel to Earth-1 to attend Barry Allen's wedding with Iris West. Alex meets the Legends' leader Sara Lance / White Canary, taking the first step to recover from her break up with Maggie. The wedding ceremony is interrupted by Earth-X Nazi invaders, led by Dark Arrow, his Kryptonian-powered wife Overgirl, and his partner Prometheus. After Kara defeats and injures Overgirl during the fight the Nazis retreat, and Alex and Sara capture Prometheus to interrogate. As Overgirl recuperates, she, Dark Arrow, and a yellow-clad speedster regroup and discuss their next move, Dark Arrow and Overgirl are revealed as parallel universe doppelgängers of Oliver Queen / Green Arrow and Kara, and the yellow speedster is Barry's nemesis from the 22nd century Eobard Thawne / Reverse-Flash.

In S.T.A.R. Labs, a captured interdimensional villain from Earth-X, Prometheus-X, is revealed to be a parallel universe doppelgänger of Tommy Merlyn. After he cruelly taunts Oliver over his attachment to Earth-1's Tommy, Prometheus-X commits suicide out of loyalty to Earth-X's Nazi regime. Prometheus-X's partners, Dark Arrow (Oliver's doppelgänger), Overgirl (Kara Danvers' doppelgänger), and Eobard Thawne steal a sublight generator, the Prism, from research company Dayton Optical Systems; Oliver, Barry, Kara, and the others believe that Dark Arrow seeks to build a neutron bomb with it to aid in his conquest of Earth-1. After a series of battles, most of the heroes - including Team Arrow - are held captive at S.T.A.R. Labs after Nazi forces infiltrate it. Oliver, Barry, and his allies are abducted to Earth-X's concentration camp, but Kara is moved to S.T.A.R. Labs. Oliver is determined to kill Dark Arrow after his capture. The villains reveal that Overgirl is dying and Dark Arrow plans to use the Prism, charged by S.T.A.R. Labs' particle accelerator, to produce artificial red sunlight and remove Kara and Overgirl's invulnerability, allowing a heart transplant for Overgirl but killing Kara in the process.

Barry, Oliver, Sara, Alex, Martin and Jax wake up in a Nazi concentration camp on Earth-X wearing power dampeners. The arriving SS Sturmbannfuhrer is revealed to be the Earth-X doppelgänger of Quentin Lance, who plans to execute them, but they are saved by Citizen Cold (the Earth-X doppelgänger of Leonard Snart) and Ray Terrill. Snart and Terrill take them to the headquarters of the Freedom Fighters, where the team meets the resistance movement's leader, General Schott (Winn Schott's Earth-X doppelgänger). They learn that the only way back to Earth-1 is through a temporal gateway in a research facility, which Schott plans to blow up to strand Dark Arrow (Oliver's Earth-X doppelgänger) on Earth-1. Oliver disguises himself as Dark Arrow to infiltrate the facility and discovers the Nazis have a contingency plan, a militarized timeship called Wellenreiter. Barry and Ray battle the Freedom Fighters' Red Tornado to stop it from destroying the gateway while the rest of the team enter the facility to reactivate its portal. During the battle, Stein is shot and gravely wounded. On Earth-1, Eobard Thawne prepares to perform surgery on Kara to save Overgirl. Felicity and Iris try to stop him, but are captured.

On Earth-X, Stein activates the temporal gateway's portal before succumbing to his injuries. Jax bonds with Stein to get him through the portal, along with Barry, Oliver, Sara, Alex, Ray Terrill, and Leo Snart (Leonard Snart's Earth-X doppelgänger). Members of all the teams face off against Earth-X Metallo, while Felicity and Kara are cornered by Dark Arrow before Oliver saves them. Jax is also affected by Stein's wounds; Stein severs their link and dies. Dark Arrow attempts to negotiate for Kara, but Oliver refuses and the team battles Dark Arrow's forces. Caitlin, Amaya, and Zari infiltrate the Nazis' timeship Wellenreiter to disable its shields so that Harry and Cisco can destroy it with the Waverider. Barry defeats Thawne, but allows him to escape, resuming their feud. Supergirl battles Overgirl, flying her into space to detonate away from the Earth when she goes nuclear. Oliver fights and kills Dark Arrow. Terrill returns to Earth-X, but Snart chooses to stay for the meantime and joins the Legends. The team holds a funeral for Stein. The Legends, Kara, and Alex depart back to their own lives. Barry and Iris are officially married by John Diggle, who also marries Oliver and Felicity.

On a decimated Earth-90, the Flash is seen crawling towards a book, but a mysterious stranger picks it up and uses it to destroy that reality; though the Flash escapes. On Earth-1, the stranger presents the book to Arkham Asylum psychiatrist Dr. John Deegan, and instructs him to rewrite reality as he sees fit. The following morning, under threatening red skies, Oliver Queen and Barry discover that they have swapped lives, with everyone believing they are each other. When they seek the assistance of Team Flash, they do not believe them and lock Barry and Oliver in the pipeline. Barry and Oliver use each other's abilities to escape and convince a reluctant Iris to allow them to flee to Earth-38 to enlist the help of Kara Danvers / Supergirl and her cousin, Clark Kent / Superman. Back on Earth-1, the heroes join forces to stop AMAZO, an android that can copy their abilities. They stop the android and, after seeing a vision of the stranger from Cisco, they realize they must travel to Gotham City.

Oliver, Barry Allen, and Kara Danvers head to Gotham City to find John Deegan, but are quickly arrested. However, they are bailed out by Kate Kane, who tells them Deegan can be found at Arkham Asylum. With some assistance from Oliver and Barry's teams, they break in to confront Deegan and retrieve the book he used to rewrite reality; only for the doctor to escape and cause a mass breakout. While trying to contain it, Batwoman shows up to help them before telling them to leave Gotham. Returning to A.R.G.U.S., the heroes attempt to unlock the book when the Flash of Earth-90 breaches through to them and warns them of the Monitor. Oliver, Barry, Kara, and Earth-90's Flash go to confront Monitor, but the omnipotent being escapes and returns the book to Deegan; who changes reality once more. This time, Oliver and Barry wake up as wanted criminals and are forced to contend with both police and a black-suited Superman.

Barry Allen and Oliver Queen wake up as wanted criminals hunted by John Deegan as a black suited Superman while Kara is imprisoned at S.T.A.R. Labs, with a rewritten Alex guarding her. After narrowly escaping Deegan, Barry and Oliver locate Cisco Ramon, who works as a mob boss with James as a henchman, and retrieve Superman from Earth-38. Supergirl convinces Alex to release her, and together with Barry retrieves the Book of Destiny. Superman uses the book to return Barry and Oliver to their original forms, but Deegan steals it back. Barry and Kara travel in opposite directions to slow the Earth's rotation in order to impede Deegan, despite Clark saying it will kill them. With help from Lois, Brainy, and J'onn, Superman and Oliver successfully defeat Deegan and restore Earth-1 to normal. On Earth-38, Clark reveals Lois is pregnant, and they are going to be moving to Argo City for a while, leaving Earth in Kara's hands. Clark proposes to Lois and she accepts. On Earth-1, Oliver gets a call from Batwoman, revealing Deegan is in Arkham and has seemingly made friends with the Psycho-Pirate.

As the Crisis begins, Brainy detects an anti-matter wave approaching Argo City, so Kara warns her mother Alura Zor-El, her cousin Clark Kent, and his wife Lois Lane. The Kents narrowly send their son Jonathan off-world just as the wave hits Argo. Meanwhile on Earth-1, Harbinger brings Barry Allen, Kate Kane, Oliver Queen, Mia Smoak, Sara Lance, and Ray Palmer to Earth-38 and rescues the Kents. As Harbinger briefs the heroes on the Anti-Monitor, the Monitor raises a quantum tower to impede the anti-matter wave while the DEO and Lena work to evacuate Earth-38. After learning Jonathan ended up on Earth-16, Lois, Sara and Brainy leave to get him. In preparation, Oliver passes the mantle of Green Arrow to Mia, but when he learns Barry is fated to die, he argues with the Monitor over the deal they made last year.[a] The heroes fend off an army of shadow demons until the Monitor breaches them off-world. However, Oliver stays behind; sacrificing himself to ensure the exodus succeeds. On Earth-1, Lois' team returns with Jonathan before the Monitor brings a dying Oliver to share his good-byes. Nash Wells, now a "pariah" for releasing the Anti-Monitor, appears, announcing everything is doomed.

To aid the heroes, Harbinger recruits Earth-74's Mick Rory and his Waverider. After Oliver Queen's death, the Monitor consults the Book of Destiny and learns of seven Paragons. Two are Sara Lance and Kara Danvers, but to find two more, Clark Kent, Lois Lane, and Iris West-Allen must locate a Superman who has suffered "more than any mortal man" while Kate and Kara search for the "Bat of the Future". Complicated by Lex Luthor stealing the Book in order to kill Supermen across the multiverse. When he finds Earth-96's Superman at the same time as Clark's team, he forces the Kryptonians to fight each other until Lois stops him. Meanwhile, Kate and Kara locate Earth-99's Bruce Wayne, an aged killer, but fail to convince him to join them. A heated confrontation erupts wherein Bruce is accidentally electrocuted. Elsewhere, Sara, Barry Allen, Mia Smoak, and John Constantine take Oliver's body to a Lazarus Pit to resurrect him; but it fails to work. Back on the Waverider, Ray Palmer builds a "Paragon detector", which identifies Kate as the "Bat of the Future". Unbeknownst to everyone, Harbinger is approached by the Anti-Monitor.

Ray Palmer's "Paragon detector" identifies Barry, J'onn J'onzz, and Ivy Town scientist Ryan Choi as the remaining three, so Ralph, Iris, and Ray leave to recruit Choi. After the Monitor restores Cisco's powers, Team Flash and Nash (now Pariah) return to the chamber the latter found; where they find an anti-matter cannon and Earth-90's Flash powering it. Cisco successfully frees him, but the cannon starts going critical, so Pariah recruits Black Lightning from another Earth to help contain the energy. As Barry prepares to destroy the cannon, Earth-90 Barry stops him so he can sacrifice himself in his place. Elsewhere, John Constantine, Mia Smoak, and John Diggle visit Lucifer on Earth-666 to get Oliver Queen's soul back, which they find in Purgatory. Before they can leave, Jim Corrigan appears so he can pass the Spectre's power onto Oliver. He accepts and Constantine's team is sent back without him. While the heroes regroup, the Anti-Monitor sends a brainwashed Harbinger to attack them and kill the Monitor so he can finish destroying the multiverse. Before he's killed, Pariah teleports the Paragons to the Vanishing Point; where they learn Lex Luthor used the Book of Destiny to replace Earth-96's Superman with himself.

In a flashback to the planet Maltus 10,000 years ago, Mar Novu experiments with time travel to see the dawn of time, only to accidentally end up in the anti-matter universe and unleash the Anti-Monitor. Following the multiverse's destruction, the Paragons attempt to find a way out of the Vanishing Point and save the multiverse. With Jim Corrigan's help, Oliver learns how to use the Spectre's power so he can rescue the Paragons and strengthen Barry Allen's powers. With his increased speed, Barry drops off Kara Danvers, Ryan Choi, and Lex Luthor on Maltus to stop Novu, but gets attacked by the Anti-Monitor and loses the others across the Speed Force. Though Kara's team successfully stop Novu and Barry retrieves everyone, upon reaching the dawn of time they learn the Anti-Monitor was released regardless. With Oliver's help, the Paragons engage the god-like being and his shadow demons, holding him off long enough for Oliver to combine the Spectre's power with the Book of Destiny to reboot the multiverse. Despite succeeding, Oliver dies a second and final time in Barry and Sara's arms.

Waking up in the newly recreated universe, the Paragons discover they are the only ones who remember the Crisis and that Earth-38 and Jefferson Pierce's Earth were merged with Earth-1 into a composite universe, later designated as Earth-Prime. Not only that, Oliver Queen's second sacrifice gave them all fresh starts. While J'onn J'onzz uses his psionic powers to bring their allies up to speed, Sara Lance attempts to find Oliver without success. Later that night, the Paragons are attacked by shadow demons. A restored and remorseful Nash Wells discovers that the Anti-Monitor is still alive and plotting to renew his destruction of the multiverse. To stop him once and for all, Nash, Ray Palmer, Barry Allen, and Ryan Choi work to develop a bomb to shrink the Anti-Monitor for eternity while the other heroes distract him. Once it is finished, Kara Danvers uses it on the Anti-Monitor and sends him to the microverse. Sometime later, Barry, Kara, Sara, J'onn, Jefferson, Kate Kane, and Clark Kent hold a memorial service for Oliver before agreeing to work together to protect their new world in his memory.

In the year 2166, Vandal Savage has successfully conquered the entire planet. In an effort to save humanity, time-traveler Rip Hunter travels back to the year 2016 to organize a group of superheroes and supervillains to team-up and stop Savage: Ray Palmer, Sara Lance, Jefferson Jackson and Dr. Martin Stein, Mick Rory, Leonard Snart, Carter Hall, and Kendra Saunders. With everyone assembled, Rip takes the team to 1975 to talk to Professor Boardman, a leading expert on Vandal Savage, to get assistance in locating Savage. While providing information on Vandal, Boardman also reveals that he is the son of Kendra and Carter from one of their past lives. Meanwhile, a time-traveling bounty hunter named Chronos attacks Rip's ship; the team is able to regroup and escape, but not before Professor Boardman is wounded and dies. The attack forces Rip to reveal that Chronos is after him for stealing the time-machine against the wishes of the Time Council, and that part of his quest is based on revenge for Vandal murdering his wife and child in his time.

Still in 1975, the team infiltrate a warhead auction for terrorists under the belief that Savage will be there. Savage becomes aware of their presence and orders them killed. A fight breaks out between the team and the terrorists. They all escape, but not before a piece of Ray's suit is left behind. Angry at the recklessness, Rip points out what happens and how the technology of Ray's suit will create super weapons that lead to the destruction of Central City in 2016. The team splits up, with Professor Stein, Jackson, and Sara retrieving the missing piece of Ray's suit, while Ray, Snart, and Rory go in search of the dagger that kills Kendra and Carter in their first life. The dagger turns out to be in the home of Savage, who imprisons the men and forces them to call the rest of the team. Kendra and Carter go after Savage, while the rest take on Savage's men. During the fight, Savage kills Carter with the dagger, revealing that only Kendra can wield it to kill him. Kendra is injured and the team is forced to retreat and plan a new strategy.

Sara convinces Rip that another way to stop Vandal Savage would be to take away his resources. Rip locates the bank where Savage keeps his money, and he and Sara go there to steal the funds. They realize that Savage's men are guarding the bank, so they take one captive to obtain information on Savage. They learn that Savage is using Carter's blood to give his own men longer lives. Rip and his team engage Savage and reclaim Carter's body, but Rip inadvertently gives Savage the information he will eventually use to kill Rip's wife and son. Meanwhile, Kendra's condition worsens, requiring Ray to shrink down and enter her bloodstream, to stop the pieces of the dagger that stabbed Kendra from reaching her heart. Snart attempts to change his own family's fate by preventing his father from entering prison, but his efforts ultimately change nothing. Rip charts a course for 1986 to intercept Savage again.

The team arrives in Washington, D.C. in 1986 to find a document that will lead them to Savage. The team infiltrates the Pentagon and retrieve a government file that points them toward scientist Valentina Vostok in the Soviet Union. Chronos tracks the team, and Rip is forced to use Russian fighter jets to assist in taking down Chronos. While Ray and Snart go after Vostok, Rip tracks a time anomaly outside of Moscow. Rip finds his mentor Zaman Druce, who offers to pardon Rip and return his new team to their time if Rip voluntarily surrenders. The pardon is a trick, and Zaman attempts to kill Rip. With help from the team, Rip survives and Chronos and Zaman escape. Back on the ship, Rip has Sara and Kendra work together to tame the feral nature that resides in each of them. Dr. Stein infiltrates a research lab and discovers Savage is trying to build an army with the same abilities as Firestorm. Dr. Stein absorbs the energy in Savage's thermal core, but he, Ray, and Mick are captured by the Soviets.

Valentina attempts to trick Dr. Stein into revealing the Firestorm formula, but he refuses. The team brokers a deal with the Bratva to get into the gulag where Ray, Mick, and Stein are being held prisoner. Before they leave, Rip pulls Sara aside and tasks her with killing Stein, should they fail to rescue him, in order to prevent a potential future where an army of Firestorms have destroyed the world. Savage has Ray and Mick tortured in front of Stein to force him to talk. Obtaining the formula, Valentina discovers that Stein is the other half of Firestorm. The team arrives at the gulag just as Valentina enters a reactor to start absorbing energy from a new thermal core. Snart rescues Mick and Ray, but Valentina merges with Stein to create a Soviet Firestorm. Jefferson is able to reach Stein's consciousness and force the two to separate. Without Stein or a quantum splicer, Valentina cannot control the nuclear reaction inside of her and ultimately is destroyed. As the team moves into the time stream, they are attacked by Chronos, who forces them to crash land in Star City of 2046. Here, they are confronted by a green-hooded archer.

The green-hooded archer turns out not to be Oliver Queen, who attacks the team. They retreat back to the Waverider to make repairs and leave 2046. Rip, Sara, Snart, and Mick head to Smoak Industries to find an essential part needed to repair the ship. The team come across a fight in the city between a new gang and Green Arrow. Sara follows the vigilante, who turns out to be John Diggle, Jr., under the alias of Connor Hawke. Connor reveals that Oliver is believed to be dead since vanishing 15 years prior when the son of Slade Wilson, Grant Wilson, arrived in Star City with an army and took over. While searching through Green Arrow's old hideout, Sara and Rip find Oliver, still alive and missing an arm. Oliver directs them to where they can find what they need, but he refuses to help in the struggle. In a fight with Wilson's men, Connor is taken prisoner. Sara goes to Oliver and convinces him to resume the Green Arrow mantle. Sara and Oliver then stop Wilson from executing Connor. With the rest of Rip's team as backup, Oliver is able to defeat Wilson for good. With the ship repaired, the team re-enters the time stream.

Vandal Savage's trail goes cold, and Rip is unable to track it without an upgrade to Gideon's software. The team receives a distress call from another time ship, the Akeron, so Rip decides to chart a course for the disabled ship to steal their current A.I. software. Rip, Dr. Stein, Jefferson, and Mick board the Akeron. Everyone but Stein are captured by time pirates, who want the Waverider. The pirate captain attempts to board the Waverider, but Rip initiates protocols on the Waverider to protect it. As such, the pirates fire on the Waverider, damaging the hull. Sara and Snart attempt to fix the hull but get locked in the engine room, where the air is slowly leaking out. As Stein rescues the others, Ray flies into space to repair the hull from the outside. Meanwhile, Mick betrays the team and leads the pirates to the Waverider. Rip and the others retake the Akeron, while Sara and Snart stop Mick and the pirates on the Waverider. The Akeron's captain thanks Rip by providing the needed upgrade for Gideon and a tip on Savage's most likely location. Snart promises to take care of Mick so that he does not betray the team again and apparently kills Mick in an unknown place and time. Rip also recalls memories of his wife giving up being a Time Master so they could have a relationship.

Rip and the team arrive at Oregon in 1958 to investigate a series of murders seemingly tied to Savage. Infiltrating a mental institution, Sara discovers that Savage is a doctor there under the name Curtis Knox. Ray and Kendra pose as a married couple to investigate a murder in a small suburban area, but discover that Savage lives there as well. Elsewhere, Jefferson is attacked by humanoid, bird-like creatures created by Savage from a Nth metal meteorite that gave Kendra and Carter their powers. While trying to get a wounded victim to the ship, Jefferson is abducted by the local sheriff and delivered to Savage. The team decides to go after Savage at the hospital, where he has already infected Jefferson with the Nth metal and transformed him into one of the creatures. Kendra confronts Savage, but he almost kills her before Ray rescues her. The rest of the team manage to capture Jefferson. Back at the ship, Dr. Stein and Gideon create a serum that cures Jefferson and the other victims. Chronos then arrives and storms the ship, which forces the Waverider to quickly leave, stranding Ray, Sara and Kendra in 1958.

Chronos disables the Waverider and flees back into the timestream, taking Snart with him. Rip is forced to reset Gideon to undo Chronos' sabotage, leaving the ship temporarily stranded in the timestream. Meanwhile, two years pass for Ray, Sara, and Kendra. Ray and Kendra build a life together, while Sara rejoins (from her perspective) the League of Assassins. Rip and the rest of the team arrive in 1960 and get Ray and Kendra. They travel to Nanda Parbat to rescue Sara, but she has fully committed to Ra's al Ghul's mission and turns the team over to him as trespassers to be executed. Rip invokes the trial-by-combat ritual to save the team, with Kendra and Sara named as the champions to fight. Elsewhere, Chronos reveals himself to Snart as Mick Rory, having been found by the Time Masters and trained to be their bounty hunter. Kendra is able to get through to Sara just as Chronos arrives. Ra's frees the team, who successfully stop Chronos and discover his real identity. Imprisoning him on the Waverider, the team decides to try to reform Mick.

The team travels to 2147 to find Savage. They discover he is personally grooming a young child, Per Degaton, who will grow up to unleash a virus that decimates most of the planet and allow Savage to rule the world. After debating on whether to kill Per before he commits this act, the team decides to remove him from the timeline and prevent Savage's rise to power. The kidnapping does not affect the timeline, so Rip releases Per and implores him not to let Savage influence his decisions. Unfortunately, the team's intervention with Per only accelerates the timeline, causing the event to take place sooner. Meanwhile, Ray finds his suit's technology has been used to create autonomous policing robots that Savage will use to help conquer the world, and that his family line founded the company that created them. After settling his differences with Snart for the moment, Mick reveals that the Time Masters have released a group called the "Hunters", whose sole purpose will be to track down the team and kill each of them, including Mick for failing to apprehend Rip and the others.

The team travels to Salvation, Dakota in 1871 to hideout from the Hunters. While Rip decides the next move, the rest of the team goes into town. After getting into a bar fight, the team meets Jonah Hex, who knows they are time travelers and who once fought alongside Rip in years past. Kendra gets flashbacks of one of her previous lives and goes to investigate it, while Ray and the rest of the team head back to town to defend it against the Stillwater gang. Kendra and Sara follow her visions to an old woman, who turns out to be the Kendra from that time period. The woman tells Kendra about losing her own Carter/Hannibal Hawkes and warns her not to love a different man, as it will always end in tragedy. The team goes after the Stillwater gang and captures their leader Jeb, but Jackson is apprehended as they escape. The team sets up a quick draw duel between Rip and Jeb to barter for Jackson's life. Rip wins, but the Hunters arrive before the team can leave. They defeat the Hunters, but not before they learn the Time Masters have sent the "Pilgrim" to erase each of them from the timeline by killing their younger selves.

The Pilgrim begins targeting each of the team members. Gideon uses the Pilgrim's temporal distortions to predict her next move. After they successfully rescue Mick and Sara's younger selves, Gideon loses track of the Pilgrim's movement allowing her to take out any of the team without them knowing. The Pilgrim goes after Ray, but the team arrives just in time to save his former self and prevent Ray's death. Rip decides to abduct the rest of the team's infant selves to prevent the Pilgrim from killing any version of them. They are successful, bringing the infants to Rip's adoptive mother to look after until they can stop the Pilgrim. The Pilgrim kidnaps Jefferson's father, threatening to kill him and everyone else's loved ones, unless they give themselves up to her. Rip agrees to give his younger self, before he became a Time Master, in exchange for everyone's life. The Pilgrim agrees, but the team set a trap for her. The Pilgrim is able to freeze the team as they attack, but fails to notice Rip's younger self as he stabs her. Distracted, the team is able to destroy the Pilgrim. Meanwhile, Ray and Kendra become engaged.

The team travels to London in 2166, to try to eliminate Savage just before he finally takes over the world. While investigating Savage, Kendra notices that one of his female officers is wearing a bracelet that she originally wore when she first died in ancient Egypt. The team plans to retrieve the bracelet, hoping that it will help them kill Savage. They also join forces with local rebels. The officer turns out to be Savage's daughter. Snart kidnaps her when he realizes she knows about the team, and he manages to convince her to assist them by showing her Savage's true nature. Rory helps Kendra melt the bracelet down and coat Carter's mace so that it can be used to kill Savage. Ray discovers that Savage's ultimate weapon is a giant robot, which then severely damages the Waverider. While the others go after Savage, Ray reverses the polarity of his suit so that he can grow in size and takes out the robot. The mace works, but Kendra refuses to kill Savage when she learns that he has brainwashed that generation's incarnation of Carter to be his soldier. To save Carter's mind, she and Rip imprison Savage on the Waverider.

Upon the revelation that the giant robot was technology from the distant future, showing Savage is manipulating time, Rip believes the Time Masters will finally sanction his mision and sets course for the Vanishing Point. Jefferson fixes the damaged time drive, but is exposed to time radiation which is slowly killing him. Stein is forced to send him back to 2016 in the jump ship to reverse the process. Carter is kept prisoner while Kendra tries to restore his memories, causing a rift between her and Ray which effectively ends their relationship. Savage tries to manipulate each of the team members, which allows him to escape his cell. Just as Savage is about to kill Kendra, Carter regains his memories and saves her, but is stabbed by Savage before Kendra knocks out the villain. The team arrives at the Vanishing Point, where the Time Masters reveal that Savage has been working with the Time Masters and is to be sent back to 2166 to carry on with his plan, while Rip and his team are put under arrest.

Mick is taken to be reconditioned back into Chronos, while Kendra and Carter are turned over to Savage as he returns to 2166. Sara and Snart, who evaded capture, make plans to rescue the team with the help of Gideon. Zaman explains to Rip that the Time Masters helped Savage because an alien race will attack Earth in 2175, and only Savage is able to unite the world and stop them. Zaman also reveals the Oculus, which the Time Masters used to manipulate Rip and his team to help facilitate Savage's rise to power, including the murder of Rip's family. Snart and Sara disable the other time ships and rescue the others. In order to reclaim their destinies, the team decides to destroy the Oculus. However, when they arrive, Zaman is there with soldiers, having expected them. Jefferson returns in the jump ship, his affliction cured, and takes out the soldiers. Snart sacrifices himself to ensure the Oculus' destruction. Mourning the loss of their comrade, the team plans to go after Savage.

Rip returns the team to 2016, unwilling to let them continue with his mission, but they insist on seeing it through. Kendra leaves a message for the team alerting them to Savage's presence in 1944 France, but they are unable to stop him and can rescue only Carter. Savage reveals that the Thanagarians sent three meteors to ancient Egypt. He plans to use Kendra's and Carter's blood to activate the meteors' alien technology and erase time back to 1700 BC, where he will rule. Dr. Stein deduces Savage's method: to conduct the same ritual across three separate time periods, creating a paradox that will facilitate time's destruction. He also concludes that radiation from all three meteors will render Savage mortal, so anyone can kill him. The team breaks up into pairs - Mick and Ray, Sara and Firestorm, and Rip and Carter - and travel to 1958, 1975, and 2021, respectively. All three groups kill Savage. Ray and Firestorm destroy their meteors, and Rip uses the Waverider to send the last meteor into the sun before it explodes and destroys the Earth. Kendra and Carter stay behind in 2016 while the others decide to help Rip protect the timeline. Before they leave 2016, however, Rex Tyler arrives and warns the team of their impending death.

In 2016, historian Nate Heywood enlists Mayor Oliver Queen's help in locating the Waverider after it was caught in a nuclear blast in 1942. The pair find the sunken ship with only Mick aboard in stasis, who tells them what happened after being revived. Rip's team - Mick, Ray, Sara, Jax, and Martin - traveled through time dealing with "aberrations" in history. They learned that a nuclear bomb would be detonated in New York City in 1942. The team discovered Damien Darhk, working with the Nazis, was behind the attack. Sara attempted to kill Darhk to prevent Laurel's death, but Darhk escaped and launched his sole atomic bomb toward New York from a U-boat. Rip chose to scatter the team throughout time, except for the injured Mick, to save their lives while he intercepted the bomb with the Waverider and saved New York. In the present, Mick and Nate use the Waverider to travel through time and rescue everyone, but fail to find any trace of Rip. After fixing events in 1942 to prevent the Nazis from making a nuclear bomb, the team is confronted by the Justice Society of America (JSA). Meanwhile, Darhk is shown to be working with Eobard Thawne.

The Justice Society captures the team, believing them to be Nazi spies. Nate reveals that he is the grandson of JSA member Commander Steel. After the JSA is assigned a mission to obtain information on Nazi Captain Baron Krieger, they release the team and strongly advises them to leave 1942. The JSA learns that Krieger was given a serum by Eobard, who wants to make a deal for an amulet in Hitler's possession. Nate soon discovers that the JSA dies on this mission, so the team travels back to rescue them. While the others collect the amulet and fight the Nazis, Krieger uses the serum on himself and turns into a monstrous superhuman. He manages to capture Ray and JSA member Amaya. Ray offers to replicate the formula to save Amaya. The teams then attack the Nazi base, save Ray and Amaya, and take down Krieger. However, hemophiliac Nate is critically injured in the process. Ray saves him by using the modified serum he developed. After the team departs, Eobard appears at the JSA headquarters and stabs Rex Tyler to erase him from the timeline before stealing the amulet. A dying Rex whispers "time traveler" to Amaya.

Amaya stows away on the Waverider and attacks Mick, believing him responsible for Rex's death. Nate stops her using his newly-developed metahuman ability to convert his body to a steel-like form. Sara convinces Amaya that a rogue time traveller is likey to blame for the murder. An accident during Ray's testing of Nate's abilities throws both men into the time vortex and strands them in 17th century feudal Japan. Nate is found and cared for by Masako Yamashiro, the betrothed of shogun Tokugawa Iemitsu, whose samurai capture Ray. Sara, Amaya and Mick rescue Ray from Tokugawa, who uses the Atom suit against them. They meet up with a recovered Nate, who does not want to leave Masako to Tokugawa's mercy. They defend Masako's village from the samurai, while Ray and Nate defeat Tokugawa by destroying the Atom suit. Nate and Amaya officially join the team. Meanwhile, Jefferson and Stein discover a hidden armory inside the ship and a secret message from Barry Allen from 2056 intended for Rip and forbidden for the crew.

The team learns of a time pirate stranded in the American Civil War. Upon arriving, they encounter a black man, Henry Scott, being chased by Confederate soldiers turned into zombies from a virus carried by the pirate. The team defeats the group of zombies, but Henry is killed. Before his death, Henry reveals he is a Union spy assigned to steal Confederate battle plans for General Grant, and asks Jefferson to complete his mission. The team discovers that Mick is infected with the virus and return him to the Waverider, where Ray and Martin ultimately manage to cure him. Sara and Nate go to warn Grant about the zombies, while Jax and Amaya attempt to steal the plans. Jefferson runs afoul of a plantation owner and is locked up. Amaya frees him, along with other black prisoners. They find the plans and burn down the mansion during a zombie attack. Meanwhile, Grant's camp is also attacked by zombies. Sara formulates a successful plan to kill them using Nate's powers. Jax, as Henry Scott, gives the plans to Grant, which will ensure a Union battle victory. A grateful Mick gives Leonard Snart's cold gun to Ray.

In 1987, Eobard Thawne offers Damien Darhk an alliance, which Darhk declines. Aboard the Waverider, Nate discovers an aberration in 1987 involving the INF treaty signing. The team infiltrates the White House as tourists and find Darhk there as one of the treaty negotiators. Sara again attempts to kill him, which alerts White House security and forces the team to make a very public escape. They soon learn that Darhk is making his own secret deal with the KGB. Returning to the White House during a State dinner, they discover him making an exchange with KGB agents for a box with an unknown item. The team defeat Darhk's men and the Russians. Sara confronts Darhk, but spares his life. Instead, she reveals his future to torture him: his master plan's failure, his wife's murder, and his own eventual death. Eobard whisks Darhk away, but not before Sara steals the box from him. She realizes the team is up against a time-travelling speedster. Unnerved by Sara's revelation, Darhk insists on teaming up with Eobard, and the two enter the time stream.

The team learns of an aberration in Colorado, 1874, where they save Jonah Hex from execution. He reveals that he is fighting an outlaw boss named Quentin Turnbull. Nate reveals that the aberration is Turnbull leading the Western US in its secession to form the "Turnbull Country". The team learns that Turnbull is extracting dwarf star, which Ray used for his A.T.O.M. suit, and that Turnbull is planning to destroy a critical railway connecting the Eastern US to the West, stopping the US Army from marching toward the West. While Sara and Jonah engage Turnbull, Mick and Amaya destroy the mine, and Nate uses his powers to stop the train. Instead of killing Turnbull, Jonah decides to deliver him to the authorities. With the dwarf star taken, Ray plans to rebuild his suit, and shows Nate the suit he has made for the latter. Amaya decides to teach Mick to control his anger. Martin and Jefferson deduce that due to the former's interaction with his past self, he may have married another woman. Sara tells the team that they need to return to 2016 to help their friends.

Nate, Mick, Amaya, Felicity and Cisco travel back to the first Dominator invasion of Earth in Oregon, 1951. The Legends successfully capture a Dominator for information, but are themselves captured by federal agents. While in custody, they learn from the Dominator that the aliens arrived to assess the threat humanity posed now that metahumans have appeared. Felicity and Cisco rescue the Legends and help set the Dominator free. Meanwhile in Central City 2016, the team learns that the Dominators know about Barry's manipulation of the timeline, and that they demand his surrender in exchange for peace. After the Legends return, the team discovers that the Dominators' weapon is a bomb that will kill all metahumans on Earth, with millions of collateral human casualties. The teams dissuade Barry from surrendering, with Cisco reconciling with him. They manage to destroy the bomb and force the Dominators to retreat using pain-inflicting nanotechnology. Cisco gives Supergirl a device to travel between their universes. Martin convinces Jefferson not to tell the others that his daughter, Lily, is an aberration of the timeline.

This episode concludes a crossover that began on The Flash season 3 episode 8 and continued on Arrow season 5 episode 8.

Eobard, Darhk and Malcolm Merlyn arrive in Chicago, 1927, and ally with Al Capone. Learning of the aberration, the Legends arrive and manage to keep Capone from murdering Eliot Ness. Ness is critically injured, so the team decides to obtain vital information on Capone's operation to secure history. Meanwhile, Mick begins having hallucinations of Snart, who belittles him for acting like his teammates. Sara and Martin are abducted by Eobard during their infiltration and raid on Capone's club. Malcolm offers Sara a chance to change her past in return for the amulet she took from Darhk in 1987, but she refuses. The team rescues the captives, but "Martin" turns out to be a disguised Eobard, who searches the Waverider at super-speed for the amulet while Malcolm attacks the ship directly. Eobard barely escapes revenge at Amaya's hand, but Sara surrenders the amulet for Martin's safety. The Legends succeed in correcting the timeline. Eobard later shows his partners that the completed amulet projects a holographic map that can locate the Spear of Destiny, which is able to "rewrite reality itself". They must next locate Rip Hunter, who is revealed to be working as a movie director in 1967 Los Angeles.

During the New York attack, Rip recovered the Spear from the Waverider and used the time drive to escape. In the present, the team learns about the Spear and arrives in Los Angeles, 1967, when they confront Darhk and Malcolm attempting to kidnap Rip, who has no memories of his previous adventures and is training with George Lucas. Both parties escape; and Rip is arrested by the police. The team abducts him from custody and takes him to the Waverider. Nate and Ray are revealed to have lost their specialties and powers since the aberration caused Lucas to quit filmmaking. While Nate, Amaya and Ray meet Lucas to dissuade him, the others learn that Lucas has a fragment of the Spear. Darhk and Malcolm overpower Amaya's party and forces them to search for the fragment in a dumpster. The others arrive and a battle ensues, during which they recover the fragment and the Medallion; but Rip is abducted by Eobard, whose partners intend to torture him to find the other fragments. Lucas returns to filmmaking; and the team vows to rescue Rip. Meanwhile, Mick tells Stein about his hallucinations, which the latter eventually interprets are emotional, not neural.

In a flashback in Star City 2016 Eobard and Damien recruit Malcolm just hours after the 2016 Damien was killed by Oliver. In the present day the Legion's attempts to extract information from Rip fail repeatedly, exacerbating tensions within the group. Eobard disappears on another errand after insisting on his superiority, assigning Malcolm and Damien to go to a bank in Switzerland, 2025 in order to access a safe deposit box, the number of which Damien found engraved on Rip's tooth. Meanwhile, Martin recruits Lily to help the team decode the amulet. She finds out that she is an aberration, and gets angry with Martin. After a failed robbery, Malcolm and Damien decide to work together against Eobard. The Legends realize that the mystery speedster is Eobard, and that he needs the Spear to undo his removal from existence. Damien and Malcolm return to the bank and break into the vault, finding a record of Rip's memories. They force Eobard to tell the truth about his disappearances. He reveals that Hunter Zolomon, now the Black Flash, has been chasing him after Flashpoint. They manage to trap the speedster in the vault and escape, with Eobard agreeing not to humiliate the duo again. Lily returns home, while the Legion restores Rip's memories, albeit with "adjustments". Rip is then sent to New Jersey, 1776, and apparently shoots George Washington.

Rip has been brainwashed into working with the Legion. The Legends, who felt the timequake, head to Christmas Eve, 1776, to protect Washington. As Sara and Mick escort Washington, Rip and British troops arrive, armed with modern-day assault rifles. Rip disables the team's technology and shoots Sara in the chest, while Mick and Washington are taken prisoner. Jax holds off Rip while a shrunken Ray works to fix the Waverider. Amaya and Nate share a tender moment in the wilderness. Mick learns that Washington will be executed in the morning and formulates an escape plan. Rip uses Sara as leverage to get Jax to give him the Spear fragment before snapping her neck. The Waverider's power is restored and Sara is revived in time to stop an enraged Jax from murdering Rip. Nate and Amaya save Mick and Washington, who goes on to lead his soldiers to victory at Princeton. Amaya tells Nate they should remain friends, and the team celebrate Christmas on the Waverider.

Rip tracks down Charles McNider in the year 3000, killing him and taking his fragment of the Spear. Gideon locates the next fragment in medieval England in 507 A.D. during the age of King Arthur. They are intercepted by Guinevere, who takes them to Arthur. Amaya recognizes his adviser Merlin as Stargirl, her former comrade in the JSA. She explains that Rip divided the Spear into four pieces, and that she formed the Knights of the Round Table to protect hers. The Legion abducts Arthur and uses him to enter Camelot, threatening to destroy it unless the Spear is brought to them. Sara persuades Guinevere to help them fight back, but Stargirl refuses to let them have her fragment. Amaya steals the fragment, which has been forged into Excalibur, but Stargirl catches her in the act. Having fallen in love with Arthur, she entrusts it to them. Upon learning that Ray has joined Guinevere's army, the team devises a way to reverse the Legion's brainwashing, and Arthur subdues Rip. Ray pursues a fleeing Damien and gets shot, but survives due to his suit's armor. Imprisoned in the brig, Rip contacts Gideon, who has been programmed to be loyal to him.

Rip issues an override order to Gideon to activate the Waverider's self-destruct sequence, but the team manages to reboot Gideon and stop it. They crash land in the Cretaceous period and Ray, Amaya and Nate venture out to recover a lost engine part. Mick suggests using a Time Master method of mental programming to travel inside Rip's mind and discover the location of Commander Steel and the final piece of the Spear. Sara and Jax travel inside Rip's mind, encountering evils from Rip's past, evil versions of themselves, Gideon in human form, and a trapped Rip. Ray, Nate and Amaya retrieve the engine part, with Amaya using her abilities to stop a dinosaur from attacking them. Nate and Amaya start to develop mutual feelings, but Ray advises against this, reminding Nate that Amaya's granddaughter will eventually inherit her abilities. Sara, Jax and Gideon free Rip's consciousness before Sara and Jax return to reality. Rip shares a kiss with the human Gideon before returning to reality and resuming his role as Captain, informing the team that he does know the location of Commander Steel and the last piece of the spear. Commander Steel is revealed to be in 1970, posing as John Swigert, Apollo 13's Command Module Pilot, with Eobard Thawne serving as his medical examiner.

The Legends head to NASA in 1970, where Henry Heywood is working as a consultant. Henry reveals that he hid his spear fragment in the flag left by Apollo 11 on the moon, but then reveals that the Apollo 13 mission is going exactly as planned, worrying the team. It is revealed that Thawne has taken the identity of Jack Swigert, as he incapacitates the other two. Ray flies aboard the Apollo command module, and manages to restrain Thawne before retrieving the spear fragment. However, the Waverider is damaged when Sara attempts to stop meteors from damaging the Apollo craft, leaving Ray stranded on the moon. Ray and Thawne eventually launch themselves off the moon and are caught by the Waverider. Thawne is restrained, but does calculate the angle the team needs to reenter the atmosphere. Henry sacrifices himself to save the team, leaving Nate disappointed that he wasn't able to create a potentially better life for his family, but passes on Henry's message to his teenage father. Sara and Rip seem to clash over who should Captain the ship, but eventually reach a mutual agreement. Amaya asks Gideon to show her the fate of her village and her family, revealing to Amaya the destruction of her village and knowledge of her granddaughter Mari, the present-day Vixen.

The Legends steal the remaining fragments from Thawne, making it whole again. Writings on the spear reveal that it can be destroyed by the blood of Jesus Christ. Nate reveals that J. R. R. Tolkien has done a lot of research on Sir Gawain, who possessed some of Christ's blood. They find Tolkien in the Battle of the Somme, 1916. Tolkien takes the Legends to the grave, where they are attacked by Darkh and Snart, whom the Legion recruited before he joined the original Legends. Tolkien acquires a map before escaping with the others. Amaya offers using the spear to erase the Legion from reality, but is opposed by the others. Using the map and the spear, they track the blood to the Somme, where Rip manages to convince both sides for a temporary ceasefire, during which the Legends acquire the blood. They are confronted by Darhk and Snart, who convinces Mick to join the Legion and give them the spear, with which they escape after Snart triggers a conflict, leading to the destruction of the blood. Malcolm returns to the Legion with the Kalabros Manuscript, which they use to activate the spear.

In the new reality created by the Legion of Doom, Eobard Thawne is now the genius CEO of S.T.A.R. Labs and has captured Black Flash, Damien Darhk is the mayor of Star City, Malcolm Merlyn's family is alive, and Snart and Rory control Central City as Captain Cold and Heatwave, but still answer to Thawne as their superior. Ray, Stein and Jax work in S.T.A.R. Labs for Thawne, Sara and Amaya work as enforcers for Darhk, and Nate is a conspiracy theorist. Rip, being the only member of the Legends who is aware of the changes in reality, has given up and now bakes pastries onboard the Waverider. Mick, who is unsatisfied with his easy life of crime, takes Nate to re-assemble the Legends, using Ray's new invention, the reality gun, to restore their memories. Stein, who is abused by Jax in this reality, breaks the gun after the latter attempts to use it on him. They resolve to reclaim the Spear from Thawne before he can use an incinerator built by Stein powerful enough to destroy it, cementing the new reality. Darhk, Merlyn, and Snart also form an alliance against Thawne to reclaim the Spear for themselves. In a fight to retrieve the Spear, Amaya, who attempts to restore reality, is killed by Snart, thus enabling Thawne to destroy the Spear. Now trapped in this alternate reality forever, without their special powers, the defeated Legends make a risky plan to stop the Legion from ever getting the Spear in the first place, by travelling back to 1916 and preventing the Spear from being taken. Elsewhere, Rip and the Waverider are revealed to be miniaturized in Thawne's office.

The Legends regain contact with the Waverider and Ray deminiaturizes both it and Rip. The Legends travel back to the battle of the Somme to steal the Spear before the Legion can use it, while Thawne arrives from the altered reality and kills future Ray by tearing his heart out before destroying the blood of Christ and informing the past Legion members about the future Legends. The Legends end up interacting with their past selves, creating a time storm that prevents them from using the past Legends' Waverider to escape when they are ambushed by Merlyn, Darhk and Snart. During the subsequent battle, the future Legends, with the exception of Sara, are killed by the Legion, before they are in turn incapacitated by the past Legends. Thawne arrives with multiple past versions of himself to fight the team, while Sara begins to use the Spear to rewrite reality. After speaking to a manifestation of Laurel, Eobard takes and attempts to use the Spear against the team, only for Sara to reveal that she made the Spear defunct and that she released the Black Flash, who kills Eobard and erases him, his past versions, and the Spear from existence. With the mission complete, future Sara fades out of existence. Nate convinces Amaya to stay. The Legends drop off Merlyn at his apartment in 2016, and erase Darhk's and Snart's memories, dropping them off in 1987 and 2014 to live out their destinies and eventual deaths. Rip leaves the team, telling Sara that he has taught her everything. The Legends set off for Aruba, 2017 at Mick's request, but find themselves in Los Angeles, 2017 which, due to their meddling in time, now has buildings from different time periods and is swarming with dinosaurs.

In the altered Los Angeles, the Legends encounter Rip, who reveals that he has created the "Time Bureau" to replace the Time Masters' Council. Bureau agents fix the "anachronisms" and Rip disbands the Legends. Six months later, the Legends are living normal lives, nostalgic for their previous adventures. In Aruba, Mick captures Julius Caesar and informs Sara, who takes Ray and Nate on a quest to prove their worth to the Bureau. After delivering the wrong man and being dismissed by Rip, the Legends, joined by Jax and a reluctant Stein, steal the Waverider and capture the real Caesar. When Rip demands they deliver Caesar to the Bureau and let the Bureau fix the anachronism, the Legends choose to return Caesar to 49 BC themselves. During the return, Caesar steals Nate's history book and uses this knowledge to conquer the world. The Bureau arrives and seizes control of the operation. During an excursion to retrieve the book, Agent Sharpe is captured, forcing Rip to allow the Legends to fix the anachronism. Later, Rip tells Sharpe that the Legends could be useful in neutralizing "Mallus." In 1942 Zambesi, Amaya, with significantly improved powers, attacks a group of poachers.

Six months ago, Amaya learnt of Mari's vigilantism and suddenly left Nate. In the present, the Legends head to a petty anachronism in 1870 Wisconsin, when they come across a circus fronted by P.T. Barnum, who has captured an extinct sabertooth tiger. Ray's shrinking device malfunctions, leading to the enlargement and escape of the sabertooth. Sara visits Amaya and convinces her to return, much to Nate's displeasure. While Nate, Ray, and Jax visit an inn, Amaya and Sara shrink and capture the sabertooth. Intoxicated due to his depression over his relationship with Amaya, Nate tells Barnum about their powers. Intending to use them for his shows, Barnum captures Ray and Jax while Nate informs the Legends. Amaya tells him that she had to leave 2017 in order to preserve Mari's existence. While Sara engages with Sharpe on the Waverider, the Legends attack the show and rescue their teammates, removing the anachronism. Nate reconciles with Amaya, who tells the Legends that she has begun to lose control of her animal powers, resulting in psychopathic behavior. Sara tells the Legends about the Mallus threat, which they do not take seriously considering their previous accomplishments. A follower of Mallus summons Kuasa, Mari's sister.

In Seattle, 2042, Time Bureau Agent Gary discovers hydrokinetic assassin Kuasa pursuing Zari, a hacktivist, and sends a distress signal. The Legends receive it and find Seattle under martial law imposed by A.R.G.U.S., which is hunting down metahumans. They find Zari, who demands help in rescuing her brother from prison in exchange for finding Kuasa. Amaya is uncertain about her powers, so Stein and Nate seek a solution, with Nate synthesizing a Zambesi hallucinogen. She uses it to have a vision with an ancestor, who advises her to trust the increasing strength. While Jax initiates an unplanned prison break, Zari retrieves her brother's amulet, admitting his murder by A.R.G.U.S., and ditches the team. Ray pursues her to a campsite where her family was to rendezvous. Kuasa attacks the duo while Sharpe pursues the Waverider in the timestream. The Legends arrive and Amaya, now in control of her powers, defeats Kuasa, who vanishes using a mystical item and implies she is a descendant of hers. Sharpe warns Sara that, if the Legends are arrested, they would be banished to the "dawn of time." Amaya decides to stay and recruits Zari to the team. In 1988, a young Ray encounters an unknown creature.

Ray suddenly disappears from the Waverider and Gideon reveals that he died around Halloween of 1988. The Legends travel to 1988, when Ray reappears and finds his younger self has adopted a baby Dominator. Eventually, N.S.A. agents take the baby Dominator, leading Ray, young Ray, and Zari to break in and rescue it while Sara, Nate, and Amaya discover the Dominator's mother has returned to retrieve her child. The baby uses mind control to distract the agents and the Legends get it back to its mother, who leaves in peace. When young Ray gets picked on by bullies on Halloween, the Legends show up and defend him. Meanwhile, Jax and Mick learn that Stein is anxious to be present for the birth of his grandchild and help him with it, "borrowing" the Waverider. Later, Jax asks Ray to help him figure out a way to split Firestorm so that Stein may have a normal life.

Nate discovers a pattern to the anachronisms, with two "outliers": Kuasa's attack and a suspected vampire attack in Victorian London. The Legends arrive and meet up with Rip, who is investigating a conspiracy involving Mallus, an ancient archenemy of the Time Masters; he believes that the outlying anachronisms are examples of Mallus' work. They discover Darhk's body – which apparently fell through a temporal rift into this time period – and Zari encounters a follower of Mallus, Madame Eleanor, who steals her amulet while working with a Victorian occult society that includes Stein's ancestor, Sir Henry Stein, among its members. Rip traps the Legends aboard the Waverider to protect them before attending Darhk's resurrection, which Eleanor achieves using the amulet. The Legends arrive and engage Darhk and Eleanor, but they escape. Sara reports Rip to the Bureau and they promptly arrest him in exchange for re-legitimizing the Legends. Rip warns Sara about Mallus' importance. Meanwhile, Jax has Ray attempt to sever his psychic connection with Stein as a precursor to breaking their physical link as Firestorm, but suffers a side effect of short-term memory loss. Stein finds out and eventually decides to help them.

Martin, Jax and Ray attempt to transfer Firestorm to Jax. It fails and causes a body swap. The Legends track an anachronism to 1937 Hollywood, revealed to be Helen of Troy. While attempting to extract Helen at a party, the team encounter Darhk, Eleanor, and Kuasa. Darhk tells Sara that he will spare the Legends' lives if they cease time travel. Meanwhile, Stein meets Hedy Lamarr and the other male Legends start a fight over Helen. The female Legends privately confront Helen. She refuses to return to Troy, citing the misery of men dying over her. The female Legends eventually obtain Helen. The Waverider breaks down. Lamarr's switch from actress to operator means she no longer invents FHSS. To fix this, Stein goes to Lamarr's workplace which results in a confrontation with Darhk. Amaya and Zari guard the Waverider while the remaining Legends assist Stein. Sara duels Dahrk while the remaining Legends are beaten by Eleanor. Lamarr tells Jax and Stein to merge which will allow them to return to their bodies. Firestorm defeats Darhk and Eleanor. On the ship, Amaya and Helen defeat Kuasa. The three retreat. A sympathetic Zari takes Helen to Themyscira instead of Troy.

With Sara still in a coma, the Legends choose to investigate creature attacks during the Vietnam War. Zari, Ray, and Amaya, posing as journalists, meet a woman who shows them the creature, revealed to be a time displaced Gorilla Grodd. Meanwhile, Nate and Mick are captured by a squad led by Mick's father, Dick Rory.[7] On the Waverider, Stein discusses how to separate Firestorm with Isaac Newton. Jax walks in on their discussion and learns that Firestorm can be separated, but it would depower Jax. The anachronism increases in intensity, revealing Grodd's plan to wipe out humanity by killing President Johnson and starting World War III. Jax, inspired by a powerless Sara's abilities, saves Johnson from a minefield. After failing to capture Grodd, Amaya uses her powers to negotiate with him, but is thwarted when Dick's squad attacks. Grodd decides to steal the Waverider and wipe humanity from the timeline. His attempt fails and he seemingly falls to his death. Back at Grodd's compound, Mick stops his father from massacring Grodd's prisoners and comes to terms with his relationship with his father. The team returns to the ship as Sara emerges from her coma. In 2017, Grodd is approached by Darhk.

On Earth-X, Stein activates the temporal gateway's portal before succumbing to his injuries. Jax bonds with Stein to get him through the portal, along with Barry, Oliver, Sara, Alex, Ray Terrill, and Leo Snart (Leonard Snart's Earth-X doppelganger). Members of all the teams face off against Earth-X Metallo, while Felicity and Kara are cornered by Dark Arrow before Oliver saves them. Jax is also affected by Stein's wounds; Stein severs their link and dies. Dark Arrow attempts to negotiate for Kara, but Oliver refuses and the team battles Dark Arrow's forces. Caitlin, Amaya, and Zari infiltrate the Nazis' timeship Wellenreiter to disable its shields so that Harry and Cisco can destroy it with the Waverider. Barry defeats Thawne, but allows him to escape, resuming their feud. Supergirl battles Overgirl, flying her into space to detonate away from the Earth when she goes nuclear. Oliver fights and kills Dark Arrow. Terrill returns to Earth-X, but Snart chooses to stay for the meantime and joins the Legends. The team holds a funeral for Stein. The Legends, Kara, and Alex depart back to their own lives. Barry and Iris are officially married by John Diggle, who also marries Oliver and Felicity.

The team tracks down another anachronism, which turns out to be a young Martin Stein displaced in the time of the Vikings. Martin was buying a talking Beebo toy as a Hanukkah present for his daughter when he was displaced, causing the Vikings to believe that Beebo is the God of War. Damien Darhk shows up, worrying Sara, but the team eventually manages to set time right again. Jax attempts to tell young Stein of his future self's death, but Stein had already deduced it based on his counterpart's absence. Stein, not wanting to cheat death and aware that he has a wonderful future, decides not to learn the details of his impending death, accepting his fate and resolving to spend the years he has left dedicated to his loved ones. With the present Stein dead and his Firestorm powers gone, Jax chooses to leave the team, but not before an impromptu Christmas celebration. Sara and Jax part on good terms and Jax departs for new pastures. On returning to the Waverider, Sara is greeted by John Constantine, who claims that he needs her and her team's help with a demon who knows her name and is controlling a little girl.

John Constantine explains to the Legends about the demon, which Sara reveals to him is Mallus. While John insists they leave it to him, Sara proclaims that they are coming as well. The little girl is Damien Darhk's daughter Nora, and is being held in an insane asylum in 2017 and while they try and help Nora she is possessed by Mallus and sends the trio of Sara, John and Leo to 1969. While possessed by Mallus, Nora is revealed to have extraordinary abilities, prompting Sara to once again enter Mallus' realm to rescue Nora while trapped in 1969 and they try to recreate the symbol that Mallus created that sent them through time to successfully return home. Nora is promptly reclaimed by Damien Darhk, claiming she will soon be used for his full resurrection. With the demon dealt with, Constantine departs from the Waverider, thanking Sara for her help. Leonard also departs, thanking Mick for the adventure. Sara calls up Ava to compare notes, only to be told by Ava that Rip Hunter has escaped from the Time Bureau. Throughout this episode, Amaya tries to talk with Kuasa, but when Nate intervenes, a fight breaks out, which ends in her escape.

A mission goes wrong, causing the crew to yell at each other. Zari attempts to repair the ship, but gets covered in goo and seemingly activates a program that blows up the Waverider, before seemingly re-experiencing events from earlier that day. The day seemingly keeps repeating, with Zari experiencing the same events over and over, learning mysterious secrets about the team, such as Mick's writing ability. Eventually, the team discover Time Agent Gary on board, who has been causing the repetitions. Mick destroys Gary's device, but Gary tells them the repeats were the only thing saving them from death. When the ship is next set to explode, Zari seals herself in the study and uses her powers to try and contain the blast. She reappears in an empty Waverider, where she encounters Gideon's human form, who reassures her that she's in the med bay and alive. She tells Zari that she transported her into her program to show her she can't save 2042 without the Legends. Zari admits to Sara that she was researching historical loop holes to see if she could save her brother, which Sara reassures her might be possible. In Yunnan Province, China, the recently escaped Rip Hunter tracks down Wally West.

The team reviews the list of totems and decides to find the Fire Totem first; however, Damien Darhk retrieves it first, making it a tie where each side has two totems. Sara goes on a date with Ava. While she is away, the team takes the Waverider to 1700s Bahamas, landing in the Bermuda Triangle. There they encounter a pirate crew, led by Edward Teach, which includes Darhk, who steals Amaya's totem. After learning of the team's trouble, Sara abandons her date with Ava to help them. The Waverider is attacked by cannonballs and boarded by Blackbeard and his crew, though Ava comes to help Sara fight them off. Most of the team escapes; however, Ray wracked with guilt, returns in hopes of making up a wrong he did towards Nora Darhk, in exchange for Amaya's totem. Ray is captured by the Darhks. Wally helps Rip neutralize a Time Agent, and gets Rip's trench coat back from the Time Bureau. The two get drunk and sing karaoke in 1992. Rip tells Wally that maybe it's time he went out to seek adventure.

Damien instructs Nora and a hostage Ray to travel to 1962 Berlin to retrieve information about cold fusion, which can be used to fix the Fire Totem. Rip brings Wally to the Legends, and they try to work out their next move. Nora corrupts Amaya's totem, and the Legends learn that the Darhks are creating anachronisms to weaken Mallus' cage to eventually free him into the world. Damien saves Nora from his younger self, and she gains control over the totem. When cornered by Nora, Ray blasts a hole in the Berlin Wall, causing another anachronism, allowing the Legends to locate him. Wally rescues Ray and takes the Fire Totem. Director Bennett is murdered by Grodd, making Ava the senior officer at the Time Bureau, allowing Rip to return to work. Wally intends to go with Rip and Ava, but Sara convinces him to stay with the Legends, which Rip congratulates him on. Before leaving, Rip instructs Gideon to delete Ava's file, claiming Sara must never know Ava's secret. Mallus gains control over Nora behind Damien's back.

Wally moves into the Waverider, and proceeds to annoy everyone with his superspeed. The team soon discover differences aboard the ship, such as Nate's hair, Mick's rat's name and Zari's game. Tracking the anachronism, they find that mass panic was caused in Memphis in 1954, during a performance by Elvis Presley. Once there, they discover that Presley's guitar contains the final totem, the Death Totem. Things start to go wrong, when Presley admits he might be considering quitting music after the death of his brother. The team bring the guitar back to the Waverider, but start seeing a ghostly presence. Eventually, they are able to secure the Death Totem, and convince Elvis to continue pursuing music. Amaya plays Nate some music from Zambesi. The sealed box containing the Death Totem seems to shake.

Sara is enticed to open the box and wear the Death Totem, her body once again falling under the control of Mallus, while her mind is trapped in his realm, with a vision of Nora. The team try to fight her off, but her new mystical abilities prove difficult to contain. Upon learning of Sara's situation, Ava and Gary track down John Constantine to try and help. Meanwhile, one by one the legends try to stop Sara, but are each taken out, leaving Nate, Amaya, and Rory to stop her. While in Mallus' domain, Sara sees visions of what made her the woman she is at the same time as Nora tries to convince her to join Mallus. Nate tries to get to the Earth Totem to use it, but is confronted by Sara, and defeated. Learning that Sara is using the Death Totem, John attempts to enter Mallus' realm, but Mallus blocks him. Mallus tries to trick John into sacrificing Sara to save the little girl Astra, but John sees through the ruse. Amaya convinces Mick to wield the Fire Totem, which is enough to stun Sara, allowing Constantine and Ava to release her from Mallus' control. Fearing that she might hurt Ava, Sara breaks up with her in order to protect her.

Sara contemplates leaving the team after her breakup with Ava, only to find out from Gary that Ava hasn't been to work in a few days. Sara, Ray and Gary travel to Ava's home, only to find that Ava's parents are actors, paid to play a constant role. The three travel to 2213, where they find Ava is actually a clone mass produced by a conglomerate. The three are apprehended by multiple Ava clones, but are saved by the original Ava. Zari teaches Mick to use the Fire Totem. Amaya, with a temporary truce with Kuasa, manages to reclaim her totem, but Nate is captured and "tortured" by Damien Darhk. However, it is revealed that Darhk misses how his little girl used to be before Mallus. He is later caught by his daughter faking the torture. Amaya, Wally and Kuasa rescue Nate and confront Nora, but Nora rips the Water Totem out of Kuasa, killing her. Driven by grief and guilt, Amaya goes back to 1992 Zambesi to change her family's fate. Ava and Sara realize Rip deleted Ava's file from the Bureau and decide to find out why.

The Legends stop Gorilla Grodd from killing future president Barack Obama in the 1980s, preventing another anachronism and further delaying Mallus's release. Damien realizes that Nora will be killed when Mallus is released from his prison, causing him to temporarily ally himself with the Legends. By getting actor John Noble to impersonate the voice of Mallus, the team tricks Nora onto the Waverider and contains her. Ava asks Rip if he knew that she was a clone; Rip reveals that she is the 12th Ava clone he has recruited, because she is such a talented agent. Amaya returns to 1992 Zambesi to change history and secure her family's future. Nate, rather than try to convince her to return, elects to help her instead. Sara decides to allow this to happen, causing the final anachronism that will free Mallus, having concluded that the only way to stop the demon is to release him. She gives Damien the Death Totem, while the rest of the team chooses to wield their own individual totems. Damien realizes that Nora is still alive within Mallus and releases Grodd to destroy Zambesi, preventing Mallus' release. Nate subdues Grodd with the Earth Totem. Mallus breaks free from his prison, revealing his frightening true form.

Mallus demands the Legends hand over the six totems. Rip sacrifices himself to allow the team to get away, fleeing to the town of Salvation in the Old West. An army of Romans, Vikings, and pirates soon arrives, threatening to destroy the town unless the Legends surrender the totems. Ray and Damien travel to when Mallus was released from Nora; Damien frees Nora from Mallus' hold, causing Mallus to possess and kill Damien in order to be released. Back in the Old West, the Legends ally with Jonah Hex, along with Helen of Troy, Jax, Nora, and an alternate Kuasa. The team saves the town from the army. Mallus arrives for the totems; Sara, Mick, Amaya, Nate, Zari, and Wally combine the totems' energies to create the ultimate warrior: an enlarged Beebo. Beebo battles and kills Mallus. In the aftermath, Nora is arrested by the Time Bureau, but Ray gives her the Time Stone so that she can escape. Amaya returns to Zambesi in order to live her life, but chooses not to wipe her memories. The Legends' vacation in 2018 Aruba is interrupted when John Constantine arrives, revealing that Mallus was not the only demon that was released.

The Legends and the Time Bureau celebrate a job well done, with Zari chastising Ray for allowing Nora Darhk to escape. Ava and Sara rekindle their relationship together. John Constantine tries to warn Sara about the darkness coming, but Sara dismisses him claiming that they have searched the timeline and nothing is out of place for five months. The Legends end up at Woodstock where they see an unicorn impale someone and eat their heart. It then releases magical goo at Mick, Ray, Nate, and Zari, making them hallucinate. Realizing he was right, Sara locates Constantine and informs him of the situation, and they make a counter-drug against the unicorn's goo and cure the affected Legends. The unicorn will feast on the flesh of a virgin, so Constantine and the Legends use Time Bureau member Gary as bait to lure the unicorn before Constantine uses a spell to send the unicorn to hell. Meanwhile, Nate and Rory go an adventure leading to Nate attempting to reconnect with his distant father. Back at his accommodation, Constantine experiences a dark form of magic throwing him about the place, before it writes in blood that it is coming for him.

The Legends wire up the magical detection bones into the Waverider to allow them to track magical fugitives. Constantine joins the Legends as a magical consultant, with their first mission leading them to the Salem Witch Trials. When an innocent woman is accused of witchcraft, her daughter's Fairy Godmother attacks the townsfolk. Zari fights to save the mother, who was executed in the original history, while Constantine and the Legends try to separate the daughter and the Fairy Godmother so Constantine can banish her to hell. However, the Fairy Godmother turns Ray and Mick into pigs and seals Constantine's mouth shut, but when the daughter releases her, the Legends return to normal. Once they succeed, Constantine offers the Fairy Godmother the chance to be her new magical conduit, but she refuses, knowing what's in store for him, so he sends her to hell instead. Nate discovers his father is overseeing the committee that funds the Time Bureau and struggles to prove that magic is real so the Bureau will stay funded and open. He is able to do so when Ray turns back to normal in his arms. Ava offers Nate a place at the Bureau and Nate accepts.

The team track another magical fugitive to London, with a new punk rock band favored by the queen, called "The Smell." Constantine hypothesizes that the fugitive is a leprechaun, and is posing as a member of the band. The team attempt to scope out The Smell, with Ray earning their trust by stealing one of the Queen's prized corgis, and discovers that instead of a leprechaun the fugitive turns out to be a shapeshifter and the band's lead singer Charlie. Fearing imprisonment, Charlie knocks Ray unconscious (despite him preparing to defend her) and steals his A.T.O.M. suit, using it to try and kill Sara, Zari, Mick, and Constantine when they attempt to catch her and banish her to hell. Eventually, Ray wakes up and saves the group by dismembering his suit via voice activation, and Charlie is caught. However as Constantine attempts to banish her, she shapeshifts to resemble each of them and ending with Amaya while calling them out for not acting like heroes, causing Zari to feel sympathy for it. Out of annoyance, Constantine casts a spell that renders Charlie unable to shapeshift ever again, leaving her trapped in Amaya's form. They decide to keep her as prisoner on board the Waverider.

Ava briefly joins the team to help with an investigation into kids disappearing at a summer camp in 1995. The team pose as camp councilors, while they track down a swamp creature that has been kidnapping the kids. Ava and Sara take a potion that turns them into children in an attempt to lure the creature out. Charlie attempts to escape the Waverider, but is stopped and comforted by Mick. The team are able to locate the monster, known as a Shtriga, and its victims. John uses a spell to banish the Shtriga, but one of the kids remains unresponsive. John uses another spell to heal the child, and he is revived, though John is injured. Ray and John are subsequently rescued by the campers. Charlie agrees to help the Legends, officially joining the team, on the condition that they do not lock her up again. Gideon cannot save Constantine, but Ray claims to know someone who might be able to. Nora Darhk is revealed to be working at a Renaissance Fair.

With Constantine still injured, Sara has Gideon look for Nora Darhk in 2018, with Gideon quickly finding a match. Ray goes to find her at a Renaissance Fair, to ask for her help in saving Constantine. Nora agrees and is able to use her magic to heal him. Ray tells her to run and not to tell them where she went, but Nora uses the time stone to travel to the Time Bureau, wishing to repent for her actions. The other Legends meanwhile investigate a fugitive in 1950s Tokyo, discovered to be a giant Octopus creature that has appeared on a film set. The creature, named Tagumo, was brought to life by a magical book, which used the imagination of the filmmaker. Sara and Charlie manage to partially shrink it, but the Tagumo still attacks the set. Mick uses the book and his own imagination to create a heroine named Garima that battles the Tagumo, eventually defeating it. The Legends confiscate the book. The fugitives almost escape the Bureau, but Nate and Gary manage to find a way to contain them with food. Ava joins the Heywood family for Thanksgiving. In secret, Hank tells someone the fugitives are controllable and gives them permission to execute "Project Hades".

Nate invites Hank to the Waverider and gives him a tour on the ship. The Legends attempt to keep Nate from Charlie, because she looks like Amaya, but fail. The Waverider detects a fugitive in Paris, 1927. Ray visits the Bureau in an attempt to see Nora but Ava rejects the visitation although Mona sneaks in a letter to Nora from Ray which Nora refuses to read and triggers her. This grabs the attention of Ava who tries to restrain Nora but they end up getting locked in the prison cell. The Legends are joined by Ernest Hemingway to hunt for the fugitive who appears to be a Minotaur. During the fight with the Minotaur, Hank is injured. Nate and Constantine calm the Minotaur down but Hemingway attacks it, angering the Minotaur. Nate confronts the Minotaur who prevents his Steel powers. Hanks picks up the guitar and sings the Minotaur to sleep. Meanwhile, Ray rescues Mona, Ava and Nora. Ava shows humanity in the prisoners thanks to Mona. Nate officially leaves the Legends team.

The Legends travel to New Orleans in 1856 to track down a fugitive relating to a series of murders. Sara, Ava, Ray and Mick head off to find the fugitive, while John, Zari and Charlie scope out the local area. Constantine has a history with the city, where his former lover Desmond made a deal with the demon Neron to protect him and was subsequently sentenced to hell. The team manage to hunt down the serial killer Mike the Spike, but his consciousness is transferred into the Martin Stein puppet, which stalks the team. Constantine travels back to 2018 and changes history so that Desmond does not fall in love with him, but this causes a ripple effect, freezing the Legends aboard the Waverider, breaking the lock on Charlie's shapeshifting abilities and transforming Zari into a cat.

In the new timeline, Constantine never joins the Legends and as a result Sara is killed by the unicorn at Woodstock, leading to Mick, Nate and Ray forming a new violent version of the Legends called "Custodians of the Chronology". Charlie breaks Constantine out of the Time Bureau and together they return to Woodstock and kill the unicorn. Upon returning to 2018, they discover that Mick, Nate and Ray have been killed by the Fairy Godmother, while Sara, Ava and Gideon have formed "Sirens of Space-Time". Another attempt to fix this sees Mick bond with the Fairy Godmother to begin a new criminal career while Sara, Ray and Nate are now the "Puppets of Tomorrow". After several more failed attempts to fix the timeline result in various other Legends or their allies being killed in increasingly bizarre ways, the restored Zari convinces Constantine to return to New Orleans and restore the original timeline with Desmond. Constantine tells his story to Sara, who agrees to help him battle Neron. Hank is shown golfing with a creature wearing Desmond's face.

Mona is blamed for Konane's escape and is fired from the Time Bureau. She evades a mindwiping, meets Konane and sends him back in time before being captured by the Legends. Nate and Zari look into the footage of Konane's escape and find it has been altered by Hank. They recover the original footage from Hank's phone, confirming Mona's version of events. Nate confronts his father, pretending to be on his side. Meanwhile, the rest of the Legends find Konane in 1961 Mexico City as a professional wrestler named "El Lobo", having overshadowed another wrestler named "El Cura". In order to preserve the timeline, they plan to have El Lobo lose to El Cura in a Lucha de Apuestas. Sara confronts Ava about Nate and Zari's suspicions, but she does not believe her and has her team go after Konane. In 1961, El Cura reclaims his old glory by helping the Legends stop the Time Bureau from capturing Konane. Ava breaks up with Sara. Mona is preparing to send Konane back to his time when a Time Bureau agent finds them and shoots Konane dead. An enraged Mona turns into a Kaupe and kills the agent, before turning back into a human.

With Ava on leave, Hank assumes Time Bureau directorship and tries to apprehend the Legends. Nate and Zari feign working with him, but secretly help the Legends escape. In 1973, the Legends, while on the run with Mona, remove a roach, an agent of Ma'at, from Richard Nixon that has left him unable to lie. The roach enters Sara, who blames her breakup with Ava on Mona, causing her to run away. Sara and Constantine follow her and after a battle with her "Wolfie" form, calm her down, making her part of the Legends. Meanwhile, Gary and Nora are brought in on Nate and Zari's conspiracy. They hack Hank's email, but are interrupted by "Desmond", who informs Hank. Hank realizes Nate has deceived him and uses him to capture the rest of the Legends. The roach enters Nate, who confronts Hank about his feelings, leading to Hank promising to trust the Legends henceforth. At the bureau, Hank attempts to sever ties with "Desmond", who responds by killing him. In her cell, Nora senses the danger, breaks out and rushes to Hank. Nate enters the room, finding Nora kneeling over his dead father. She tries to explain herself, before using her powers to escape.

The Legends are at Hank's wake when they get an alert that a magical creature has gone after Jane Austen. The women travel to 1802 and attend a wedding where everyone goes crazy with love. Zari captures Sanjay, who can cause love and lust with Hindu god Kamadeva's ashes, but fails to fix the anachronism. Ray hides Nora onboard the Waverider after she proclaims her innocence in Hank's death. Sanjay uses the ashes to give the Waverider crew intimate dreams. Mona dreams about Konane and gets into a fight with Zari over their differing views on romance. She turns into Wolfie and goes after Austen for making her a romantic, while Zari takes another dose of Sanjay's ashes. Austen talks Mona out of losing control and she rushes to stop Zari from marrying Sanjay. Meanwhile, at the wake, Nate is initially upset with his father and plans to expose him, but later discovers that he was not torturing the magical creatures, but was training them for a theme park Nate had drawn when he was nine. Constantine senses Hank's spirit and pulls it into Mick's body. Hank tells Constantine he has been working with Neron, who then appears, taunting Constantine.

Nate and Ray locate Hank's theme park construction site. Initially wanting the site torn down, Nate eventually changes his mind and has the construction continue. The rest of the team discover Ava has been abducted by Neron. Using Nora's connection to the demon, they track Ava and find her unresponsive. Constantine believes Neron is preparing Ava as his new vessel and agrees to send Sara to reclaim her soul from her personal Purgatory, which takes the form of a supermarket with Ava products. Ava and Sara solve their relationship issues and find a way out. Meanwhile, Charlie, Constantine and Nora ambush Neron and capture him. Neron tempts Nora with reviving her father if she agrees to become his new vessel, while also revealing he needs a second vessel for someone called Tabitha. Nora seemingly agrees, but when Neron leaves Desmond's body, he is trapped by Nora and Constantine. However, Constantine loses focus when a concerned Ray rushes to the scene, leading to Neron and Nora zapping each other before the former disappears, leaving the latter unresponsive. Desmond wakes up, but leaves Constantine, upset about being sent to Hell. While Constantine believes Neron is dead, the demon is actually now inside Ray.

Sara tries to get Nate and Zari romantically involved by having them go after a fugitive in 1933. They infiltrate the Adventurers' Society, where Gordon Gilchrist reveals his discovery of a golden egg. After Nazis show up looking for the egg, Ava and Sara join the mission, capture the egg and bring it onboard the Waverider, where it is revealed as a dragon egg. Meanwhile, Ray discovers Neron is inside him and tries to resist his control. Neron looks to seal the possession by having Ray murder a loved one, first targeting Nora and then Nate. Constantine uses a spell to awaken Nora, who reveals that Neron controls Ray. Neron gains full control of Ray when he offers to stop resisting to save Nate's life. Gary, feeling unappreciated by both the Legends and the Time Bureau, accepts his nipple back from Neron and falls under his control. He and Ray teleport away, taking Constantine with them. Ava recruits Nora as part of the Time Bureau to help take down Neron.

Neron threatens to kill Ray unless Constantine opens a portal to hell for Tabitha. The Legends track Constantine to the ice age, but are trapped in an avalanche, while Neron and Constantine relocate to 55 BCE Stonehenge to meet John's ancestor King Kon-sten-tyn, a mage responsible for the rift between humans and magical creatures. Constantine confronts his ancestor for threatening to send an innocent Púca to Hell and tries to enlist his help against Neron, but the king has him apprehended for practicing dark arts. The king opens a portal to Hell, which Constantine stabilizes to save the Púca. The Legends work together to break free from the ice and travel to Stonehenge in time to stop Constantine from killing Neron and condemning Ray to an eternity in Hell. Constantine decides to save Ray and enters the portal, which Neron then uses to bring out Tabitha, revealed as the Fairy Godmother. Meanwhile, Gary uses his nipple's hypnotizing powers to take over the Time Bureau. Mona turns into Wolfie and bites the nipple off, before Neron and Tabitha arrive. Tabitha turns Wolfie back into Mona, whom she, Neron and Gary then kidnap. Nora chases after them, while Ava alerts the Legends.

The Legends' attempt to reclaim the Time Bureau is interrupted when Tabitha begins granting Gary's wishes, occupying Ava, Mick, Nate and Sara. Neron launches a phone app to track magical creatures, using Mona to publicly prove their existence. Charlie and Zari discover that anyone who downloads the app surrenders their soul to Neron. After regrouping at Zari's childhood home, they infiltrate the Time Bureau to save the magical creatures that Neron plans to use to create buzz for his app. The creatures are saved, but Charlie is captured. Tabitha is freed from having to obey Gary when she tricks Nora into becoming the new fairy godmother. Gary accepts the Legends' apologies and sends his fairy godmother, not realizing it is now Nora, to Hell to save Constantine and Ray. Meanwhile, Constantine discovers Neron is attempting to take over Hell. He seeks out the Triumvirate and offers to stop Neron from usurping them in exchange for the souls of Astra and Ray. Having to choose between the two, Constantine chooses Astra. However, Astra, having grown up in Hell, turns him down and leaves him to be tortured. Meanwhile, the dragon egg, accidentally left in Zari's home, hatches in young Zari's possession.

Neron and Tabitha cause mass panic by turning Charlie into Tagumo in public. The Legends save Charlie, who reveals that Neron wants to unleash Hell on Earth by opening a portal powered by fear. Meanwhile, Nora saves Constantine and they recover Ray's soul from the "Soul Exchange" with Astra's help. They return to Earth, but Ray is stuck until Neron leaves his body. Seeing how popular her dragon has made young Zari inspires the Legends to open Heyworld, Hank's theme park. Neron and Tabitha crash the opening and while Tabitha is eaten by Zari's dragon, Neron uses the crowd's fear to open the portal. Constantine and Nate trick Neron into killing Nate, therefore breaking his word to Ray. Neron is ejected from Ray's body and killed by Constantine, who then closes the portal and revives Ray. Nate reunites with his father in the afterlife, before being revived with Tabitha's staff, powered by love. By teaching tolerance, the Legends erase the dystopian 2042 from history, resulting in Zari being replaced by her previously dead brother Behrad with only Nate sensing that something has changed. In hell, Astra offers the 16 evil souls that she secretly stole from the Soul Exchange a second chance.

Waking up in the newly recreated universe, the Paragons discover they are the only ones who remember the Crisis and that Earth-38 and Jefferson Pierce's Earth were merged with Earth-1 into a composite universe, later designated as Earth-Prime. Not only that, Oliver Queen's second sacrifice gave them all fresh starts. While J'onn J'onzz uses his psionic powers to restore their allies' memories, Sara Lance attempts to find Oliver, though without success. Later that night, the Paragons are attacked by shadow demons. A restored and remorseful Nash Wells discovers that the Anti-Monitor is still alive and plotting to renew his destruction of the multiverse. To stop him once and for all, Nash, Ray Palmer, Barry Allen, and Ryan Choi work to develop a bomb to shrink the Anti-Monitor for eternity while the other heroes distract him. Once it is finished, Kara Danvers uses it on the Anti-Monitor and sends him to the microverse. Sometime later, Barry, Kara, Sara, J'onn, Jefferson, Kate Kane, and Clark Kent hold a memorial service for Oliver before agreeing to work together to protect their new world in his memory.

This episode concludes a crossover event that begins on Supergirl season 5 episode 9, and continues on Batwoman season 1 episode 9, The Flash season 6 episode 9, and Arrow season 8 episode 8.

Following the events of Hey World and Neron's defeat, the Legends have become public heroes. With the Time Bureau dismantled, Ava Sharpe joins the Legends and allows a documentary crew to film them so they can raise funds. Sara, Ray, and Mick Rory return from the Crisis, but Sara has yet to come to terms with Oliver's death.[a] Suddenly, a timequake takes place, leading the Legends to 1917 Russia, where Grigori Rasputin has returned from the dead. The Legends fail to convince Rasputin to kill his killer, so they return to the Waverider, but leave a crew member behind. As a result, the Legends form a plan to stop Rasputin and rescue the crew member before returning to 2020. They then release the documentary to the world, before claiming the film was faked. Meanwhile, in 2020, John Constantine and Gary Green investigate a demon named Masher, who possessed a child in Star City. Constantine performs an exorcism, freeing the child and sending Masher back to Hell. Constantine also returns to Hell, Mick quits writing and passes on his career to Mona Wu, and Nate sees an old message from Zari Tomaz, asking him to find her in the new timeline.

The Legends head to 1947 where mobster Bugsy Siegel has been revived, with Mona coining the term "Encore" for these revived individuals. With his new lease on life, Bugsy plans to make it to the top in the world of crime by becoming an information broker. He also gets revenge on his killer, using a gun loaded with hellfire bullets to destroy their body and soul. Meanwhile, Constantine poses as a detective to deal with Bugsy's ex-girlfriend, who is after a bag of money the thug buried. Despite causing chaos, the Legends capture Bugsy, whom Constantine uses to return to Hell and kill him with his own Hell Gun before warning Astra Logue, whom he accidentally sent to Hell, to stop. Meanwhile, Nate and Behrad Tarazi return to the latter's home time and town for dinner, where they find Zari has become an internet celebrity. Nate and Zari almost connect when she realizes that they were both at Hey World and have not aged a day, but she threatens to tell her parents about this when Behrad and Nate open a time portal back to the Waverider.

Ray believes the Encores can be stopped by reforming them in the past. The Legends test this idea when executed serial killer Freddy Meyers is encored in 2004 and attacks his high school reunion. Sara, Ava, and Mick head there to stop him while Ray, Nate, and Behrad take Nora Darhk to 1989 to become Freddy's fairy godmother and fix his prom night. The Legends find evidence of a prank that Freddy's date, Tiffany, and a jock were going to pull, but the former has a change of heart and gets the latter to confess. With Nora's encouragement, Freddy uses his last wish to perform a dance number to show his "true self". Zari has flashes of her life as a hacker and escapes the Waverider just as the real killer attacks the prom. To Freddy's horror, the killer is his overly-possessive mother Kathy, whose crime he took the fall for. Behrad manages to knock her out, undoing her damage in 2004. The Legends reconvene at the reunion, learning Freddy and Tiffany got married while Mick reconnects with an old girlfriend, Ali. Meanwhile, Constantine resorts to desperate measures to stop Astra's Encores by facing her mother's ghost, much to Charlie and Gary's dismay.

Sara leaves Ava in charge of the Legends while she heads to Star City for business. An Encore appears in 1793 France, causing a massacre. The Legends investigate, finding Marie Antoinette, who was encored after her execution. Discovering Marie has magic perfume, the Legends capture her, separating her head from her body. Not understanding how dangerous the perfume is, Zari steals it when Behrad takes her back to 2040 for her own perfume's launch. Behrad, Nate, and Ava go to stop her while Marie's body gets free and steals Mick's Heat Gun. Zari is pushed into a fountain to wash off the perfume and escorted back to the Waverider before she can damage history any further. They return just as Mick and Ray stop Marie's body and lock it in the lab, though Astra recalls her back to Hell. Zari has another flashback of her old life and talks with Ava about life's difficulties, becoming friends. Meanwhile, Constantine is tormented by various ghosts. She reveals that the Loom of Fate is the key and Charlie knows where it is. Charlie reveals she destroyed it, just as Constantine starts coughing up blood.

When he is diagnosed with stage 4 lung cancer, Constantine concludes Astra tampered with his soul coin and forces Ray and Gary to help him find a way to extend his life, but to no avail. Poisoning himself, Constantine goes to Hell and tells Astra that he promised her mother that he would use the Loom of Fate to save them, so she gives him his remaining years back. Meanwhile, the Legends head to 1990s Hong Kong, where Genghis Khan is attempting to start a new empire by using a hell sword and the contemporary Triads to force Prince Charles to hand over control of the city to him. Using her powers to disguise herself as Prince Charles, Charlie manages to steal Khan's sword and kill him with it. Following this, Charlie reveals to her friends that she is actually Clotho of the Fates and that she scattered the Loom of Fate across the multiverse to give everyone free will. Due to the Crisis however, the pieces are now on Earth-Prime and her sisters are out for revenge against her.

Ray plans a romantic dinner for Nora at Constantine's house, planning to propose to her while Nate and Behrad babysit her latest charge, Pippa, on the Waverider. Unfortunately, her father Damien Darhk is encored following Mallus' demise and steals his Gary's time courier to get to 2020. When Constantine blunders in, Nora tries to pass him off as her lover and her friends as her minions. The ruse fails, forcing Nora to reveal the truth, disappointing Damien. After Pippa wishes everyone into the TV show, Mr Parker's Cul-De-Sac, Nora tells Damien that being a fairy godmother helps her with the trauma of being raised by Mallus' cult instead of him. Damien gives his blessing and everyone is released. Ray and Nora have a makeshift wedding, with Damien advising his new son-in-law that Nora cannot live her life to the fullest as a Legend. He discreetly leaves and kills himself with Khan's blade. Meanwhile, Mick learns someone has libeled his books. With Zari's help, he tracks down a girl named Lita, whom he learns is his and Ali's daughter. Not wishing to taint Lita's life with his presence, Mick erases the visit from everyone's minds.

While in 16th century England to retrieve the first piece of the Loom of Fate, the Legends inadvertently inspire William Shakespeare to rewrite Romeo and Juliet as a superhero story just as he was about to write its ending. Even worse, they fail to wipe his mind correctly following a bar fight. Initially, they decide to let the playwright be as they got what they came for. However, Sara refuses to accept this and forces her team to return and convince Shakespeare to write Romeo and Juliet as intended. After his boss withdraws his actors before a performance, Shakespeare becomes despondent until the Legends offer to fill in for them. Following this, Ray and Nora leave the Legends to live their lives together. Meanwhile, Astra attains a special viewing device to spy on Constantine. However, he quickly catches on and uses a spell to knock her out. When she comes to, she realizes what Constantine is really searching for.

Charlie's sister, Atropos, murders her old band soon after she was recruited by the Legends. Sara, Charlie, and Constantine discover that the second piece of the Loom is hidden in the present day on the set of Supernatural. Before they can find it, Atropos attacks them and takes both pieces of the Loom before seemingly killing Sara. After she is inexplicably revived, Sara knocks Atropos into the timestream. Meanwhile, Zari tries to discover why she is experiencing memories of the previous timeline. While communing with her family's spirits inside the wind totem, she finds her past self and they discuss their different lives; reconciling their differences and granting Zari control of the totem once more. As Atropos returns to attack the Waverider, she kills Behrad, but Sara and Charlie take back the Loom pieces and defeat her once more. Elsewhere, Mick wants to improve his relationship with Lita, so he and Ava try to make memorable moments and take photos throughout Lita's life. However, Lita continues to be disappointed and Mick realizes that he needs to be more involved in her life in order to be a good father.

Charlie reveals she gave the last Loom fragment to the Enchantress, who made it extremely difficult to find. Constantine tries using everyone's energy to summon the fragment, but Sara faints; forcing him and Zari to travel to 1918 England, where they discover Constantine's house used to be a boarding house. They check-in, only to find several Encores have beaten them there. After disguising themselves as Jack the Ripper and Cleopatra, they discover Charlie's second sister, Lachesis, sent the Encores for the same purpose as them. Though their deception is discovered, Constantine and Zari successfully destroy the Encores, recover their Hell weapons, and get the Ring from the housekeeper; who unbeknownst to Zari, was the Enchantress. Meanwhile, Ava, Gary, and Mick go to Hell to confront Astra and learn why she sent her Encores, only for Astra to discover that Lachesis and Atropos stole her soul coins to get the Loom for themselves, though they offer to give her Charlie's place. Astra accepts to get Constantine's coin back, but secretly joins the Legends to ensure that her fate is changed for the better.

In an effort to bond with Lita, Mick takes her aboard the Waverider for the weekend. Gary also brings his new emotional support dog, Gary Junior, aboard. Charlie tries to use the Loom of Fate to resurrect Behrad, but fails, causing the ship to lose power. Sara wakes up from her coma, only to discover she has gone blind and gained the ability to see near future visions of people's deaths while touching someone. When the Legends learn that the Loom fragments have gone missing and the Waverider was sabotaged, they immediately accuse Astra. However, after hearing a voice telling her to kill Gary, and Zari finds footage of the crew destroying the ship when Junior was nearby, Sara and the others realize that Junior is to blame. Gary reveals that Junior was a "rescue" from Hell, causing Ava to realize that Junior is actually a hellhound named Marchosias. Constantine sends Marchosias back to Hell and Gary recovers the fragments. Ava takes Sara to the medbay to cure her blindness, but Gideon is unable to find anything wrong with her.

The Legends travel to Hudson University, Nate's alma mater, to enter a contest held by the Greek god Dionysus, where the winner will receive an enchanted chalice that will make its drinkers immortal for a day. Sara hopes that by achieving immortality, the Legends will be able to help Charlie use the Loom. While forming a sorority to ensure the Legends' eligibility in the contest, Nate falls under Dionysus' influence as he intends to discourage their efforts and "keep the party going," recalling how the Fates used the Loom to suppress free will. After sabotaging one of Dionysus' parties and winning a game of beer pong using her newfound cognitive ability, Sara gets the chalice and suggests that they all drink from it, to which everyone but Zari agrees. However, Astra is confronted by Lachesis, who has come to collect a favor from her.

Astra is forced to leave the Legends behind at Constantine's house and hijack the Waverider so the Fates can use the Loom in exchange for them resurrecting her mother, but Lachesis talks her out of it. Gary, who got stuck onboard the timeship, works with a hallucination of Gideon to keep the Loom fragments away from the Fates. He persuades Astra not to betray the Legends, but before she can get them back, Atropos kills her for betraying the Fates. Meanwhile, the Legends attempt to head to an old Time Bureau safe house in London to get a time courier, but Atropos pursues them and creates a zombie apocalypse in England. The team's immortality ends before they can use the courier and they sacrifice themselves to allow Charlie to escape. She is able to get back onto the Waverider and get the fragments from Gary, but Atropos kills him. With nowhere left to run and no other options, Charlie gives the fragments to her sisters and agrees to help them use the Loom.

In a dystopian world controlled by the Fates, Mona, Gary, and the rest of the populace tune into television shows made by Clotho Productions, starring the Legends. While in the sitcom Ultimate Buds, Zari is possessed by her previous timeline self, who realizes their world is not real. Mona and Gary go to Clotho Productions and find their friends trapped in an algorithm and restore their memories, including the previous Zari and Behrad. Charlie reveals she crafted the algorithm for the Legends to live in to keep them safe. After Charlie uses Mr. Parker from Mr. Parker's Cul-de-sac to return the Legends to their shows, they escape by getting their shows cancelled, finding themselves on an empty TV set. Charlie offers to restore the shows and allow both versions of Zari to exist separately to try and control them, but the Legends choose free will and leave the set. Charlie tells Mona and Gary she can no longer protect her friends from her sisters because of their decision.

Infiltrating the Fates' temple, Sara kills Atropos by throwing her into the Loom of Fate, destroying it. As a result, Sara loses her powers and regains her sight. Traveling four months into the future, the Legends find Lachesis rebuilt the Loom as a smartwatch app and imprisoned Charlie in The Museum of Bad Ideas, who has been convinced that everything wrong with humanity is her fault. Freeing her and taking her back to the ship, the Legends find that the Loom really is destroyed and Lachesis is using Gideon as a cover. Lita helps Charlie see good can come from chaos and inspires her to join the Legends in shutting down Lachesis' app and killing the final Encores at the museum. Realizing Lachesis is human without the Loom, Charlie forgives her and tells her to live the one life she has. The previous timeline's Zari realizes her presence is slowly killing Behrad, so she returns to the totem. Returning to 1970s London and her band, Charlie also leaves the team. Astra begins her second chance at life by moving in with Constantine and giving him his soul coin back. Unbeknownst to the team, Sara is abducted by aliens.

After a night of partying in 1977 London following the defeat of Lachesis, Ava Sharpe realizes that Sara Lance is missing, and learns from David Bowie that she was going to propose but was abducted by aliens. Ava is consoled by Nate Heywood and contacts the D.E.O., unaware that it was destroyed.[a] John Constantine returns to his house with Zari Tarazi and Astra Logue and fails to find Sara using magic, but discovers a human chrysalis in Gary Green's room and Image Inducer glasses that can transform its wearer. Behrad Tarazi reads about a girl who could communicate with aliens named Esperenza Cruz, so Ava sends him and Mick Rory to recruit her, but Mick ultimately kidnaps her. On a spaceship, Sara escapes from her containment pod and frees Spartacus, only for him to be eaten by Kayla, the boss of the ship. Sara attacks one of the alien captors, and discovers that it is Gary, who was initially sent to Earth to acquire the most "quintessential" human (Sara) but out of a new-found love for humanity, he agrees to help her escape. Sara knocks Kayla (also Gary's fiancèe) out of the ship by releasing other containment pods into a wormhole leading to Earth's Temporal Zone, but fail to reach the wormhole themselves and fall towards another planet.

The Legends track an alien to 1955 San Bernardino, California, to before the death of the entire town. At Big Bang Burger, a popular burger joint run by Bert Beeman, Mick learns from a police radio about attacks at places with meat. Nate, Zari, and Behrad get jobs and Zari asks Behrad if she can use the Air Totem, but he says the totem chose him. The restaurant's secret sauce causes people to go berserk and is the recipe of Bert's wife Rhonda who wanted her family to outdo those two brothers. Spooner tries to convince Ava that Sara is gone and that pursuing aliens will lead to more loss. While questioning Rhonda, Ava finds a cocoon in her attic and learns that the sauce is pus dripping from the cocoon, which hatches a moth-like alien that eats Rhonda and Bert. Spooner shoots it dead. In the Air Totem, Zari Tomaz grows sick of the Tarazis' bickering and splits the totem into two for both siblings to use. Waitress Sandy Sledge takes over Big Bang Burger and turns it into the first Big Belly Burger. Sara and Gary find Amelia Earhart on an alien planet, but she transforms into an alien and attacks them. They escape and are stopped by soldiers.

The Legends travel to 2045 Hollywood to stop an alien named Lord Knoxicrillion from killing DJ S'More Money, Zari's ex-boyfriend, who is judging a competition called "Da Throne," but S'More Money believes them to be a performer and promotes them to the finals. To stop Knoxicrillion from invading, the Legends convince them that winning "Da Throne" will make them king of Earth. Zari tells her mother during a visit that she doesn't think her relationship with Constantine will last, but he overhears and later walks out on her during an interview. Mick is upset with Sara's disappearance and his daughter Lita's ignorance, but is consoled by Ava and Spooner. Constantine and Zari reconcile and outperform Knoxicrillion, who reveals himself as a small alien piloting a suit, Mick kills them and begins a search for Kayla, who can lead them to Sara. Sara is wounded after Earhart's attack, so Gary eats their pursuers only to learn that they're Ava clones. Sara follows one back to its base, where she meets a man who has been "waiting a long time for her."

Kayla lands in 1962 Cuba, and Mick leads a charge to seize her only to find a missile instead, not knowing that it's the Cuban Missile Crisis. While infiltrating a Cuban base, Ava kidnaps Kayla and Behrad is mistaken for Che Guevara. Nate and Zari travel to Washington, D.C. and infiltrate John F. Kennedy's inner circle hoping to de-escalate tensions. Mick and Spooner are forced to cede the missile, which Fidel Castro orders to be fired at D.C. (despite Behrad's intervention) after being attacked by Kayla, who he assumes to be an American mutant. Zari sabotages a retaliation order from General Kilgore, and Nate stops JFK from launching a counterstrike. Mick and Spooner request Kayla's help in finding Sara in exchange for returning her home, which she accepts. The missile lands in D.C., but doesn't detonate. Nate sees Zari for who she is now and not as a reminder of the Zari he lost. Kayla transforms into a human through an Image Inducer ring and she and Mick leave on the Waverider to find Sara while the rest of the Legends travel to Constantine's house.

At Constantine’s manor, Astra struggles with everyday chores and is ignored by Constantine. Astra finds occultist Aleister Crowley trapped in a painting. He teaches her magic and about the Fountain of Imperium, an alien magic source. During an argument with Constantine, Astra gives Crowley control of his body. When the Legends arrive at the manor, Astra transforms them into household objects. However, Crowley betrays her and transforms everyone into cartoon characters. Astra uses a spell created by her mother which traps Crowley and returns everyone to normal, but also removes all magical abilities, prompting Constantine and Astra to begin anew. Meanwhile, Sara meets Bishop, her kidnapper and creator of all Ava clones. After healing Sara of Zaguron poison, Bishop claims that human greed doomed Earth and intends to restart humanity using alien DNA. Sara works with an Ava clone to escape, but she betrays her and leads Bishop to her ship. Sara kills Bishop, but she is knocked out only to meet him again back at his lair.

Gideon, reinstalled in Constantine's manor, alerts the Legends to a massacre done by the Amelia Earhart alien, who used Sara Lance as an alias and arrived alone in the Waverider. After retrieving her from a mental institution in 1956 Rye, New York, Astra reads her memories and finds that she is the real Amelia who was abducted and fused with the DNA of a Zaguron. It overtakes Amelia and claims that it killed Sara, and that there is an alien inside Spooner before being killed by Ava. Constantine and Astra cover up the loss of his abilities to Zari. Meanwhile, Mick is captured on Bishop's planet by Ava clones, and Bishop tries to kill him by exposing him to the toxic atmosphere, despite endangering the Ava clones. Gary rescues a dying Ava clone while Mick escapes and shares an oxygen mask with Kayla, and the two have sex afterward. Bishop reveals himself as a clone to Sara. Sara attacks Bishop after learning that Mick may have died, but he reveals that she too is a clone and unveils the real Sara's dead body.

While grieving Sara, the Legends (without Ava) follow Behrad back to 1977 London to stop Sara’s abduction. During several failed attempts, the past Ava finds and orders them to return to the future, Zari deduces that Constantine lost his magic, Spooner discusses her fears with the past Sara, and a future Nate arrives stating that their plans fail before being erased. Bishop reveals that Sara died from Zaguron poison, which has no cure, and has her incinerated. He then creates a new Sara clone and reveals that she is the first to be fused with the DNA of an alien. Mick kills Bishop, unknowingly allowing him to upload his consciousness, forcing Sara to abandon a plan to create a fully-human clone. Gary detonates Bishop's base, and the Ava clones choose to stay behind. When attacked by Zagurons, Kayla sacrifices herself to allow Sara, Mick, and Gary to escape from the planet. They reunite with the Legends and Sara proposes to Ava, who happily accepts.

Sara reveals her regenerating alien-human hybrid clone status to Ava and asks her to keep quiet. The Legends travel to 1891 Fist City, Oklahoma Territory, where they find the town's residents to be abnormally kind and inviting. They later learn that Levi Stapleton, the sheriff, keeps the town compliant using an alien worm that devours angry people, which Gary identifies as a Haverick. Sara challenges Stapleton to a duel and is shot, but regenerates, revealing her secret. Stapleton loses the whistle controlling the Haverick and is devoured. Astra and Spooner meet Bass Reeves (who Sara later mistakes for John Diggle), who had been maligned by Stapleton. The Legends' bickering summons the Haverack, but it is destroyed by Astra and Spooner. Afterwards, Reeves cleans up Fist City, Gary tells Constantine of a map to the Fountain of Imperium (which is on Earth), and Behrad gives his and Zari's totem to Nate so he can visit the other Zari.

On Behrad's birthday, the Legends track an alien to 2023 Vancouver, British Columbia, where Behrad's favorite sitcom "Bud Stuy" is being recorded. Spooner shoots the pod out of the sky, knocking it onto the set where a Gusarax escapes, altering the timeline. The director, Kamran Saaed, bonds with the Gusarax and opts to incorporate aliens into the show, upsetting his brother and the lead, Imran, who later quits. The new timeline erases Behrad's memories of the Legends and both his and Zari's totems, and transforms him into a cold businessman intent on marketing the Gusarax. However, Zari and Astra get Imran and Kamran to reconcile while the Gusarax bonds with Nate instead, restoring the timeline. Meanwhile, Mick is angered to find that the 2023 Lita is pregnant and leaves to kill her boyfriend Niko. He calms down when he realizes that Lita and Niko will be loving parents. Afterwards, the Legends celebrate Behrad's birthday. Zari safely trades places with Zari Tomaz and Gary reveals that Kayla laid eggs in Mick's ear.

Constantine acquires a map to the fountain and a magic potion from a vampire named Noelle. He recruits Spooner and travels to 1939 Albacete, Spain, in search of a man known as El Gato, who they believe used the fountain's magic to survive several assassination attempts. They meet with him and find that his mute nephew, Fernando, wields the fountain's magic and has been using it to resurrect his uncle. Fernando leads Constantine and Spooner to the fountain, but find that it's dried up. When attacked by Captain Noriega, an ally of Adolf Hitler, Constantine resorts to using the magic potion to kill him. Afterwards, Constantine trades Crowley's soul to Noelle for more potions, and brainwashes Spooner when she threatens to tell Zari. Meanwhile, the Legends struggle with the Gusarax's rapid aging, and are forced to eject him from the Waverider when he becomes too hostile. With Lita's help, Mick grows to accept his pregnancy.

Sara, Mick, Astra, and Spooner find a puzzle box inside the last alien pod in 2021 Kansas City, Kansas, which transports them to Galaxy Lanes, a bowling alley in space. The champions, The Pin Killers, miniaturize Earth into a bowling ball, stranding Nate and Zari, who were camping in Alaska. The owner, Buddy, explains that if the Legends defeat the Pin Killers, Earth will be restored. If they lose, Earth will remain that way and the Legends will disintegrate. While searching for help, Zari wonders if her relationship with Nate is worth having if they can stand to be apart. Meanwhile, Gary tries to distract Ava by helping her find the perfect wedding dress as Constantine uses a spell to bring the Waverider to Galaxy Lanes. Sara struggles to get her team to cooperate, but she remains optimistic and helps them unite. On Earth, Zari shoots at Mike the Strike's finger, disrupting a roll, allowing Sara's team to defeat the Pin Killers. Afterwards, Nate reassures Zari of his desire to be with her, Sara restores Earth, and the Legends reunite at the bowling alley. When Buddy notices Constantine, he worries that his power could be the death of him.

Since Constantine's magic damaged the Waverider's jump drive, the Legends must take a three-week journey back to Earth. Zari swaps out with Zari Tarazi, and Constantine continues juicing after suffering from withdrawal. Constantine transports everyone (except Gary and Mick) inside a board game called "Beast Slayer". The game becomes horrifyingly realistic, so Sara tries to end it by revealing herself as the beast only to be killed by a new one. Constantine learns that the new beast is a "dark side" of himself who states that the magic is in control of him before being stabbed by Zari, ending the game. Concurrently, Kayla, who survived her ordeal, arrives on the Waverider and fixes the jump drive, but later attacks Gary and Mick out of an allegiance to someone who helped her escape. Mick reveals his pregnancy, but she knocks him out. Kayla's severed tentacle begins creating a new body and strangles Gary. Afterwards, Zari admits her love for Constantine to Behrad despite his warnings, but later finds Constantine's stab wound and realizes he was the beast. Sara follows a voice on the Waverider and finds someone unexpected.

Sara finds and captures Bishop, who explains that Kayla was only able to download 94% of Bishop's original genome due to Sara's actions. Ava interrogates him, but he swears that he's turned over a new leaf. Ava pretends to be vulnerable by allowing Bishop to help plan their wedding, but she begins to sympathize with him. As Mick goes into labor, Sara and Ava discover that the other 6% of Bishop's genome belongs to Sara, allowing Bishop to override Gideon and defeat Sara. He delivers 48 eggs through Mick's nose before willfully returning to imprisonment. Meanwhile, Zari confronts Constantine, who is still being taunted by his dark side. Astra restores Spooner's memories, and Zari steals a potion from Constantine, which Astra identifies as a Scarlett Lady, blood from Hell. Constantine confronts Zari, but chooses to throw out the potions and the two reconcile. Afterwards, Sara finds that Bishop aided in Mick's delivery in order to steal his comms. He contacts Constantine, who has been overtaken by his dark side despite his actions, with an offer to find a way to officially restore his magic.

Constantine and Bishop disable Gideon and steal the Waverider to search for the Fountain of Imperium in 1925 Texas. Spooner and Astra stow away and defend Spooner's mother Gloria from having her land taken. Alongside Constantine, they meet a younger Esperanza. Constantine knocks everyone out and reveals to Spooner that Gloria will be killed while defending her land and that Esperanza will flee to the woods where the Fountain will transport her to the future. That night, Bishop and Constantine activate the Fountain. Spooner reveals her identity to Gloria and protects her and her land while Astra sends young Esperanza to the future. Meanwhile, the rest of the Legends lure Kayla back to Earth using Mick's eggs in order to use her ship and rescue the eggs from the Waverider, but they discover that Bishop has set a trap and Mick gets caught in an explosion while attempting to save one of the eggs. Constantine links to the Fountain and attempts to betray Bishop, but he anticipated this and poisons him, weakening the Fountain and knocking out Spooner. Bishop reveals the Fountain was an alien gift that would safeguard Earth from invasions and escapes. Constantine is enveloped by the dying Imperium at Astra's and Zari's side.

Bishop steals Kayla's ship and Mick saves the last egg. With the Fountain weakened, Zaguron scouts are able to invade but are killed by Sara, Ava, and Nate. Zari and Astra inform the Legends of Constantine's death and bring back a mushroom, which Behrad hypothesizes to be Constantine. Sara eats the mushroom to connect with him and is reminded that everyone is connected. The Legends kidnap a young Bishop from 2212 Vancouver and have him create an antidote that awakens Spooner, but the Fountain still isn't restored, allowing Zaguron pods to land on Earth. Fearing it may be their last day, Spooner begs her mother to flee while Sara and Ava move up their wedding. Bishop arrives on Kayla's ship and opens the pods, but the Legends' connection revives the Fountain and allows them to use each other's special abilities to kill the Zagurons. Mick's eggs hatch and devour Bishop. Afterwards, Mick plans to leave with Kayla and bids farewell to Sara. Zari mourns Constantine when he suddenly arrives from Hell, damned once more. He gives Zari a key and bids her farewell, wanting to walk his path alone. After returning young Bishop to 2212, a second Waverider appears and destroys the first before disappearing, stranding the Legends.

A second Waverider destroys the original, stranding the Legends in 1925 Odessa, Texas. They pass the alien invasion off as a circus act, but Esperanza "Spooner" Cruz stops this in order to take pressure off of her mother Gloria. Astra Logue uses a spell to find a safe and learns that it was given to the sheriff, so Nate Heywood retrieves it by impersonating J. Edgar Hoover, but they find that Mick Rory took the safe's Time Courier for a beer run. Astra fails to reform the Waverider causing an explosion that alerts the real Hoover. Using John Constantine's key, they hide in a Hell pocket dimension with a duplicate of his mansion. Ava Sharpe reads about Gwyn Davies, the forefather of time travel, so Sara Lance suggests they travel to him in New York City while robbing banks to lure Hoover away. She and Ava form The Bullet Blondes and leave with Nate, Gary Green, and Behrad Tarazi while Zari Tarazi stays in the mansion. Nate accidentally kills Hoover in self-defense, so Gary eats the body. Astra inadvertently creates a human Gideon.

Sara's group catches a train to New York. Nate impersonates Hoover using a potion made by Gary while Sara and Ava return to the mansion. Ava helps Zari cope with her breakup and the two focus on identifying who destroyed the Waverider. As Nate struggles to come to terms with killing Hoover, the train is stopped by FBI agents intent on stopping a kidnapping. While pretending to coerce a Russian man into giving information, Nate realizes the train's destination has changed and that the FBI agents are fakes sent by Al Capone to kidnap him. Gary's potion wears off, so Nate's captors can't deliver him; this allows him to accept Hoover's death. The Bullet Blondes pay off Capone's men, but are caught by an aggressive Hoover robot and he self-destructs, suggesting that robots destroyed the Waverider. Back in Texas, Gideon acts erratically and is unable to speak. Spooner restores her speech and she states that they must reach Davies' time travel experiment in two weeks before the Legends do, or else they will die.

Gideon struggles with making decisions and collapses. Astra and Spooner enter her mind and meet a memory of Jefferson "Jax" Jackson defending her subconsciousness. Astra and Spooner help Gideon recover lost memories of the Legends, which included Ray Palmer, Carter Hall, Leonard Snart, Martin Stein, Rip Hunter, Nora Darhk, and Zari Tomaz. Along the way, Gideon is attacked by a virus of herself who doesn't want to be human. It corrupts her memories, forces her to re-experience the deaths of several Legends, and reveals that Rip had reprogrammed her to protect them against her will. Jax, Astra, and Spooner uncorrupt the memories and show Gideon happier ones, convincing her to embrace her humanity and take control of the virus. She is comforted by all of the Legends and wakes up. In 2213 Vancouver, British Columbia, the younger Bishop has dreams of his future self and the Legends from the alien invasion in 1925. He finds a copy of Gideon that he downloaded and resets her memories, intending to use her against the Legends.

Sara's group hides from another Hoover robot in a Chicago speakeasy. They raise money by selling the mansion's infinite drinks at the bar and give the rest of the sales to Eddie the bartender, but this violates Eddie's deal with his gangster landlord Ross Bottoni, so he takes the club back. Zari raises money for Eddie by holding a party in the mansion with a performance by The Bullet Blondes. Gary notices that Nate puts himself in doomed relationships so that he won't have to commit, motivating Nate to talk to Tomaz. Meanwhile, Spooner's group sneaks onto a train to Chicago with the help of a jazz band called the Masqueradies and their leader Maude Beaumont. Bottoni, her abusive boyfriend, forces her to sing at his club, but Spooner's group convinces her to cut ties with him. The Hoover robot finds Zari's party, but the Legends capture him. Spooner's group tries to catch up to Sara's to no avail as Gary has already boarded a train to New York with the rest of the Legends in the mansion. Zari swaps out with Tomaz in order to interrogate the Hoover robot.

Sara's group arrives in New York and discovers that Davies' time travel machine is missing one component. Gary finds it, but it is confiscated by Thomas Edison, who terminates Davies and takes his plans. Nate suggests Zari move into the mansion where she can coexist, but she wants them to live in the totem. They learn that the Hoover robot was sent to replace the original and eliminate the Legends. Behrad activates the machine, but this erases Ava and Gary. Davies agrees to help Sara if she helps him get his loved one back. Zari reprograms Hoover to steal Davies' plans back, but he explodes, giving Edison a heart attack, so the second Waverider delivers new robots for both of them. Davies activates the machine himself, restoring Ava and Gary. Astra's group nearly makes it to New York with the help of Erwin George Baker, but the car is stolen, so Astra short-circuits all of New York to stop the machine. They reunite with Sara's group and successfully time travel with a chip from the Hoover robot, but land in an unknown place and time.

In 2214 Vancouver, Bishop builds his own Waverider with schematics from his Gideon. He and his Ava clone assistant become Time Masters, travel to 1925, destroy the Legends' Waverider (against A.I. Gideon's advice), and correct the resulting aberrations by using the Ava clone technology to build robot replacements. A.I. Gideon ejects the Ava clone into the timestream and creates a Bishop robot to live out his life so he can continue chasing the Legends, though he becomes reluctant after discovering his future story. Meanwhile, Davies' time machine breaks, so Astra and Spooner help Sara and Ava express their frustrations. Nate decides to move into the totem, while Gary and Gideon unexpectedly bond over their experiences as humans. Davies tells Zari that he built the time machine to rescue his fallen lover Alun and his allies from World War I. Behrad learns they're in 1986 Chernobyl on the day of the meltdown. Davies broadcasts an evacuation warning, which alerts Evil Gideon. The Legends repair the machine and escape, but Bishop escapes from his Gideon and enters the machine at the last second.

The Legends arrive in 1943 with Bishop and lock him in the mansion. The time machine breaks again, so they smuggle components out of a nearby airplane factory in order to repair it. Astra is taunted by the racist boss, Mr. Staples, and accidentally freezes him. She takes over and integrates the factories, prompting most of the white Rosies to quit, so she helps the remaining Rosies finish building the plane. Eleanor Roosevelt comes to the factory and applauds their work, convincing a thawed Mr. Staples to allow them to keep their jobs. Meanwhile, Zari swaps out with Tarazi, and Astra inspires Behrad to stop Bishop from mooching while he teaches Nate taarof in order to appease the ancestors in the totem. Bishop apologizes with a device that will allow Gideon to control the time machine. Eleanor asks Congress to integrate all factories (two years early), but this alerts A.I. Gideon, who sends soldiers to attack. Bishop kills two soldiers and sacrifices himself to allow the Legends to escape. The soldiers are revealed to be robot clones of the Legends; the two dead ones are revealed to be the Zari and Astra robots.

Ava's robot clone Dr. Sharpe miraculously revives the Zari and Astra robots. The robot Legends, believing they’re the real ones, correct aberrations in 1986 Pripyat, Ukraine by killing soldiers who were supposed to die in the Chernobyl meltdown. They manipulate General Kalashnik into framing Davies' broadcast as a false alarm. Robot Sara is accidentally shot and is operated on by Sharpe, where she notices a robot part being pulled out of her. She steals CPUs of the team's medical records and brings them to their Zari, who learns that they are the true androids and are being controlled by their Gideon and that their CPUs are transferred to new robot bodies upon death. Robot Sara is ordered to assassinate Dr. Irina Petrov, the new sole survivor of Chernobyl, and fakes her death. She then threatens Sharpe, who confirms everything, but A.I. Gideon promises to make them better than the original Legends. Robot Nate replaces Robot Sara as captain while she is reprogrammed and kills Petrov.

The Legends arrive in the manor, and Gwyn accidentally allows a reality TV show crew to manifest inside. They are the Cursed Crew, who seek human drama and can amplify emotions to create more. Astra goes to Lowest Common Demoninator Productions to shut the show and is followed by Behrad, but the boss Harris Ledes threatens his life to keep the show running. Under the show's influence, Sara shirks strategizing with Ava to plan a vacation, Nate and Zari argue about his relationship with Tomaz, Spooner becomes a nudist, Gwyn resolves to rescue Franz Ferdinand to stop World War I, and Gideon surpasses her emotions and dumps Gary after the other Legends react unfavorably to their relationship. She instigates more fighting, leading Gary to eat Bishop's time device. Behrad arrives and admits his emotional vulnerability, interrupting the drama long enough to where the Cursed Crew is able to leave. As everyone reconciles, Astra and Behrad admit their mutual feelings. Gideon suggests they travel to 1914 Sarajevo to stop the assassination of Archduke Ferdinand, much to the Legends’ surprise.

Since Ferdinand's death was a "fixed point" in history, an aberration there would alert A.I. Gideon. In Sarajevo, a bartender identifies the Legends as time travelers and brings them to an otherworldly bar where he explains that anyone who tries to change a fixed point is "killed by time." Patrons who want to try are expected to wait in a queue and Sara attempts numerous times. Since Astra and Behrad are spending time together, Zari and Spooner connect and Spooner discovers her asexuality. In the mansion, Ava realizes that if Gwyn rescues Alun, he won't invent time travel. Gwyn thinks he does not deserve to be with Alun due to being a man of faith and a homosexual. The Legends realize that someone is freezing time and killing the rescuers. Using an anti-time manipulator built from the time machine's parts, Sara finds Eobard Thawne. He states that after his defeat, the Time Wraiths removed his speed, re-educated him, and had him defend the fixed point. However, he agrees to delay the archduke's assassination by 40 minutes. In exchange, Sara agrees to take up Thawne's duty if he dies. After Thawne resumes time, the Waverider lands near the Legends.

The Waverider drops off Robot Sara, Nate, and Behrad who massacre Thawne and the bar patrons. Robot Behrad shoots Ava, but is shut down by Astra. Sara tries to reason with Robot Nate, but to no avail. Gwyn uses his military experience to devise a plan. As the Legends create more aberrations to lure the robots back, Behrad impersonates his clone and boards the Waverider. He tricks Robot Astra and Dr. Sharpe into entering the mansion where Gary knocks them into Hell. Robot Zari follows and is broken by Zari, who impersonates her and disables A.I. Gideon. Spooner tricks Robot Gary into eating Robot Spooner and he explodes. Astra initially refuses to let Gideon participate due to the maternal bond she feels with her, but she eventually allows Gideon to trick Robot Sara into removing her CPU. Nate tricks his doppelgänger into taking up Thawne's duty. Gideon returns to the mansion to retrieve Gary and Ava, but she is stabbed by a badly-burned Robot Astra who shuts down shortly after.

In order to mend Gideon from her injury, the Legends reactivate A.I. Gideon and remind her of Protocol 276, which prohibits her from harming herself. Gideon recovers and A.I. Gideon agrees to spare the Legends if they retire and shows them glimpses of their futures as a sign of good faith. The Legends initially distrust this and try to destroy A.I. Gideon, so Gideon agrees to become a Time Master and watch over her. The Legends contractually agree to retire and Astra duplicates the mansion key so that they can all visit one another. Gideon rescues Alun, and he and Gwyn admit their feelings for one another. The Legends go their separate ways, while Gary chooses to stay with Gideon. Gideon later admits that Alun's death was a fixed point and she created a robot clone of him. Gwyn discovers this and plots to rescue the real Alun. A.I. Gideon tricks Gary into entering the airlock and ejects him into the timestream. Afterward, she falsely informs Gideon that it was his decision.

Gary lands in 30,000 B.C., but returns to the manor. The Legends learn that Gwyn died at the fixed point in 1916 Mametz Wood, France. Gary deduces that Sara is pregnant (due to her alien biology) and her regenerative abilities transfer to the baby. The Legends travel to before Gwyn's death, but are intercepted by Gideon who tells them to leave. Astra and Spooner convince her to turn against A.I. Gideon, who uploads herself into a clone body. Gideon disables the Waverider's cloaking, causing her clone to become an anomaly. She self-destructs in the Temporal Zone, but Astra shields her group and reforms the Waverider. The others meet with Mike, the Fixer. Gwyn states that anyone attempting to change the battle would be erased in a time paradox making Mike feel useless. He destroys Gwyn's machine and steals the Waverider to talk to his superiors. Nate rescues Alun, but is permanently depowered by mustard gas. Afterward, Sara reveals her pregnancy to Ava, while Nate retires to the Wind Totem. Mike returns with the Waverider, but he and the Legends are arrested by his superiors.

In October 1989, a meteor shower hits Smallville and with it arrives a little boy. The child is adopted by Martha and Jonathan Kent, and named Clark. Twelve years later, Clark struggles to understand his identity. After Clark saves Lex Luthor's life after Lex drives his Porsche off a bridge, the two become fast friends. After sharing an intimate moment with Lana Lang, Clark is forced into a school hazing ritual led by Lana's jealous boyfriend Whitney. Meanwhile, Jeremy Creek (Adrian Glynn), a teenage boy who was left in a coma after the first meteor shower, wakes up and sets out to get revenge on those that hurt him. Afterward, he prepares to do the same to the rest of the Smallville High students, but Clark arrives in time to stop him.

Greg Arkin (Chad Donella) gets into a car accident with his meteor rock-enhanced insects, which escape from their containers and begin stinging him. The resulting attack transforms him into a half man/half insect creature. Rapidly going through a metamorphosis, Greg kidnaps Lana so he can mate with her. After talking with Whitney, Clark realizes where Greg has taken Lana and leaves to rescue her. During the fight, Greg accidentally crushes himself under some mechanical equipment, resulting in a mass of insects flooding out from underneath. Before Clark can return to Lana, Whitney arrives and receives credit for her rescue.

A meteor rock infused sauna endows Coach Arnold (Dan Lauria) with pyrokinesis. After several football players are caught cheating, Chloe discovers that Coach Arnold assisted the players when they cheated. Coach Arnold asks Clark to join the football team, and Clark agrees against his father's wishes. Clark confronts Coach Arnold before his first game, after Arnold attempted to kill Chloe and another football player for exposing the truth about the cheating. The coach's fury gets the better of him as he engulfs himself in flames while battling Clark.

Clark begins to develop X-ray vision when he is thrown through a window by Lex Luthor, who has just robbed the local bank. Clark accidentally x-rays Lex's body and discovers a green glow around his skeleton as Lex is running away. When it turns out someone was impersonating him, Lex is cleared of all charges. After gaining control over his X-ray vision, Clark discovers that Tina Greer (Lizzy Caplan), a young woman infected with meteor rock radiation, can morph into anyone she wants. He also learns that she robbed the bank when he X-rays her locker and sees the money from the bank. After a brief battle, Clark knocks Tina unconscious so the authorities can arrest her. Meanwhile, Lex hires Roger Nixon (Tom O'Brien), an Inquisitor reporter, to find out how he survived driving his Porsche off a bridge.

During a party at Crater Lake, Sean Kelvin (Michael Coristine) falls into the frozen lake and emerges with an insatiable hunger for heat, thanks to the meteor rocks on the lake bottom. In an effort to stay warm, Sean sucks the heat from anyone he can. Sean goes after Chloe, but Clark is there to stop him. Clark finds Sean, who is headed to Luthor Mansion, but is left frozen when Sean sucks the heat from his body. Clark's body reheats itself, and he arrives at the mansion just as Sean is about to attack Martha, who came with Jonathan to discuss their financial troubles with Lex. During the fight, Clark throws Sean into a lake, which immediately freezes with Sean inside.

Clark meets an elderly, blind woman, named Cassandra Carver (Jackie Burroughs), who receives precognitive visions by touching someone. When she touches Clark both of them see Clark surrounded by the tombstones of everyone he loves. Lex visits Cassandra, after listening to Clark, and her vision of him entails blood raining from the sky. Harry Bollston (George Murdock), an elderly man at a nursing home, falls into a meteor rock filled pond, which reverses the aging process. Harry (Eric Christian Olsen) uses his new youth to get revenge on the children of the jury members that put him away for murder decades earlier, one of whom was Jonathan's father. Clark stops Harry before he can kill Martha, who happened to be home when Harry came looking for Jonathan.

Jodi Melville (Amy Adams) is tired of being overweight, so she creates her own diet, which consists of meteor rock-infected vegetables. The new diet causes her to shed weight faster than she can handle, which forces her to suck human fat to satisfy her hunger. When Pete arrives to pick her up for Lana's birthday party, her hunger gets the better of her, and she tries to feast on Pete. Chloe and Clark discover the truth about Jodi's weight loss, and Clark rushes to her house to save Pete. Clark stops Jodi from killing Pete, and gets her the help she needs to maintain a healthy weight; in the process, however, Clark misses Lana's birthday party, but makes it up to her by giving her his present: a makeshift drive-in theater complete with the classic Bugs Bunny cartoon High Diving Hare. Meanwhile, Lex becomes interested in the effects of meteor rocks, and funds a study on the green meteor fragments.

LuthorCorp is experimenting with meteor rocks, and overexposure to the rocks has caused employee Earl Jenkins (Tony Todd) to develop violent seizures. During a field trip to the local LuthorCorp plant, Clark and his classmates are taken hostage by Earl, who wants into “Level 3” (a secret testing facility at the plant) so he can find a cure for himself. Clark discovers “Level 3” just as Lex trades himself for the hostages. Clark reveals “Level 3” to Earl and Lex, but Earl's seizures put all three in danger. Clark manages to keep them all alive, and Lex makes a public statement that LuthorCorp will find a cure for Earl's condition.

Sam Phelan (Cameron Dye), a corrupt Metropolis cop, witnesses Clark using his abilities and decides to blackmail Clark. When Clark double crosses him, Phelan frames Jonathan for murder, and forces Clark to help him steal a priceless Alexander the Great chest plate. Double crossing him again, Clark alerts the security to the heist. Phelan is gunned down after trying to shoot his way out of trouble, and the charges are dropped against Jonathan when Lex's lawyers arrive. Lex and an old flame, Victoria Hardwick (Kelly Brook), plot to take over their parents' corporations.

Amy Palmer (Azura Skye) is obsessed with Lex. After discovering that Lex's roses release an invisibility fluid, someone attempts to make sure that Lex knows Victoria is wrong for him. Victoria is forced out of the house after almost being killed by an invisible assailant. Amy is blamed for the attack when a watch Lex's mother gave him turns up in her drawer, but it is her brother Jeff (Kett Turton) who is the attacker. Clark confronts Jeff in Lex's manor, and using some paint, keeps Jeff visible long enough to be arrested.

Bob Rickman (Rick Peters) has the ability to bend others to his will, because of an incident with the meteor rocks years earlier. Rickman plans to put a new pesticide plant in Smallville, and he needs the Kent farm to do it. Using his ability, Rickman convinces Jonathan to sell the farm. Clark seeks out Kyle Tippet (Gregory Sporleder) for assistance, after learning that Kyle was with Rickman during the meteor shower. Rickman uses his ability to convince Lex to kill both Clark and Kyle. While Clark is battling Lex, Kyle, who has more control over the ability, forces Rickman to take his own life.

During a class field trip, lightning strikes Clark and classmate Eric Summers (Shawn Ashmore) while Eric is holding a piece of meteor rock. Clark's powers are transferred to Eric, allowing Clark to finally live a normal life. Eric initially uses the powers for good, but soon begins abusing them. Clark decides to sacrifice the chance at a normal life so that Eric does not hurt anyone. Hoping Eric took his weakness along with his strength, Clark confronts Eric at an electrical generator, and uses the electricity, along with a meteor rock, to get his powers back. Meanwhile, Lex double crosses Victoria, who was planning to do the same to him, and has her father's company buy up a worthless research lab. The result allows LuthorCorp to buy the Hardwick company.

Three ex-jocks are using meteor rock-saturated tattoos to give themselves the ability to pass through solid objects. Using their ability, they begin robbing banks. Clark has a confrontation with the thieves and is unable to stop them because of his weakness to the meteor rocks. The thieves decide to recruit Whitney, who has recently begun hanging out with them after losing his football scholarship, but he has second thoughts. Clark helps Whitney and Lex, who is now being blackmailed, fight the thieves. With their powers growing weak from overuse of the serum, Clark is able to subdue them.

Lex's past comes back to haunt him, when Jude Royce (Corin Nemec), a man presumed to be dead, resurfaces after three years and kidnaps Lex. Jude tortures Lex in an attempt to get him to reveal the truth about the cover up of his death. Jude's ex-fiancée's brother is revealed to be the true orchestrater, having found someone who resembles Jude to assist him in his scheme. Angered over his sister's suicide, which he believes is Lex's fault, he wants Lex to pay for her death. Clark saves Lex, but he begins to worry about Lex's past. During a class project, Chloe discovers inconsistencies in Clark's adoption, and it puts strain on their friendship.

Dr. Steven Hamilton (Joe Morton) uses meteor rocks to resurrect a toxic flower, Nicodemus, which has been extinct for 100 years. If someone is sprayed by the flower's toxic mist, they lose all of their inhibitions, acting like they are intoxicated. Jonathan, Lana and Pete are all infected with the flower's toxins, and begin to act out of character. Clark prevents them all from harming themselves or someone else. After a while, the flower's toxins cause the three to fall into a coma. Lex, unhappy that Dr. Hamilton has spent his time resurrecting dangerous flowers, has a team of specialists create a cure for Jonathan, Lana and Pete.

Ryan James (Ryan Kelley), a young boy who can read minds, is forced to use his ability to help his stepparents rob stores. Ryan escapes his stepparents and is taken in by the Kents, who are unaware of his ability. Ryan immediately bonds with Clark, whom he sees as his personal superhero. Ryan's stepfather finds him in Smallville, and kidnaps him. He attempts to use Ryan's abilities to steal Lex's trust fund. Clark comes to Ryan's aid before his stepfather can kill him. Ryan's aunt is located and she agrees to take custody of him.

Tyler Randall (Reynaldo Rosales), while trying to assist the suicide of his ailing mother, accidentally falls out of a window, and a piece of meteor rock becomes embedded in his wrist as he dies. When the coroner removes the rock from his wrist, Tyler becomes reanimated. Now, whenever Tyler touches someone, or something, they instantly incinerate and die. Believing he is helping, Tyler tries easing the pain of Whitney's dying father. Clark arrives in time to stop him, and informs him that his mother is still alive. Thinking his mother could not accept who he had become, Tyler takes his own life.

Class elections are being held, and Pete nominates Clark. Apprehensive at first, Clark soon takes to the idea. A rival candidate, Sasha Woodman (Shonda Farr), does not appreciate the competition and sends out swarms of bees to take care of the other competitors. Eventually, the bees become dissatisfied with Sasha's demands and turn on her. Lionel has a journalist write a scathing exposé on Lex, but Lex has the story dropped when he gets the journalist promoted to editor. Lana gets cutthroat with the Talon, and reports the rival coffee shop to the health board.

After a hit-and-run accident destroys his drawing hand, Justin Gaines (Adam Brody) is left with an unexpected gift of telekinesis. Justin uses his new gift to exact revenge on those who wronged him. Using Chloe to discover the identity of his hit and run driver, Justin sets out to kill the person who took his drawing hands. Justin kills Principal Kwan (Hiro Kanagawa), believing he was the driver who hit him, and turns on Chloe when she discovers what he has been doing. Clark knocks Justin unconscious before he can kill Chloe. Whitney's father, who has been battling heart problems, dies.

An explosion near meteor rocks gives Lana the ability to see through another person's eyes. Lana watches through the stranger's eyes as they kidnap Chloe. Teaming with Clark, Lana uses her gift to help locate Chloe. The kidnapper turns out to be a cop looking for an easy promotion. Whitney finds some military medals his father earned, and takes it as a sign he should do something else with his life. Lex learns of a ship that crashed during the meteor shower, and discovers an octagonal disc made of an alloy not found on Earth.

Lionel Luthor closes the Smallville plant and blames it on his son for not turning out a large profit as instructed; Lex decides to initiate an employee buyout of the local plant to save everyone's jobs and forge his own future with LexCorp. Meanwhile, Whitney decides to join the Marines and leaves Smallville. Learning the truth about Clark, Roger Nixon attempts to expose Clark's secret to the world. As Lana drives home after dropping Whitney off at the bus station, three tornadoes touch down, forcing her off the road. When the news is announced at the school dance, Clark leaves the dance to make sure Lana is okay. Just as Lana is pulled into a tornado, Clark arrives and speeds in after her.

Clark rescues Lana from the giant tornado which she was pulled into and takes her to the hospital. When he returns home, Clark learns that his ship is gone and that his father chased Roger Nixon (Tom O'Brien) into the storm for attempting to expose Clark's secret. Lex is wracked with guilt over not helping his father sooner when the mansion ceiling collapsed. Lex makes a decision to rush into surgery to keep his father from becoming paralyzed. The surgery succeeds but results in the loss of Lionel's eyesight. Jonathan and Nixon attempt to dig themselves out of the crypt they fell into after a mobile home dropped out of the sky on top of them. Clark shows up before the two men lose all oxygen, but the meteor rocks in the crypt weaken him. Nixon takes advantage of the situation and kidnaps Clark. Jonathan chases him, but Nixon gets the upper hand. Lex shows up and saves Jonathan's life by shooting Nixon before he can kill Jonathan.

During a record heat wave, Clark develops a new ability, heat vision, which causes him to have uncontrollable bursts of heat from his eyes. Clark quickly learns that his flare-ups are based on a state of sexual arousal, having started a fire at school and the local coffee shop while with Lana. With Jonathan's help, Clark is able to gain control over his new ability. Meanwhile, Lex marries Desirée Atkins (Krista Allen), a woman he barely knows and Clark's new biology teacher. Desirée has the ability to control men with pheromones enhanced by meteor rock. Desirée attempts to use her pheromones on Clark, but he is resistant. As a result, Desirée uses her abilities on Jonathan, convincing him to kill Lex so that she can inherit his fortune. Clark manages to save Lex before either Jonathan or Desirée can kill him.

Pete unknowingly discovers Clark's spaceship in a cornfield and makes plans to sell the story to the media. Against his parents' wishes, Clark decides to tell Pete the truth about his alien origins in an effort to keep Pete from telling anyone about the ship. Pete, more upset over Clark's dishonesty than the fact that he is an alien, leaves. Dr. Steven Hamilton (Joe Morton), suffering from overexposure to the meteor rocks, steals the spaceship. When Lex refuses to believe his rants about a ship, Dr. Hamilton seeks support from Lionel Luthor. After realizing that the ship requires a key to open it, Dr. Hamilton kidnaps Pete in an effort to find out where the key is. Dr. Hamilton threatens Pete's life before Clark arrives and rescues Pete. In the process, Dr. Hamilton has a violent convulsion, as a result of his condition, and dies. After returning the ship to the Kent farm, Pete and Clark reconcile.

Clark goes against his father's wishes and purchases an expensive Class ring. Unknowingly to him, the ring contains a red meteor rock, something he had previously never seen. The red meteor rock affects Clark mentally, stripping away his inhibitions. With his restraint gone, Clark begins to act out of character. Clark asks Lana out on a date, but ditches her in the middle for another girl when Lana does not like how he is acting. Showing resentment toward his parents for forcing him to live the life of a farm boy, Clark decides to use his abilities to become rich and leave Smallville. Pete and Jonathan must work together to stop Clark, who goes after a young girl and her father who are on the run from mobsters. Using green meteor rock to weaken Clark, Jonathan smashes the ring with a sledgehammer. Later, Clark tries to apologize to his parents, but Jonathan suspects that Clark was expressing his true feelings.

While visiting her parents' grave, Lana finds a love poem left for her. The poem was written by a boy named Byron Moore (Sean Faris), whose parents never allowed him to leave the house. Clark and Lana suspect that Byron is being abused, but when the police investigate Byron's parents say that he died years earlier. Clark and Pete break into the home the next day and find Byron locked in the basement. When Byron is brought into the sunlight he transforms into a violent creature with superhuman strength. It is revealed that Byron had a deadly disease and was a test subject for one of LuthorCorp's projects run by Lionel Luthor. Byron goes after Lionel, but Clark tracks him down and slams him into a well shaft and out of the sunlight. The darkness returns Byron to normal long enough for Clark, with Lex's help, to get Byron to the hospital. Meanwhile, Martha takes a position as Lionel's personal assistant, much to the dismay of Jonathan and Clark.

When a student is pulled out of the school pool, having aged 60 years in a few seconds, Clark and Chloe decide to investigate. They discover an 80-year trail of similar events left behind by Chrissy Parker (Maggie Lawson), another student at Smallville High, and deduce that she is draining the life force from her victims in order to stay young. Missy goes after the new school principal, but Clark manages to get there in time to stop her. Without a fresh victim, Missy's body begins to age rapidly until she deteriorates into dust. Meanwhile, Lana discovers a photo of her mother in a romantic pose with an unidentified man during a period of time when she believed her parents were happily married. Lana asks Lex to investigate who the man is, and she eventually learns that her parents were legally separated at the time of the photo and that the man in the photo could be her biological father.

A woman named Rachel Dunleavy (Blair Brown) shows up claiming to be Clark's biological mother, and that Lionel was his biological father. Clark finds the truth about his adoption. Clark dismisses her claims, but Rachael files a court order to have a DNA test performed. Clark and Pete sneak into the testing labs, and Clark swaps Pete's DNA for his so that the technicians do not figure out that he is not human. When the results come back negative, Rachael kidnaps Lex in an effort to force Lionel to admit that he fathered a child with her and that Clark is their son. Rachel witnesses Clark using his abilities when he rescues Lex and realizes that he is not her son. Lionel later admits to Lex that he did father another child, but that it died as an infant. Later, Lionel is seen with a locket and a picture of a young boy. Meanwhile, Lana finds the man from the photo, Henry Small, who eventually agrees to do a DNA test to determine if he is her father.

After his aunt abandons him because she can't handle his secret, Ryan (from the first season episode Stray) phones Clark for help. Clark rescues Ryan from the Summerholt facility, where the boy was being held an unwilling subject of experimentation, and brings him back to Smallville. He soon finds out that Ryan has a tumor in his brain, and that he only has a couple days left to live.

Ian (Jonathan Taylor Thomas), a straight-A student, has the ability to duplicate himself. He uses his power to take extra classes and to date Lana and Chloe at the same time. Clark and Pete reveal Ian's secret, which induces Ian to try to kill both girls. Meanwhile, Lex attends an anger management session, where he meets Dr. Helen Bryce.

Clark stumbles into a local Native American cave, located below a new LuthorCorp construction site, and discovers symbols in an alien language on the cave walls. A local Native American, Joseph Willowbrook, and his granddaughter Kyla, recount a story that reflects Clark's life. In an effort to save the land, Kyla tries to scare the Luthors away, using her ability of skin-walking, but she is mortally injured during her attack on Lionel.

Whitney Fordman returns from overseas, claiming to have lost some of his memory during battle. Therefore, he attempts reuniting with Lana, ignorant of the Dear John letter she sent. Not wanting to hurt him, Lana submits to his attempts to win her back, but Clark discovers that Whitney is actually Tina Greer (from the first season episode X-Ray). When Clark confronts Tina, she immobilizes him using green meteor rock. Left helpless in the Kents' storm cellar, Clark is saved by his spaceship. During a later confrontation with Clark, Tina injures herself and dies. It is subsequently revealed that the real Whitney was killed in action.

After Lex is defeated in a takeover bid by Lionel, he discovers that his mansion is full of listening devices. Lex starts a plan to bug LuthorCorp's headquarters, but aborts when he finds out that Martha and Lionel are headed there. The abort is botched when the workers want to steal from the LuthorCorp vault. While held hostage, Martha learns that Lionel has files on Clark and bars of refined meteor rock. She also retrieves the ortagonal disc and stores it in a flour jar in the kitchen.

Lionel is mysteriously shot at the Luthor mansion, leaving behind a huge list of suspects with various motives to want him dead. Jonathan, who is found unconscious in his truck with a bottle of tequila and a gun in his hand, is arrested as the prime suspect. Clark and Pete investigate and discover an elaborate plan orchestrated by Sheriff Ethan.

Pete and Chloe are infected by bug-like creatures that burrow into the necks of those who get close enough. The bugs cause people to engage in extremely risky behavior. Meanwhile, Clark finally asks Lana on a date. This infuriates a jealous Chloe. Pete uses red meteor rock to get Clark to join them in their adrenaline-rushing behavior. Chloe tries to seduce Clark, and the red meteor rock is incidentally removed, restoring Clark to his normal self. Clark manages to get both his friends to the hospital, but he ruins his evening with Lana. Lex hires Dr. Frederick Walden, an expert in ancient glyphs, to try to translate the language found on walls of the Kawatche Caves.

Lex discovers that his half-brother, Lucas, is still alive. Lionel has been looking after Lucas, and he uses him to steal Lex's inheritance, so he cannot buy-out LuthorCorp. Penniless, Lex moves in with the Kents. Lucas, dissatisfied with Lionel's plans for him, discovers that Lionel has been faking blindness for a while. An elaborate scheme with Lex reveals Lionel's lie, and Lex secures his inheritance.

Martha, who has been hiding the key to the spaceship, becomes extremely sick from inhaling the dust of green meteor rock that was underground. The Kent farm is quarantined, and the key discovered. Clark, who inhaled the meteor dust as well, falls sick too. While Clark is unconscious, Chloe reads him a note describing her true feelings for him, only to have him mumble Lana's name in his sleep. After testing his blood, Dr. Helen Bryce realizes that Clark is different. Martha is revealed to be pregnant after the ship removes her poisoning.

Clark decides to place the key into a slot in the cave wall. Upon inserting the key, the wall instills him with the language of the cave. Dr. Walden discovers the key and uses it himself, but the information overload puts him in a coma. At home, Clark's heat vision forces him to etch a symbol onto the barn door. He is contacted by Dr. Virgil Swann (Christopher Reeve), who educates Clark about Krypton, his home planet. Using the key on the ship, he uncovers a hidden message from his biological father stating that his destiny is to conquer Earth.

A classmate at school, Cyrus, displays special abilities. Clark discovers that Cyrus believes he is an alien who arrived during the meteor shower, leading him to believe Dr. Swann was wrong when he told Clark he was the only Kryptonian on Earth. Cyrus shows Clark the transmission tower he is building to contact his alien parents, but evidence surfaces that proves that Cyrus is human.

After Lana is assaulted by a college student, Andy Conners, Clark loses control and seems to injure the boy. When the Kents are sued for punitive damages, Clark begins to question his powers, while trying to find a way out of the lawsuit. It is later revealed that Andy was faking his injuries, and, thanks to a plan concocted by Lana, Clark, and Chloe, he is exposed. Meanwhile, Helen's ex-boyfriend arrives in town, intent on winning her back. When she turns him down, he stabs her, prompting Lex to take the law into his own hands.

Eric Marsh, a baseball player at Smallville High, hijacks a LuthorCorp van along with two other thieves and steals a shipment of refined green meteor rock. Clark stumbles upon the robbery, but is no match for them. It turns out that Eric and his crew are manufacturing and inhaling liquid kryptonite, which leads to enhanced strength that rivals that of Clark's natural one. Eventually, however, Jonathan reminds a discouraged Clark that although Eric's gang has strength, they don't have any of Clark's other powers. As a result, Clark was able to subdue the trio of thieves and prevent them from pulling another job. Meanwhile, Lionel offers to fund the Torch and a position at the Daily Planet to Chloe.

Lana thinks she is seeing ghosts, when an old childhood friend, Emily Eve Dinsmore, who died six years earlier, appears. Clark discovers that the child is indeed real. By moving extremely fast, the girl seems to disappear and walk through walls. Clark learns that Emily's father has been cloning her, with the help of green meteor rock. The flaw with the Emily clone is that she has no sense of morality, which eventually puts Lana in danger. Meanwhile, Lex prepares for his wedding with Helen.

Dr. Walden wakes up from his coma, and tells Lex and Lionel that Clark is an alien that must be destroyed. A romantic encounter between Clark and Lana is quickly dismissed when Chloe finds out they are together. During a rehearsal for Lex and Helen's wedding, Clark hears a strange voice calling from the storm cellar.

The will of Clark's biological father, Jor-El, informs Clark he must leave Smallville. Not wanting to leave his family and friends, Clark steals Lionel's copy of the spaceship key made out of refined green meteor rock and sticks it into the ship, destroying it. The blast from the explosion causes Martha to lose her baby. Grief stricken, Clark starts using red kryptonite and decides to leave Smallville. During his honeymoon flight, Lex wakes to find the plane going down and Helen and the pilot missing.

Under the influence of red kryptonite, and living in Metropolis, Clark gets involved with a crime lord named Morgan Edge who hires him to break into LuthorCorp. Desperate to put his family back together, Jonathan makes a deal with Jor-El so that he can bring Clark home. Lex is stranded on a deserted island, with the world believing him to be dead. At the mansion, Lionel accuses Helen, revealed to be alive, of killing Lex.

Jor-El grants Jonathan temporary superpowers, and he and Clark engage in a destructive battle below the LuthorCorp building. Clark, unable to kill his father, destroys the red kryptonite. Lex returns home to the shock of Helen. He quickly learns that Helen attempted to kill him, and takes measures to ensure that doesn't happen again. Morgan Edge finds Clark and kidnaps him in an effort to make amends to Lionel.

Clark discovers Van McNulty has been killing green meteor rock-infected people. When he confronts him, the green kryptonite rock Van is carrying stops him. Knowing Clark's weakness, Van manufactures meteor rock bullets, and almost kills Clark. Using Lana as bait, Van tries to increase his efforts, but both Lana and Clark prove to be too much for him to handle.

A comatose girl, Sarah Conroy, has the ability to pull Clark into her dreams, and does so without warning. Clark and Lana visit her, and grow suspicious of her uncle when they learn of Sarah's inheritance that he oversees. They discover the uncle has been drugging her to keep her in a coma. When Nicholas Conroy finds out, he tries to kill Lana, but Clark arrives in time to stop him.

Clark discovers his abilities are derived from the Sun, when an increase in solar flares cause his powers to either flare up, or give out completely. Perry White, a once promising journalist, arrives in Smallville in search of stories for a tabloid news show. Despite being constantly inebriated, Perry believes he witnessed Clark using superhuman abilities, and devises a dangerous scheme to expose the truth.

Lana's great uncle, who was convicted of murdering his wife forty years prior, shows her a picture of a drifter he believes really killed her aunt. The drifter looks just like Clark. Positive that the man is Jor-El, Clark's investigation leads him to a Kryptonian medallion that allows him to see moments of the past, and also lets him see how human Jor-El was when he first came to Earth.

When Lana starts seeing a new guy, and begins acting out of character, Clark investigates. Clark's suspicions are confirmed when he discovers Lana's new boyfriend has magnetic powers that can move objects and alter human emotions. When he tries to free Lana from the magnetic hold, she tries to kill Clark. Lex discovers Chloe has been digging into Lionel's past and tries to get her to join him in his fight against his father.

Lex locates Morgan Edge and gets him to admit that he helped Lionel murder his parents. Before Lex can take it to the authorities, someone tries to kill him. Lex flees and asks Clark for help. Evidence begins to amount that suggests Lex has had a psychotic break. Lex watches Clark slam into Edge's car, after Clark pushes him out of harm's way. Lex's doctors arrive and take him to Belle Reve sanitarium.

Lex attempts to convince Clark to help him escape, but when Clark refuses, he attempts to escape by himself. His resulting capture forces Lionel to send him in for electroshock therapy to erase his memory. Ian Randall, Eric Summers, and Van McNulty band together in an attempt to steal Clark's powers and escape. Lana, at the hospital after a near fatal accident caused by Lex, meets another patient, Adam Knight, who pushes her to fight the pain and finish her rehab.

Attempting to stop a robbery, Clark is temporarily blinded when he shoots off a burst of heat vision that is reflected back into his eyes by a piece of green kryptonite. He soon realizes that his body has developed super-hearing to compensate for his lack of sight. Pete is kidnapped by one of the thieves, in an attempt to blackmail the judge, Pete's mom, into dismissing the charges against his partner. Clark tries to gain control over his hearing so that he can find Pete.

When Chloe uncovers a secret experiment at Summerholt Institute, someone begins sending mind-controlling emails to her friends with orders to kill her. Clark and Lex discover the person responsible, Molly Griggs, but cannot tie her to Dr. Garner. Lana decides to rent the apartment above the café to Adam, even though she feels he is hiding something dangerous about his past.

Clark learns his schoolmate Jordan can foresee the future death of anyone he touches. Jordan warns him that Lana is going to die in a fire in the next few days. Clark sets out to prevent Lana's death. Jordan also tells him that he didn't see a death in Clark's future. Chloe, suspicious of Adam, begins investigating him, and uncovers disturbing news.

Pete begins street racing with kryptonite-infused cars. When he refuses to throw a race, the people in charge threaten to kill him. He asks Clark to use his powers to help him. Pete challenges the leader to a race, but when Clark overhears their plan to blow up Pete's car, he tries to stop the race. Meanwhile, Jonathan begins to show the effects of his deal with Jor-El.

When Clark is forced to use his powers in front of another student, Alicia Baker, he is surprised to find out she has powers of her own. The two develop a bond through their shared secret, but things change when Alicia becomes obsessive about sharing Clark with anyone else – especially Lana. Lana, fearing for her own safety, asks Lex to get rid of Adam.

While his father awaits surgery, Clark befriends a young boy, Garrett, whose brother Vince just died from liver failure. Everyone is shocked when Vince shows up at the Kents' alive. When his liver starts failing again, Garrett straps a kryptonite bomb to himself and demands that Vince be given Jonathan's liver or he will blow up the building. Clark learns that Lionel has been using a sample of his blood to bring the dead back to life.

Clark receives a panicked call from Lana and hears a gunshot before the line goes dead, but when he arrives at the Talon he discovers she is alive and well. Clark, Chloe and Lana realize the phone call came from one day into the future, and that Adam is the one who will shoot Lana. When Lex takes Clark to the Luthorcorp lab where Adam is being kept, he finds all of the staff murdered, and Adam missing.

Clark begins to suspect that Jor-El is sending Jonathan messages through the key, and that he is the cause for his father's withdrawal from the family. Clark goes down to the caves to confront his biological father. Lionel catches him there and begins putting the pieces together, which leads him to Dr. Swann. A deal is struck, and Lionel's true motives are revealed.

When Chloe accidentally inhales a mysterious kryptonite-gas, she discovers it acts as a truth serum to anyone who comes in contact with her. She decides to take advantage of her new power by attempting to uncover Clark's secret. However, her new power comes with fatal consequences. Clark sets out to find an antidote before Chloe can discover the truth about him, rescuing her just when she's about to die.

Believing that key information about his father's past was lost when his memory was erased, Lex decides to join an experimental program with Dr. Garner to regain his memory. Knowing that Lex will discover his secret if he regains his memory, Clark tries to stop him, but is caught by Lionel and Garner so that they can experiment on him. Through the experiment, Clark learns about his birth mother.

When a Kawatche Indian, Jeremiah Holdsclaw, steals a mythic knife from the caves, he is bestowed with superpowers similar to Clark's. Believing he is the true Naman, he sets out to find and kill Lionel. Lionel attempts to find the knife, while Clark learns that it will crumble if the real Segeth touches it. Clark tries to find Jeremiah before he can kill Lionel.

After learning that Lana is leaving Smallville, Clark decides to tell her his secret so they can finally be together. FBI agent Frank Loder kidnaps and tortures Pete to try to force him to reveal Clark's secret. Lex panics after the FBI gives him 24 hours to turn over information on his father or face jail time for the murders of the lab technicians at LuthorCorp. Chloe helps provide text of a conversation between her and Lionel, with Lionel admitting his hand in his parents' death. Emily Eve Dinsmore, the six-year-old girl (from the episode 'Accelerate') had matured into a grown-up and still obsessed with Lana, escapes from the institute where she is interned and kidnaps Lana.

A young girl, calling herself Kara and claiming to be from Krypton, arrives at the Kents' to entice Clark to fulfill his destiny. Clark turns to his parents for advice, but is shocked when the girl forces Jonathan to finally reveal the deal he made with Jor-El. Clark makes a discovery that ultimately redefines his relationship with Lex, and Clark's relationship with Lana takes a final turn when she leaves for Paris. Clark gets taken by Jor-El with Jonathen half strangled to death. A Kryptonian symbol is burned onto the Kent farm land, and Lionel has his head shaved in prison as Lex is poisoned and Chloe is presumably killed in an explosion.

Clark returns to Smallville as Kal-El; intent on fulfilling his destiny, Kal-El takes to the skies to steal a powerful Kryptonian stone which was in the possession of Lex Luthor. Dr. Swann's emissary, Bridgette Crosby (Margot Kidder), arrives to help Martha, who learns about a new form of kryptonite. Lois Lane comes to town to investigate the death of her cousin Chloe. Lana is shown in Paris with a new boyfriend, Jason (Jensen Ackles), and Jonathan Kent lies in a coma. Martha uses the Black kryptonite to help Clark retrieve his past self. Lana sees a symbol on her back which is similar to one on tombstone of Countess Isobel Thoreaux.

Clark and Lois Lane investigate Chloe's apparent death, but are stopped by General Sam Lane, Lois' father. Lois suspects he knows more about Chloe's death than he is letting on, and tries to find out more. Discovering that Lex has been keeping her in hiding, Clark tries to find Chloe before Lionel's assassin can really kill her.

Lana's boyfriend, Jason Teague, having followed her to Smallville, takes a position as the assistant football coach. The two try keeping their romance a secret from the school, and also Clark. Abby Fine, a student, turns to plastic surgery to enhance her looks and boost her popularity. Things go awry when she discovers that her kryptonite-enhanced beauty causes harm to anyone she kisses.

The cheerleading squad spikes the football player's drinks with a kryptonite-enhanced love potion. The result allows Clark to become the starting quarterback for the school. It also causes Chloe to become devoted to Clark, and sends a jealous Jason after Clark. Clark and Lois investigate and uncover the truth, and the key to removing the trance.

Clark attempts to track down Bart Allen, a thief who stole Jonathan's wallet, but he's faster than Clark. Later, Bart arrives at the farm to make amends. Lex buys a manuscript with Kryptonian symbols, and Clark discovers that it contains a hidden map to one of the Kryptonian stones. When Bart steals the manuscript, he inadvertently puts Clark's life in danger and must make the decision to save Clark or himself.

One of the stones begins calling to Clark, who speeds to the prison where Lionel is held. When he sees Lionel attempt to stab Lex with the stone, Clark grabs for it, causing the two men to switch bodies. Learning his new body has super powers, Lionel immediately begins wreaking havoc in Smallville. Trapped behind bars without his powers, Clark tries to figure out a way to get his body and powers back in order to save his friends and family.

Foreign-exchange student Mikhail Mxyzptlk has the power of persuasion, and uses it to fix sporting events. Clark and Chloe try to figure out how he is controlling everyone. Mikhail makes a bet with Lex to keep his citizenship, but Clark and Chloe discover his weakness, preventing him from controlling the game. With his powers lost, Mikhail surrenders to Lex, but Lex decides to take him to a secret lab, 33.1, where he hopes Mikhail will regain his ability.

After Lana reads from a spell book, she becomes possessed by the spirit of Isobel Thoreaux; Lois and Chloe also become possessed by witches that were burned at the stake in France during the 1600s. The three witches seek revenge for their burning, as well as the Kryptonian stones. Clark attempts to stop the witches, but they strip him of his powers, shackle and torture him, and force him to reveal the location of the stone he hid in the cave. Eventually, however, Clark is freed by Jason Teague and confronts the witches in the cave. There, he regains his powers and uses his heat-vision to destroy the spell book and free Lana, Lois, and Chloe from possession.

Lex is accused of killing a young woman, and Clark sets out to prove his innocence. Swearing he is a changed man, Lionel offers Clark insight into the crime, but he asks for something in return. Meanwhile, Lana meets Jason's mother, Genevieve Teague, and has a vivid flashback of the incident in Paris, leading her to suspect that Jason's mother was there when she got her tattoo.

Lex's secret experiment at LuthorCorp goes awry and causes a dangerous toxin to be released into Smallville. Those infected by the toxin, including Clark, Lana, Chloe, Lex, and Jason, imagine their greatest fears come true and then fall into a coma. Desperate to find a cure, Clark heats up the vials containing a cure while Lex is not looking. With the cure heated to the correct temperature, Lex does something unexpected with the unproven antidote.

Claiming to be cured, Alicia Baker is released from Belle Reve and returns to Smallville. Initially skeptical of Alicia, Clark finds himself enjoying a relationship with someone who knows his secret. When she pushes for more he hesitates, causing her to use red kryptonite on him. A morally challenged Clark emerges and whisks Alicia off to get married. Lana decides to have sex with Jason in an effort to win him back.

Clark has concerns after Alicia becomes the prime suspect in a brutal attack against Lana and Jason. Initially defending Alicia, Clark begins to think differently as the evidence begins to pile up. Hurt, Alicia forces Clark to unknowingly reveal his powers in front of Chloe. Afterward, she is killed by the person who was truly responsible for the attacks, Clark finds her and is deeply affected as he loved her. Jason's mother returns to town with an offer for Lex.

In an effort to recruit Clark for their football team, Metropolis University sends their star player Geoff Johns to show Clark the perks of attending Met U. However, after one of Metropolis University's players dies under mysterious circumstances, and Lois is arrested for his murder, Clark discovers that Geoff has super powers and is using them to paralyze anyone who gets in his way, including Lois. Meanwhile, Chloe attempts to learn more about Clark's secret.

While driving, Lois accidentally hits a dog and brings it back to the farm. Clark realizes it's not an ordinary dog when it drags a tractor across the lawn. Clark and Lois learn the dog was stolen from an aborted LuthorCorp experiment, and was now being used to commit crimes. Lex lets Clark keep the dog, whom Martha named Shelby. Meanwhile, Lana questions Jason's involvement in his mother's schemes.

After learning that Jason and Lex are in China searching for one of the Kryptonian stones, Clark and Lana follow in the hopes of finding it first. Clark finds an artifact that leads them to the stone, but he must battle Isobel Thoreaux, the witch who possessed Lana, who has returned to take the stone for herself. Lex has more information on the stones than he is letting on.

Lois' younger sister, Lucy, comes to town and charms everyone she meets. However, Clark discovers a darker side to Lucy, after he catches her stealing money from the Talon, and forces her to reveal the truth about her sudden appearance in Smallville. Meanwhile, the stone from Shanghai disappears from Lana's apartment and Jason accuses Lionel of stealing it.

A glimpse of the future Lex Luthor is revealed after a kryptonite explosion splits Lex in two, (Alexander) and his evil side – Lex – are released. Lex immediately imprisons Alexander in the mansion, and tries to kill Clark and Chloe. After discovering Clark's secret, he attempts to persuade Clark to join him. Clark uses black kryptonite to force the two Lexes back together.

A stunned Chloe is nominated for Prom Queen, and tries to talk a reluctant Clark and Lana into attending the dance with her. However, after her rival Dawn crashes her car into a ravine filled with kryptonite, Dawn's spirit is released, allowing her to enter the bodies of anyone she wants. As a result, Lana asks Clark to be her date, Lois attends the Prom and Chloe attempts to set the school on fire.

Kevin, a boy who can cause people to temporarily lose their memory, turns his powers on Clark and causes him to have total amnesia. Chloe discovers what has happened and must teach Clark about his superpowers, while simultaneously trying to keep him from accidentally revealing them to others. Without his memory, Clark meets and falls in love with Lana again. Lex takes advantage and convinces Clark to reveal the cave secrets.

Clark and Lana discover an abandoned baby in the cornfield and take him back to the Kent farm. However, once the baby ages from a newborn to sixteen years old in a matter of days, the two realize he is aging at a rapid rate and frantically search for a cure before the disease kills him.

Clark must stop the school photographer after he sets up a secret simulated high school and begins kidnapping students to keep the glory days of high school going forever. Lex and Lionel are kidnapped and tortured by the Teagues in an effort to find the Kryptonian stone. However, after Genevieve realizes Lana has it, she decides to put an end to the hunt once and for all.

Genevieve confronts Lana, but Isobel takes control and kills Genevieve, subsequently releasing Lana from possession. As a result of using a Kryptonian stone to kill a person, a menace comes to Smallville (under the guise of a second meteor shower that threatens the city), and Clark is forced to listen to Jor-El and retrieve all of the stones at once. Clark races across town to retrieve the Kryptonian stones, and puts them all together in the cave. Lex forces Chloe to accompany him to the caves, where they see Clark standing in a blinding light. Lana's helicopter crashes next to a newly arrived spaceship, and Clark is transported to the Arctic.

Transported to the Arctic, Clark watches as the united crystals create the Fortress of Solitude. Inside, Jor-El instructs Clark that he must complete training for an impending doom that is about to hit Earth. Meanwhile, two Kryptonian disciples of Zod arrive in Smallville searching for Kal-El. Clark is forced to return to Smallville, before completing his training, but promises Jor-El that he'll return before sunset.

When he doesn't return, Jor-El strips Clark of his powers, making him normal. Delighted to finally be human, Clark pursues a relationship with Lana without secrets. When Lana, Jonathan and Martha are taken hostage by three krypto-thugs, Clark must figure out how to save his family without his super powers. In the end, Clark learns that everything was orchestrated by Lex, in an effort to test Clark's abilities. Clark confronts Lex, thus ending their friendship.

Chloe is warned by Gabriel, a former school newspaper worker, that he is going to set off a missile and obliterate all of Smallville. Still stripped of his super powers, Clark confronts Gabriel and ends up being killed. Jor-El, in possession of Lionel's body, resurrects Clark with all his powers, but with the consequence that someone Clark loves will have to die.

Lois injures herself in the lake, but before Clark can rescue her, a mysterious swimmer, Arthur A.C. Curry, out-swims Clark and rescues her first. During his first lecture at a University, Professor Fine (James Marsters) tells Clark that Lex is behind a covert operation manufacturing weapons. The same weapons are what brought A.C. to Smallville. Teaming up with Clark, the two destroy Lex's underwater weapon, and Clark's trust of Lex disappears completely.

Lana decides to enroll at Metropolis University at the last minute and is forced to join a sorority to find housing. The house leader Buffy Sanders, and her sorority sisters, offer her more than a place to crash when they turn her into a vampire. Lex provides Clark with an antidote for Lana, after LuthorCorp is revealed to be connected to the vampires. Chloe earns an internship at the Daily Planet.

Senator Jack Jennings (Tom Wopat), Jonathan's oldest friend, arrives at the Kent farm looking for support in his campaign for re-election. When a stripper turns up dead, and is revealed to be Jennings' mistress, Jennings is made the prime suspect. Searching for answers, Chloe convinces Lois to go undercover as a stripper, but things take a dangerous turn when Lois is kidnapped by a foreign diplomat's son, who intends to sell her into slavery.

Clark is exposed to a new kind of kryptonite, causing him to have paranoid delusions about those around him. The silver kryptonite makes him believe that Chloe is going to reveal his secret, Jonathan is scheming against him with Lionel, and Lex and Lana are having a secret relationship. Chloe and the Kents frantically search for a cure, but it is Professor Fine who comes to Clark's rescue, claiming to be a Kryptonian.

When Martha contracts a strange disease, Clark turns to Professor Fine, who convinces Clark that Jor-El is the one responsible for her illness. Fine convinces Clark that the only way to save her is to destroy the Fortress of Solitude, separating Jor-El's link. Once the two arrive at the Fortress, Fine reveals himself to be an artificial intelligence created by Kryptonians and tries to free Zod from the Phantom Zone.

Lex considers finding, or creating, damaging information against Jonathan to upset his Senatorial race, information that may harm Clark and Martha. When Lex is shot, he falls into a coma and is visited by the ghost of his mother. She shows him a life without his father, where Lex is married to Lana, and the two are expecting a second child. Interrupting Clark and Lana's first Christmas, Chloe persuades Clark to play Santa, and deliver gifts to those less fortunate.

Jonathan's life is threatened by a mysterious source, who urges him to drop out of the race. Clark discovers that Lex's followers, primarily Samantha Drake, are determined to do anything to see that Lex wins the election. Lois is threatened into assassinating Jonathan during his senatorial speech. Lionel offers Martha some money to help Jonathan's campaign, while Lana believes that the answers she is looking for lie in the first meteor shower.

Two police officers, one of whom witnessed the Kryptonians land in the second meteor shower, take Lex and Lana hostage and threaten to kill them unless Lex reveals where he hid the spaceship. Lex takes a bullet meant for Lana, and fearing Lex may bleed to death, Lana asks him to tell the officers the location. Clark discovers Lana has been researching the spaceship with Lex and fears she is close to discovering his secret.

Clark is finally willing to reveal his secret to Lana, but there are consequences. Jonathan and Lex learn the results of the senatorial election and the life of someone Clark loves – Lana – is finally taken away from him. A desperate Clark appeals to Jor-El for help, only to find himself frantically trying to save her again. Lionel reveals to Jonathan he has a little more up his sleeve. Minutes later, Jonathan dies of a heart attack in front of Martha and Clark.

When his mother is mugged in Metropolis, Clark decides to find out who it was that saved her life. He discovers the new reporter at the Daily Planet, a woman named Andrea Rojas, is actually a masked avenger who fights crime at night. Clark’s bottled-up grief over the loss of his father threatens to get the best of him as he joins Andrea in her fight against crime.

The spirit of a young girl is released from her tomb after lightning strikes a kryptonite bracelet she was wearing. Clark finds the corpse in the walls of the Talon and it attaches itself to Chloe. Clark follows the trail of the spirit to find her killer, who has been preying on girls in Smallville for the past decade. When Lois is suddenly kidnapped, Chloe has to come to her rescue.

A sympathetic doctor releases a half-human/half-machine subject named Victor Stone being held captive and experimented on by LuthorCorp. Clark befriends Victor and promises to help him find his girlfriend, but Lex traps Victor and takes him back to LuthorCorp. Clark helps Victor free himself for good. Meanwhile, Martha is being blackmailed, and Lionel offers to step in and deal with the blackmailer. It is later revealed that Lionel knows Clark's secret.

Lex goes searching for Professor Fine in the jungles of Honduras. Clark meets a beautiful seductress named Simone who uses a magical charm to make people succumb to her every wish. An enchanted Clark reveals his powers to Simone, who seizes the opportunity and, after forcing Clark to break up with Lana, demands Clark kill Lex. Lana tries to reconcile her and Clark's relationship, but Clark breaks up with her thinking that they can never be together because of his secret identity.

Chloe discovers that Professor Fine is still alive and warns Clark, who sets out looking for him. Lana, still upset over her break-up, experiments with a kryptonite drug that allows her to see her deceased parents. A worried Clark rushes to save Lana from hurting herself, but ends up being injected with the kryptonite-laced serum. When Clark flat-lines, he is able to talk to his father, who warns him that Lionel knows his secret.

Clark and Martha take in a little girl, Maddie, after her foster mother is brutally stabbed to death. Maddie becomes the prime suspect, at least in Lois' eyes, when it is discovered that she has the power to manipulate glass. Maddie's father arrives to claim her, and is revealed to be the real murderer. Lois takes a job as Martha's Chief of Staff, and Chloe walks in on Lex and Lana during an intimate moment.

After a failed take-over of LuthorCorp, a disgruntled employee takes Lionel hostage and orchestrates a series of elaborate games that Lionel must win in order to stay alive. After Clark tells Martha that Lionel knows his secret, she inadvertently becomes a pawn in the tormentor’s game and ends up fighting for her own life.

While in Metropolis, Clark saves the life of a stranger named Graham, who vows to repay Clark for his kindness. Unfortunately, Graham happens to be a hit man with the ability to cloak himself, and he decides killing Lex would be the best gift he could give Clark. Meanwhile, Lana tells Clark about her growing relationship with Lex.

Clark is stunned when he sees his father’s ghost at the graveyard, but becomes even more confused when Jonathan tells him he must kill Lionel. Jonathan appears again, and gives Martha the same message. Lex develops a vaccine for Fine’s deadly virus, but Fine intervenes and injects him with the vaccine. Clark realizes Jonathan is really Milton Fine, and Jor-El takes possession of Lionel so that he can destroy him.

Fine unleashes a crippling computer virus, which will lead to the destruction of Earth via pandemonium, and refuses to stop it unless Clark agrees to release Zod. Clark turns to Jor-El, who informs him that Zod needs a vessel to inhabit. Clark must destroy that vessel, and that vessel is Lex. Lex is stunned by his newfound powers and shares the discovery with Lana, who decides to stand by her new man, unaware of Fine's true intentions.

Clark, still stuck in the Phantom Zone, gets help from his father's assistant, Raya, in escaping. Chloe runs into former flame Jimmy Olsen, a new intern photographer at the Daily Planet. Clark returns from the Phantom Zone and confronts Zod. Using the House of El crystal Raya gave him, Clark defeats Zod. It also becomes apparent that other Phantom Zone criminals escaped with Clark.

Clark spends his nights helping the rebuilding effort of Metropolis. When Clark develops a cold, he discovers a new super power. An inadvertent sneeze blows the barn door off its hinges and across town, nearly striking Lois. While seeking the truth behind the falling door, Lois discovers a new love for investigative journalism. Oliver Queen, one of Lex's old classmates, moves to Metropolis. He has Lex captured to investigate Lex's powers.

Lex throws a costume charity ball to help raise funds for the restoration process after Dark Thursday. Lana has conflicting feelings about trusting Lex, and she confides in Chloe. Clark learns that others have escaped the Phantom Zone when he and Chloe discover Gloria, a park ranger, is kidnapping men to harbor her alien seeds.

A thief crashes Lionel's party for Martha's U.S. Senate bid, and steals a priceless necklace from Martha. Clark goes to Metropolis to find the necklace, and quickly discovers that Oliver is the thief. Lois believes she's landed a new front page story with the Inquisitor, calling the thief Green Arrow, but her story is ruined when he steals her only evidence.

Lex and Oliver attend their 10 year reunion, where the animosity between them is obviously rising as talk of Lex's deceased best friend, Duncan, brings tension. When Oliver's old friends begin to die one by one, he starts an investigation into who is responsible. Oliver gives Clark the satellite images from Dark Thursday, in exchange for helping him find out who is killing his friends.

An escaped phantom, Baern, takes possession of a young boy's body (Bow Wow) and sets his sights on finding Kal-El. As Clark is studying the satellite images, he gets an unexpected visitor, Raya. The escaped Zoner locates Clark and arrives at the Kent Farm, but is forced to retreat. Baern returns with more power, and after Raya is fatally injured, Clark uses the House of El crystal to capture Baern.

Oliver bails on Lois when a couple is being mugged at gunpoint. While attempting to stop the muggers, Oliver is shot. When Clark checks in on Oliver, Oliver has no visible signs of being shot. Clark and Chloe discover that Oliver's research facility is developing a drug that heals almost any wound instantly. Lana learns that she is pregnant.

Level 33.1 patient Bronson breaches the mansion and kidnaps Lex, transporting him to another frequency plane. Clark learns of another escaped Phantom Zone criminal and heads to Seattle to find him. Bronson kidnaps Lana, in an effort to force Lex to reveal the new location of 33.1. Jimmy triangulates their positions to pull them out, but not before Lex kills Bronson. Clark has his first encounter with The Martian Manhunter. Lex proposes to Lana.

Jed McNally is forcing illegal immigrants to work on his farm in Smallville. Javier, who has come to Kansas to search for his mother, manages to escape, but his friend gets pulled into the ground during the attempt. McNally is arrested, but escapes by burrowing into the ground. Chloe and Jimmy locate Javier's mother. Lex has McNally imprisoned in the newly relocated 33.1.

Linda Lake, a gossip columnist with the ability to morph into water, uses her ability to uncover incriminating stories, including one about Lana, Lex and Clark. Lois suspects that Oliver is actually the Green Arrow. She sets up an elaborate scheme to catch him, but Clark dresses up as Green Arrow and while in disguise, shares a passionate kiss with Lois, which both enjoy. Chloe and Linda get into a fight, when Chloe discovers Linda's new story about Clark. Clark learns about Lana's pregnancy, and she finally accepts Lex's proposal.

Bart, A.C., and Victor return to Smallville with Oliver. Oliver believes Lex is amassing an army of kryptonite-enhanced people in his level 33.1 projects. When Bart is captured, Clark and the others band together to rescue him and destroy Lex's facility. After completing their mission, Oliver says goodbye to Lois and leaves town with Bart, A.C., and Victor in search of Lex's other 33.1 facilities.

Clark is attacked by a Zoner, but when he wakes up he finds himself in a sanitarium, and without his powers. He is informed that his entire life, as he believes it, has been nothing more than a fabrication he created to cope with his biological parents' death in the meteor shower. Another patient tries to help Clark, warning him that the phantom is actually attempting to take over Clark's body.

During a Valentine's Day party, Lois is given a tube of lipstick laced with red kryptonite, designed to cause her to fall in love with the first person she sees. When Lois kisses Clark, he becomes immediately affected. Chloe and Martha quickly realize the truth and grab some green kryptonite to neutralize the effects. Before they can, a fight with Lex causes Lana to grow more suspicious about Clark's secret.

While Lana continues her investigation into Clark, someone else begins stalking her. No matter where she goes they continue to find her, leaving her gifts and death threats. Lana begins to fear for her safety. For safety, she stays with Martha, and uses the opportunity to learn more about Clark. When she returns to the mansion, Lana is surprised to learn the true identity of the stalker.

Tobias, a young man who was blinded in the last meteor shower, is being used to identify kryptonite-enhanced individuals so that LuthorCorp can place tracking devices in all of them. Unaware of what is really happening, he identifies Chloe as being kryptonite-infected. Fearing what she will become, Clark promises to look after her and any potential power she may develop.

Lana begins having second thoughts about her marriage to Lex, and finally decides to find out the truth about Clark. After learning the truth, by way of deception, Lana promises Clark that she isn't going to marry Lex. Lionel realizes what is going on and forces Lana to walk down the aisle. Clark, unaware that Lana knows the truth, is stunned when she marries Lex.

Since Lana's wedding, Clark has devoted himself to bringing wanted criminals to justice, by any means necessary. Getting a tip from Oliver, Clark learns about an underground fighting ring where Titan, an escaped Phantom Zone criminal, has taken up fighting krypto-warriors. Clark joins the fighting ring to take on Titan. Lana suffers a miscarriage, and Lex destroys all evidence of her pregnancy.

Chloe's mother wakes from her catatonic state with some help from Lex, who is interested in her ability to control meteor-enhanced people. Moira Sullivan quickly begins controlling Chloe in an effort to break out of Lex's facility. With some help from Clark, she is able to see her daughter again, but without Lex's drugs, she slips back into catatonia. Lana learns the truth about her pregnancy: she was never pregnant at all.

The wife of special forces soldier Wes Keenan kidnaps Lex in an effort to get her husband back from LuthorCorp and hides him in an abandoned tunnel system with bombs planted throughout. Lionel convinces Clark to go in after Lex. With the walls lined with kryptonite, and only a short time before everything collapses, Clark and Lex are forced to work together to escape the tunnels.

Jimmy is knocked unconscious and dreams he's a reporter for the Daily Planet in 1940. In the present, Chloe and Jimmy try to figure out who shot Lana, but it's Lois and Lionel who discover that Lex is working with Senator Burke on a project called Ares. Chloe learns that Lionel forced Lana to marry Lex, and that he's using her to spy on Lex.

Lex uses the DNA from meteor-infected individuals, and that of Titan, to turn Wes Keenan into a super soldier. Wes' first mission is to kill Senator Burke, who has threatened to expose Lex's operation. Clark battles Wes, and defeats him using his heat vision. Martha takes a job in Washington, D.C.

Clark tells Lana the truth about his origins, and learns that Lionel forced her to marry Lex. Martian Manhunter reveals Lionel is working as an emissary for Jor-El. Lois discovers Lex's research facility. When she is fatally wounded, Chloe sacrifices herself to save Lois' life. Lana tries to leave Smallville, but is caught in a car bomb; Lex is arrested for her murder. The last phantom copies Clark's DNA, and becomes a bizarre version of Clark.

Clark confronts a bizarre version of himself and the ensuing fight causes Reeves Dam to burst. Lex, who was arrested for Lana's murder, is caught in the flood of water. Before he can drown, Lex is saved by an unknown girl who he later believes to be an angel giving him a second chance at redemption. Lionel's body is taken by an unknown person. Chloe is pronounced dead at the hospital, but she resurrects herself in the morgue. Clark discovers his doppelgänger's weakness, the yellow sun, and exploits it with the help of John Jones (Phil Morris). Lana is revealed to be alive and living in Shanghai, China.

Clark discovers he has a cousin, Kara, who was stuck in suspended animation for eighteen years. After a rocky first meeting, where Clark and Kara fight, the two soon band together to find Kara's stolen ship. Together they find her ship, which was taken by the Department of Domestic Security, but it is in self-destruct mode. Kara absorbs the explosion before it can kill anyone. Later, Kara reveals that a Kryptonian crystal, hidden inside the ship, was stolen before the ship exploded. Lex finds Lana, who used a LuthorCorp clone of herself to help fake her own death, in China. Lex returns to Smallville, determined to find the girl—Kara—who saved his life.

Kara decides she wants to join the Miss Sweet Corn Pageant. Clark tries to teach Kara to control her abilities, so she does not expose their secrets, but gets frustrated with her lack of concentration. Lana returns to Smallville, with all legal charges dropped against her, and reunites with Clark. Tyler and Tempest, two meteor-infected pageant contestants who witness Kara using her abilities, convince Kara to help them steal some buried treasure. The treasure turns out to be an SOS alert from another Kryptonian on Earth. Lex confronts Kara and promises to find out the truth of her abilities.

Chloe learns that Dr. Curtis Knox (Dean Cain) has a surgical cure for those affected by kryptonite, so she sets up an appointment, knowing a side effect could be memory loss. Knox turns out to be an immortal serial killer, and also turns out to be Jack the Ripper. John Jones shows up at the Kent home and warns Clark that he cannot trust Kara. John explains that her father, Zor-El, attempted to assassinate Clark's father. Clark is told to find Kara's crystal before she does, but he is side-tracked fighting Knox, who is attempting to take Chloe's heart and transplant it into the woman he loves. Lana uses the $10 million she stole from Lex to buy surveillance equipment to spy on him.

While filming takes place on the Warrior Angel movie on the Kent farm, Clark saves lead actress Rachel Davenport (Christina Milian) from a car crash. After some researching by Chloe, it is discovered that someone is trying to kill Rachel, because they believe her character should die, like she does in the comics. Clark's secret is uncovered by the attacker when he is witnessed stopping a bullet intended for Rachel; he attempts to kill Lana in hopes that her death will make Clark see his true destiny as Earth's savior. Lana is revealed to be the one who kidnapped Lionel Luthor, and when he is finally freed, Lionel informs Lana that he knows she kidnapped him.

Clark learns that Kara is in Washington, D.C. looking for the crystal from her ship. Kara learns the exact location of the crystal, but it is not there when she arrives. Clark confronts her in a club, but she flies away. With Jimmy's help, Kara follows a path to Lex's mansion, but Agent Carter is waiting. Using kryptonite handcuffs, Carter takes Kara back to Virginia. Using a kryptonite truth serum, Carter attempts to learn about Krypton, but Clark interrupts him and saves Kara with Lionel's help. Clark shows Lana that he has Kara's crystal, which contains his birth mother's DNA.

Lightning strikes a windmill on the Kent farm while Clark is weakened by nearby kryptonite; the bolt travels through him and Lana, transferring a portion of his powers to her. After sharing their first intimate moment in two years, Clark begins to worry about Lana's use of the powers after remembering what happened to Eric Summers and Jonathan Kent when they were imbued with Clark's powers. Lana becomes more aggressive with the powers, stealing confidential files from Lex—which show that Lex has been keeping what remains of Milton Fine's ship—and later attacking him. After a battle with Clark, Lana's powers are reabsorbed when Clark uses a high voltage shock and kryptonite to take the powers back; during the fight, Fine's remains are released.

Clark uses Kara's crystal to resurrect his mother Lara, but unknowingly brings Zor-El back. Lara unwittingly gives Clark a blue kryptonite ring that strips his powers, while Zor-El tries to take over the world. Lois and Grant's romantic relationship is discovered by Lex and Chloe. Grant and Lex are revealed to be working together, and Grant is revealed to be Lex's younger brother Julian Luthor. Clark gets to the Fortress and shatters the crystal, which destroys Zor-El and Lara. Kara is transported to Detroit, Michigan, with no memory of who she is, and Jor-El informs Clark there will be consequences for his repeated defiance.

Clark and Lana team up to take down Lex, and discover, through an Isis Foundation patient, that Milton Fine is still alive. Adrian, one of Lex's experimental patients, plants a bomb on Chloe, threatening to kill her if Lois does not get Lex to admit that he is cloning humans. Lois confronts Lex, and, after Lois is knocked unconscious by Lex, it's revealed that the patient is a failed clone of Lex's brother Julian. Adrian also reveals that Grant Gabriel is the successful clone. Chloe, fearing that she will die, confesses to Jimmy that she was infected by the meteor rocks. In the end, it is revealed that Bizarro has been posing as Clark the entire time, unknown to anyone else, with Clark trapped at the Fortress of Solitude.

Lana is unaware that Bizarro is impersonating Clark, who is still frozen at the Fortress of Solitude, and reveals information about Milton Fine to him. Bizarro tracks down Fine in the hope that he will help him combat his yellow sun weakness. Fine directs Bizarro to Dax-Ur, a Kryptonian scientist who came to Earth years earlier. Jor-El releases Clark from his imprisonment so he can defeat Bizarro. Clark receives blue kryptonite from Dax-Ur and uses it to destroy Bizarro. Clark unwittingly leads Fine to Dax-Ur, who uses Dax-Ur to restore his powers. After Grant reveals his true identity to Lionel, Lex has him killed.

Chloe intercepts confidential information from Lex, but the Black Canary shows up and steals the information back for Lex. When Lex learns the Green Arrow was involved, he sends Black Canary after him. Black Canary attacks Oliver, believing him to be a terrorist, and in the process reveals his secret identity to Lois. Clark confronts the Canary, and convinces her of the truth. Oliver offers Black Canary a spot on his team and she accepts, while Clark and Lana try to reconcile their relationship.

Lois discovers that Lex has found Kara, who is suffering from amnesia, and follows him to Detroit after her. The busboy at the diner that Kara works is obsessed with her, and when Lex arrives, the busboy shoots him, fearing that he will take Kara away. He then holds Kara and Lois hostage. Clark, in efforts to find them, enters Lex's mind using experimental LuthorCorp technology; here he discovers Lex's good side, child Alexander, is still alive. Chloe uses her powers to bring Lex back from the dead, leading to a personal struggle with the moral aspect of her powers.

Pete Ross (Sam Jones III) chews some kryptonite-laced gum and develops the ability to stretch his body to extreme lengths, which he uses to save Kara's life from a falling speaker at a OneRepublic concert in an abandoned warehouse. Pete arrives at the Kent farm and gets up to speed on who knows Clark's secret, before revealing his own power to Clark. Pete decides to reveal his ability to the world, against Clark and Chloe's advice, but Lex blackmails him into stealing Kara's bracelet from Lionel's safe. When Pete does not deliver, Lex tortures him; Clark arrives and saves Pete. Kara, no longer trusting Clark and Lana, stays with Lex, while Clark secretly hides the bracelet.

Lionel hires a group of men to kidnap Clark, using kryptonite tazers to subdue him, and lock him in a kryptonite-lined cell. Patricia Swann (Gina Holden), Dr. Virgil Swann's daughter, comes looking for the Last Son of Krypton and accuses Lionel of taking the Last Son for himself, and having a hand in the deaths of her father, the Teagues and the Queens – three families who came together with Lionel, under a secret societal name of Veritas, to welcome the Last Son to Earth. Chloe and Lana discover Lionel's actions, so they take Kara to Jor-El, who restores her memory; with her powers returned, Kara saves Clark. Patricia Swann gives Clark her father's journal; later, Lex has Patricia killed and a pendant she was wearing—which depicted the Veritas symbol—delivered to him.

Brainiac propositions Kara at the farm, but she refuses; Brainiac warns Kara, and Clark, that not working with him will cause people to get hurt. Jimmy and Lois work together to uncover the truth behind Patricia Swann's murder. Lex begins searching for the secret of Veritas with a key he found in Patricia's pendant. Kara attempts to teach Clark to fly, but he is more focused on finding Brainiac, who attacks Lana at the Isis Foundation. In order to save Lana's life, Kara agrees to help Brainiac. Lana is placed in a clinic, stuck in a catatonic state, while Clark and Chloe have no leads as to where Brainiac and Kara are.

Lex takes Lionel's locket, which holds the second key to the deposit box in Zürich, and then throws him out the LuthorCorp window to his death. Lex soon discovers the key is not where he thought, and heads to the Daily Planet to find it; he also begins having hallucinations of his younger self. Lex finds the key in Chloe's desk, and then fires her. Jimmy and Lois discover that Lionel was murdered. Clark confronts Lex at the mansion, informing him that he has proof Lex murdered Lionel. Lex's assistant destroys the evidence, and discovers Clark's secret. Before she can tell Lex everything, a mysterious stranger kills her.

In order to locate Brainiac and Kara, Clark has Chloe hack into government satellites. The Department of Domestic Security has been monitoring Chloe's activity and, convinced she is a terrorist, convince Jimmy to work with them to bring her down. Clark decides to head to the Fortress to find a way to save Lana, where he learns that Kara is at Krypton trying to warn Clark that Brainiac intends to kill the infant version of Kal-El. The Feds have Jimmy accompany Chloe to a club, which is a front for a security building, to find out who her target is. The Feds catch Chloe stealing satellite images and begin interrogating her. Jimmy shows up and saves her life, and agrees to do whatever Lex wants in exchange for clearing Chloe's name with the government.

Jor-El sends Clark to an alternate reality to show him what the world would be like if he never arrived on Earth. Here, the Kents have a natural-born son, Chloe is engaged, Lana married a french philanthropist, Lois is a Pulitzer Prize–winning journalist, Kara is the head of the Department of Domestic Security (DDS) using the alias Linda Danvers, and Lex is the President of the United States. In this reality, Clark is unable to prevent Brainiac and Lex from detonating the country's nuclear missiles. After learning the world needs him, Clark is sent to Krypton to prevent Brainiac from killing him as an infant. After stopping Brainiac, Clark and Kara both return to present day Earth.

The bank teller from Zurich attacks Lex, carving the Kryptonian symbols for Traveler, Savior, and Sanctuary into his chest. After seeing the symbols, Clark travels to Montreal, Quebec, where he finds Edward Teague (Robert Picardo), Jason Teague's father, the only surviving member of Veritas. Edward deems that Clark is no savior and attempts to kill him so that Lex cannot control him. Chloe saves Clark, who in turn saves Edward from Lex, who arrived looking for more clues to controlling the Traveler. Lex returns home and discovers an orb hidden inside the mantle above the fireplace. The orb gives the location of the Fortress of Solitude.

Kara informs Lex that he will defeat the Traveler, who is really destined to destroy mankind, and sends him to the Fortress of Solitude. Clark learns that Brainiac has been impersonating Kara, who is actually stuck in the Phantom Zone, and destroys him to finally free Lana from her comatose state. Lana leaves Clark a DVD stating that she is holding Clark back, and the only way for him to help the world is if the two of them are not together. The DDS arrest Chloe just as Jimmy is about to propose marriage; Jimmy goes to Clark and tells him about the deal he made with Lex, also informing him that Lex is headed to the Arctic. Clark arrives at the Fortress just as Lex, who now knows Clark's secret, places the orb onto the crystal control panel, bringing the Fortress down around him and Clark.

After the collapse of the Fortress of Solitude, Oliver Queen, Arthur Curry, and Dinah Lance set out searching for Clark. At the same time, newly promoted Tess Mercer also begins searching for Lex Luthor. Oliver discovers that Clark is being held captive in Russia, and leaves to rescue him. Chloe is revealed to be in the custody of LuthorCorp, who have been testing her developing powers, which now include super-intelligence. Lex's assistant, Regan, has been using Chloe to locate the members of Oliver's team. Oliver and Clark, who has lost his powers, arrive at the LuthorCorp site and rescue Chloe, Arthur and Dinah. John Jones arrives and restores Clark's powers, at the cost of his own. Afterward, Clark decides that he must leave the farm and pursue a new life, one that is free from the things that have been holding him back from his destiny. Clark starts his internship in the Daily Planet with Lois as his co-worker.

On Clark's first day at the Daily Planet a bomb on a bus goes off outside the building. Chloe helps one of the injured passengers, Bette, and meets paramedic Davis Bloome. Bette, a homeless teenager, stays with Chloe while Davis contacts a friend who runs a shelter for the homeless. Clark discovers that there was no bomb on the bus, but that someone blew it up with their meteor power. Clark and Lois deduce that Bette is the one with the meteor power, and Clark arrives at the Talon to save Chloe before Bette can hurt her. As Bette heads to Belle Reve, Tess stops by and persuades her to join a group of individuals, who also have meteor powers, that Tess has been forming.

Oliver collapses at a fundraiser and reveals to Clark and Chloe that he has been poisoned and only has twelve hours to live. Chloe calls Davis, who attempts to find a cure for Oliver's ailment, while Clark tries to find out who is responsible. Tess assigns Lois the job of uncovering the truth about Oliver's drunken fall at the fundraiser. While unconscious, Oliver relives the time he was shipwrecked on an island and how he first learned to shoot a bow. He also relives his first meeting with Tess, who was kidnapped while doing marine research in Fiji by a man named Marcos. Clark manages to get an antidote for Oliver, who informs him that Tess will be attacked next. Clark saves Tess before Marcos, who has returned, can kill her. Tess later takes revenge and poisons Marcos before sending him to the hospital to die.

Tess and a scientist activate the crystal that built the Fortress of Solitude, which results in an energy beam being sent into space. An alien, Maxima, from the planet Almerac recognizes the beacon as Kryptonian and comes to Earth to search for the Kryptonian she believes sent for her. Maxima tracks the signal to Tess, and then mistakenly identifies Jimmy as the Kryptonian. Maxima's kiss almost kills Jimmy, but Clark comes to the rescue. Maxima realizing Clark is the Kryptonian she has been looking for, finds Clark at the Daily Planet and she uses her hormone-enhanced kiss to take control over Clark. When Clark tries to comfort Lois, who witnesses the pair kissing, Maxima assumes she is a rival mate and attempts to kill her. Clark stops Maxima and uses her bracelet to send her back to her home planet; he also learns that Tess has his crystal.

Chloe and Jimmy are kidnapped after their engagement party by a jeweler who wants to test their love. Using a lie-detector to quiz them, every time one is caught in a lie the other is punished with a surge of electricity. Clark and Lois discover that they are missing and pose as a couple to lure the kidnapper out of hiding. Chloe and Jimmy survive, answering the questions to the jeweler's satisfaction, who sets them free; unfortunately, Lois is kidnapped by the jeweler. Clark goes to her rescue, but a kryptonite watch the jeweler wears weakens Clark. During the line of questions, Lois admits that she loves Clark. Before Clark can answer, he manages to strip the watch off the jeweler and then knock him unconscious. Later, Lois chalks up her love for Clark as nothing more than a lie, which she was able to accomplish by slipping the lie-detector electrode off her finger.

A serial killer attacks a local club, injuring and murdering several patrons. Clark arrives and discovers Davis's body, covered in blood and lying unconscious on the floor. Davis denies any memory of the event. While looking for clues, Clark meets John Jones, who, since losing his powers, has taken a job as a police detective. John and Clark work together on the attack, with John indicating that there have been others and that Davis has been the first to arrive on each of the scenes. Davis discovers that the blood on his body is not his, and that he has no wounds; Davis starts to believe that he is the killer because he suffers blackouts during the attacks, and finds his skin under the fingernail of a victim. One of Chloe's Isis clients attacks Davis and Jimmy, and after Clark subdues him, the client confesses to all of the murders. John warns Clark that his heroic actions are getting a lot of attention and could expose him to the world, so he needs to be more careful when saving people.

Lois and Jimmy are mugged on the street, and when Jimmy attempts to snap a picture of the mugger he catches a blurred image of Clark saving Lois. Jimmy goes on the hunt to identify the mysterious Good Samaritan, and Chloe tells Clark that he should use this opportunity to create an alter ego for himself like Oliver has with Green Arrow. Tess plants a new reporter, Sebastian Kane, at the Daily Planet, who has the ability to steal memories, to find out if Lois stole the crystal. Jimmy's research leads him right to Clark. Having Oliver pose as the Good Samaritan, Clark sets up a scheme and shows Jimmy that he is wrong. Sebastian attempts to kill Lois after discovering that she knows who he is, but Clark intervenes. Chloe visits Sebastian, and when she learns that he knows Clark's secret she uses her abilities to give him a stroke.

Someone sends Clark the crystal to rebuild the Fortress, only, when Clark touches the crystal it activates and sends him and Lois to the Phantom Zone. There, Clark and Lois find Kara, who helps Lois escape back to Earth. Unfortunately, General Zod's wife, Faora, also escapes and takes over Lois's body. Faora sets out to find her son, who turns out to be Davis – Faora explains that he was created when Faora and Zod could not have children. Chloe uses her powers to bring Clark and Kara back to Earth, with Kara getting John Jones's crystal to exorcise Faora from Lois's body. Tess pieces together that Clark was in the Arctic with Lex when he disappeared, while Kara decides to leave Earth in search of Kandor, a city that could possibly house survivors of Krypton.

Chloe's memories begin rapidly disappearing, as Brainiac replaces them with Kryptonian code, with the symbol for Doom appearing repeatedly. After Chloe forgets everyone, except Davis, Clark decides he has to use the crystal to rebuild the Fortress of Solitude and have Jor-El restore her memories. However, Clark makes a sole provision, that all of Chloe's knowledge about Clark's true identity be removed. As Jor-El restores her memories, Brainiac leaves Chloe and infects the Fortress, unknown to Clark. With her memories restored, Chloe continues planning her wedding with Jimmy. Davis visits Chloe and confesses his love for her, and that he believes she is marrying the wrong man.

While Lois organizes Jimmy and Chloe's wedding, Oliver shows up on the Kent farm and informs Clark that Lex is still alive, but he needs Clark's help to find Lex's exact location. Clark declines his immediate assistance, explaining that Chloe no longer knows his secret and would never understand why he could not give her away at her wedding. Traveling to Cuba, Oliver meets Lana Lang, who has also been following Lex's trail. Oliver convinces Lana to come back to Smallville, and she arrives at the wedding interrupting Clark and Lois just as they are about to kiss. A security guard discovers Davis disposing of evidence, but before he can call the police, Davis morphs into a Kryptonian monster and kills him. The monster arrives at the ceremony, where he critically injures Jimmy and kidnaps Chloe; he then takes Chloe to the Fortress of Solitude. Lois decides to leave Smallville to help Jimmy although her real reason is the arrival of Lana and leaves heartbroken.

Clark is attacked by the Persuader in his barn, but before he is killed a trio of superpowered aliens from the 31st Century, called the Legion, shows up and saves him. While inhabiting Chloe's body, Brainiac informs Davis that he will soon become the creature Doomsday permanently, and places him in an ice cocoon for the metamorphosis. Rokk, Imra and Garth inform Clark that today is the day he is supposed to destroy Brainiac for good, but the only way for him to do that would be to kill Chloe. Brainiac begins sucking the knowledge from every human mind through the world's computer network when he is attacked by the Legion. Before the Legionnaires can kill Chloe, Clark intervenes and convinces them to focus their powers and pull Brainiac out of Chloe. Afterward, the Legion takes what is left of Brainiac with them back to the future to reprogram him into Brainiac 5, leaving Clark with a Legion ring of his own.

John Jones is shot by an unseen assailant while on duty, and Chloe and Clark suspect that the shooter was another police officer. Clark goes undercover as a cop to identify the shooter. Clark discovers that a group of officers are taking the law into their own hands, and killing criminals. The group realize who Clark really is, and frame him for John's attempted murder. Believing that Green Arrow is on to them, the cops attempt to kill him as well. Luckily, Clark's words of encouragement persuade one of the cops, a young Dan Turpin, to turn on the others. With some help from John, who has recovered, Clark is cleared of all charges. Lana informs Tess that Lex inserted a nano-transmitter into her optic nerve so that he could keep an eye on everything she was doing. As retribution, Tess offers Oliver the chance to buy LuthorCorp.

Believing that Lana has been kidnapped, Tess tells Clark that she believes Lex took her. She also informs Clark that the reason Lana left after coming out of her coma was because Lex had her taken into custody when she woke, and forced her to break up with Clark via a video. After Clark talks with Chloe, he realizes that Lana never returned because she was busy plotting her revenge against Lex. Clark and Chloe discover that Lana was not kidnapped, but intends to use Lex's Prometheus technology, which harnesses alien DNA to give an individual super-human abilities, on herself. It is a success, and Lana is imbued with super-powers of her own. Later, she tells Clark that he no longer has to worry about her, and that they can work together to make the world a better place.

Just as Oliver is announcing to the LuthorCorp board of executives that Queen Industries has bought controlling interest in LuthorCorp a bomb detonates in the meeting room. Clark and Lana investigate the bombing and discover that the bomb was made with kryptonite. Lana also discovers that her suit not only gives her strength and speed, but absorbs kryptonite radiation as well. The bombmaker, Winslow Schott, a former Queen Industries employee now under the employ of Lex, plants another bomb on the roof of the Daily Planet. When Lana absorbs the kryptonite in this bomb to deactivate it, she becomes so irradiated that she and Clark can never again be near each other. Clark tracks Lex down, but Lana stops him from doing something he would regret, and Lex's mobile safe-house explodes and kills him. To keep from harming Clark, Lana leaves Smallville, again.

Lois Lane returns to Smallville and is not happy to see Clark. Linda Lake comes back and threatens to expose Clark's secret if he does not agree to provide her with the inside scoop on all of the Red-Blue Blur heroics he performs. Instead, Clark has Lois write his story as a means of controlling the inevitable. In response, Linda announces that Clark is part of an alien invasion, and that he killed Lex Luthor. With the police after him, Clark uses his Legion ring to go back in time and stops Linda from writing her story; Clark destroys the ring afterward. Davis begins taking antipsychotic medication to keep his alien side from coming out. When Linda tries to bring out Doomsday, in an effort to escape from going to prison, Davis keeps the creature from coming by killing her.

Clark begins to embrace the idea of a double identity by wearing his blue shirt under his suit, carrying his red jacket in his backpack, and switching into his Red-Blue Blur persona whenever he needs to. Tess orchestrates an elaborate plan to expose Clark's secret, which involves stranding the two of them on a plane on the verge of crashing. Clark manages to get the two to safety without Tess seeing him use his powers. Meanwhile, Jimmy witnesses Davis murdering a man in the hospital, but Davis drugs Jimmy with a hallucinogen to make it appear that he is delusional. After witnessing Chloe and Davis hugging, and having Chloe stun him with a taser before he could hit Davis with a pipe, Jimmy informs Chloe that marrying her was a mistake and he walks out on her.

A magician, Zatanna, grants Chloe's wish to have Lois's life, and as a result Chloe wakes up with Lois's body. Chloe informs Clark about what has happened, and the pair track down Zatanna. Chloe learns that to reverse the spell she has to not want the wish any longer; at the same time, Clark inadvertently wishes to have a normal life, which deprives him of the knowledge of his abilities. Zatanna visits Oliver and offers to grant him one wish if he can find her father's book of spells. Oliver gets the book, and Zatanna sets out to resurrect her father with it, which will require her to sacrifice her own life. Clark regains the memory of his alien heritage with help from Chloe, and convinces Zatanna not to sacrifice herself but instead use her gifts to honor her father's memory.

After doing some research, Tess informs Davis that he crash landed to Earth in 1989, during the Smallville meteor shower, alongside another boy. She tells Davis that he and Clark Kent are destined to fight and kill each other, and that Clark cannot accept his role as Earth's savior until he kills Davis. Davis remembers that he was hurt by kryptonite as a child, and has Chloe lock him in a tank and drown him in a kryptonite solution until he dies. Tess tries to convince Clark that she knows who he is, and her theory about his needing to kill Davis, but she fails. In the end, Davis returns to life and is now immune to kryptonite; he informs Chloe that her presence is the only thing that keeps Doomsday at bay. It is also revealed that Tess is in possession of the Kryptonian orb that took Clark's powers.

After saving Chloe from a carjacker, who turns out to be local mobster, Bruno Mannheim, Lois takes on the superhero persona of Stiletto, which she uses to get closer to the Red-Blue Blur and convince him to give an interview to Lois Lane. Jimmy is enlisted to take photos of Lois in her Stiletto costume, but his camera is taken by the mobster, who wants revenge on Stiletto. Clark goes looking for Stiletto, in an effort to track down Chloe's laptop that contains files on Oliver and his team, and discovers that Lois is Stiletto. After lecturing her on faking a story, he tracks down the laptop but is incapacitated by kryptonite. Lois arrives just in time to save Clark. In the end, Lois receives a call from the Red-Blue Blur who informs her that she does not need to fake stories to be a good reporter, and when he is ready to come out to the world she will be the first to know.

Clark begins to suspect that Davis is alive, and when the Metropolis police issue a manhunt for Davis, whom they believe to be a local serial killer, Chloe decides it would be best if they both just left Smallville. Clark informs Chloe that he can send Davis to the Phantom Zone using the crystal from the Fortress of Solitude; hearing this, Chloe lies and tells Clark she thinks Davis could be in Alaska. Clark finds Davis in the process of killing Oliver, but he intervenes and takes Davis to the Fortress. Clark uses the crystal to open the Phantom Zone, but Chloe arrives, removes the crystal, and chastises Clark for giving up on Davis. Chloe and Davis leave the Fortress and Smallville, going off the grid so that Clark and Oliver can not track them.

Tess gathers a team of meteor-infected individuals to track Doomsday so that she can give Clark his location, and hopefully convince him to kill Doomsday. One of Tess' team members pretends to be Chloe in order to trick Clark into killing Doomsday. Instead, Tess learns that Clark plans to use black kryptonite to split Davis from his Doomsday persona, and send the beast into the Phantom Zone. As a result, Tess steals the crystal that opens the Phantom Zone and destroys it, all at the request from a disembodied voice claiming to be from Kandor that emanates from the Kryptonian orb she has. Tess informs Clark that now he has no choice but to kill Doomsday. Meanwhile, Oliver confesses to Clark that he killed Lex, which forces Clark to question who Oliver has become if he's willing to take another man's life.

Rokk returns from the 31st Century and informs Clark that Doomsday will kill him, and gives him a new Legion ring to transport Doomsday to the future. Instead, Clark decides to use black kryptonite to split Davis from Doomsday, and bury the beast a mile underground. Tess confronts Lois about stealing the Kryptonian orb, but as the two fight, Lois finds the Legion ring and is transported to another time in history. When Davis starts to change, Chloe uses the black kryptonite to split him herself. Clark battles Doomsday in the streets of Metropolis and manages to bury Doomsday, as planned, using explosives to seal the tunnel. Davis stabs Jimmy when he realizes that Chloe still loves Jimmy, but before he dies Jimmy impales Davis on a metal rod. Clark tells Chloe that it is human-learned emotions that have caused him the most trouble, and vows that Clark Kent is dead; the orb returns to Tess and releases Zod.

Lois returns from the future with no memory of the three weeks she is missing. Meanwhile, Clark has been training with Jor-El, while also branding his family crest around Metropolis after saving someone. After saving Lois, Clark's feelings for her cause a disruption in his training and he realizes that the only way to finish is if he tells Lois goodbye. Dr. Emil Hamilton and Chloe begin working together in the Watchtower. Released from the black orb, Major Zod's soldiers initially turn on him when he fails to provide answers as to why none of them have the true powers of a Kryptonian like they should. Eventually, Zod regains their trust. A Kandorian woman (Monique Ganderton) from the future returns with Lois in the hope of finding Clark and killing him. When the two meet, the assassin releases blue kryptonite that nullifies hers and Clark's powers. In the battle the assassin is accidentally killed when she impales herself but not before revealing that Clark will cause the destruction of Earth. Just as she is falling asleep, Lois has sporadic visions of future events.

Daily Planet reporter John Corben (Brian Austin Green) is hit by a truck while trying to ascertain the Blur's identity. When he wakes up, John discovers that his body has been outfitted with robotic parts, and his heart replaced with a piece of kryptonite that acts as a power source for his body. Tess later discovers that Zod and his men were the ones who helped John, but only as a means to test a new way for them to get their powers. While helping the Blur, Lois is kidnapped by John as a means of drawing the Blur out. Clark arrives and fuses a lead plate to John's chest with his heat vision to protect himself from the kryptonite. When John pulls the plate off it removes the kryptonite and shuts down John's vitals. Clark and Chloe realize that Tess is after Lois's memories, so it is decided that Clark must return to society so that he can keep Tess from learning that he will be the cause of Earth's destruction.

After Tess is admitted to the hospital showing zombie-like symptoms, Clark has Dr. Hamilton investigate the cause with a Disease Control specialist. Clark overhears that Tess was at the Daily Planet when she began to show symptoms, so he speeds to the Planet to rescue Lois. In a battle with multiple zombie attackers, Lois is bitten. Clark then volunteers his blood to Dr. Hamilton, who discovers that the virus was created from Kryptonian enzymes, so the doctor can create a cure. With Chloe's help, Dr. Hamilton manufactures a rainstorm and seeds the clouds with the cure to create maximum coverage. It is revealed that the virus was used as a ploy to draw out the Blur, as one of Zod's men realizes that he was also Kryptonian. Based on the House of El symbol the Blur brands around town, Zod believes that Jor-El is on Earth, and has harnessed the power from the yellow Sun for himself. Oliver decides to burn his Green Arrow outfit, and give up trying to be a superhero.

Jor-El gives Clark the ability to hear others' thoughts in an effort to teach Clark to hone his Kryptonian intuition and learn to not allow humanistic assumptions inhibit his destiny. While using this new ability to determine who blew up a Queen Industries textile factory, Clark also learns more about Lois's feelings for him and asks her out on a date. Clark has to stand Lois up when he learns that the Toyman has returned to get revenge on Oliver. Jor-El takes back the new ability, forcing Clark to use the instincts he has gained. At a company gala, Toyman informs Oliver that there is a bomb directly under the podium, and that he will kill everyone if Oliver does not confess to killing Lex. Clark locates the real bomb before Oliver can take his own life with it to pay for the sins he feels he committed. Toyman is caught, and Tess gives him John Corben's kryptonite-powered heart so he can tell her how it works.

At a casino, Oliver meets a woman named Victoria, who goes by the name Roulette and gives him a red pill to swallow. Afterward, Oliver passes out and wakes up trapped inside a coffin. After breaking out, Oliver finds himself in the middle of someone else's deadly game designed to make him pay for destroying someone. Oliver finds Roulette in the casino, but the two go on the run when the people behind the game show up. While escaping, Victoria is shot and killed and Oliver is arrested. Eventually, with Chloe and Clark's help, Oliver comes to the conclusion that Roulette created the game to distract Oliver long enough to empty the $3 billion he had in his bank account. In reality, Chloe orchestrated the entire event to get Oliver to realize that he is still the hero he once was. In addition, Clark discovers that there are other Kryptonians on Earth.

While Lois and Clark prepare to host a new morning talk show, Oliver attempts to train a prostitute/cage fighter, Mia Dearden, to be mentally stronger after witnessing her battle with her own personal demons just as he did. In addition, Tess unknowingly builds a solar powered energy plant that will allow Zod the chance to harness the powers of the Sun for his own machinations. Later, Zod tells Tess to locate the Blur for him. Oliver confesses to Lois that he still loves her—while Clark witnesses from a video camera—but she acknowledges that she wants Clark and not him. Mia betrays Oliver to her pimp, who kidnaps and tries to rob him; Clark overhears the fight and manages to save everyone. In the end, Oliver gives Mia a second chance and Clark shows Lois his true feelings when he kisses her.

Zod recalls to his troops how twenty years before the destruction of Krypton the Ruling Council took their blood shortly before the destruction of Kandor, which is what was used to clone each of them on Earth. Just as Clark realizes that his father is on Earth while investigating a Kandorian landing in the desert, Jor-El arrives at the Kent Farm. Chloe finds Jor-El at the farm and fills him in on the man his son has become, as well as the revelation that Zod—who was once Jor-El's best friend—was responsible for Krypton's destruction. After kidnapping Jor-El, Zod discovers that Jor-El's son is on Earth, and that he is the Blur. Zod releases Jor-El, mortally wounded, who unknowingly leads Zod to Clark. As his dying wish, Jor-El requests that Clark save Zod from whom he will one day become.

In an attempt to fuel the legend of the Blur, twins Jayna and Zan — who have the ability to morph into animals and water-based forms, respectively—begin performing saves around Metropolis and painting Clark's shield at the scene of the crime. Unfortunately, mistakes made by the twins push the Blur under scrutiny from the District Attorney, who challenges the Blur to reveal himself. Meanwhile, Lois accidentally hears Clark's voice while talking to the Blur, and goes out of her way to convince the citizens that it is best if the Blur does not reveal himself. With help from the twins and Chloe, Lois is convinced that Clark and the Blur are not the same person. Clark encourages the twins to continue using their powers to help others, but to be more careful. Clark confesses to Lois that his big secret is that he is near-sighted, pulling out a pair of glasses. Lois responds by kissing Clark, but visions of the future send her into a seizure.

Tess kidnaps Lois and uses a memory reading machine from Sommerholt Institute to try to discover Lois's lost memories. In order to see how Zod saves humanity, Tess synchronizes her brain with Lois's so that she can live through the memories. In the future, the solar powered energy plant LuthorCorp builds is used to harness the solar radiation from the Sun—turning it red and stripping Clark of his powers—and provide Zod and his troops with all of their natural powers. Clark discovers that Tess has Lois, but when he attempts to remove Lois from the machine he inadvertently syncs his own brain to hers. Through Lois's memories, Clark realizes that when he decided to fight Zod he pushed Zod down the road that led to Zod's tyranny over Earth. As a result, Clark decides to follow his father's dying wish and save Zod from himself by befriending him. In addition, he and Lois decide to start dating.

After a date with Clark, Lois is shot with an arrow by a man dressed as the Green Arrow. Later, Chloe is attacked by the same individual. Oliver begins investigating and discovers that an old mentor, named Vordigan (Steve Bacic), is the one behind the attacks. Meanwhile, Zod tells Clark that the Kryptonians are waiting on Clark to help them all get their powers, and that they will resort to anything to get them. Oliver's old mentor kidnaps Mia, Oliver's new apprentice, and uses her as bait to lure Oliver in and force him to kill Vordigen, who believes that he must die at the hands of his own disciple. Instead, Oliver only injures Vordigen and leaves him for the police. After Clark discovers that Zod visited Lois in the hospital, Clark tells him that he will not help the Kryptonians gain their powers and threatens to destroy all of them if they go near Lois again.

After former superhero Sylvester Pemberton—also known as Star-Spangled Kid—is killed by supervillain Icicle, Chloe and Clark begin investigating the murder. The pair discover that Sylvester was part of a group known as the Justice Society of America, which was led by a man named Carter Hall (Michael Shanks), who went by the name Hawkman. They also learn that Carter Hall and the rest of the Justice Society of America have been monitoring Clark and his super hero friends. Another member of the JSA, Dr. Fate (Brent Stait), arrives and informs Clark that he will lead the new generation of superheroes, just as Hawkman led the JSA. After Icicle kills Wesley Dodds, whose code name was Sandman, Hawkman and Sylvester's apprentice, Stargirl, decide to set a trap for Icicle. In the process, Green Arrow interrupts the trap, which causes Hawkman to threaten his life. Oliver calls in John Jones for support, who helps convince Hawkman, Stargirl, and Dr. Fate to work with Green Arrow, Clark, and himself to bring down Icicle. At the same time, Lois receives a package from an organization known as Checkmate, led by Amanda Waller, which leads her to discover the existence of the JSA. Split up into pairs, Dr. Fate saves John from Icicle's attack, sacrificing himself and giving John his powers back at the same time. Banding together, instead of splitting up, Clark, Hawkman, Jones, Stargirl, and Green Arrow defeat Icicle. In the end, Hawkman and Stargirl decide to locate the other members of the JSA, their children, and their protégés to help organize a new generation of superheroes. Icicle is transported back to Agent Waller, who tells him he is part of the Suicide Squad and then shoots him. Afterward, Waller meets with Tess, who is revealed to be another agent of Checkmate.

After stealing an enchanted Warrior Angel comic book, adolescent Alec is transformed into a super-powered adult. With his new abilities, Alec saves Chloe's life. Thinking that Alec, who calls himself Steven Swift, is another superhero, Chloe tries to get to know him and recruit him to Clark and Oliver's super-powered team. At the same time, Zatanna returns and informs Clark that her father was the one who cursed the comic book that turns Alec into Warrior Angel, and enlists his help to track down Alec so that she can reverse the spell. After finding the comic, Zatanna and Clark realize that the story is not about a young boy that becomes a hero, but about becoming a villain. When Chloe attempts to convince Alec to have the curse reversed, Alec turns on her and attempts to throw her off a building. Before he can, Clark saves Chloe and Zatanna reverses the spell, returning Alec back to normal.

Clark is unknowingly exposed to a new form of kryptonite that gives him the power of hypnosis. As a result, Lois quits her job at the Daily Planet and moves in with Clark after he tells her he wants a more traditional relationship. Once Clark finds out about his new power, he goes to Zod to see if he can force Zod to reveal who killed Jor-El. Zod tells Clark that Tess murdered his father, and tries to convince Clark to seek vengeance. After refusing to kill anyone, Clark accidentally hypnotizes himself into seeking revenge and he goes after Tess. Before Clark can kill her, Chloe uses green kryptonite to weaken Clark, which also removes the hypnosis from everyone, including Clark. Zod discovers that one of his soldiers, Alia, killed Jor-El for fear that he would destroy all of the Kandorian clones. As is Kryptonian law, Zod kills Alia for her actions. Clark learns the truth, but still does not trust Zod. As such, Clark destroys the LuthorCorp solar towers, which Zod hoped would bring him powers of his own.

Bernard Chisholm (J. R. Bourne), a doctor who was experimented on by Kandorian scientists, begins kidnapping those same Kandorians in order to expose them to the world. Chisholm tries to persuade Lois to write the story, but when she refuses he kidnaps her and forces her to write it. Clark attempts to locate the missing Kandorians and is confronted by Zod, who knows that Clark destroyed the solar towers. Meanwhile, Oliver discovers that Chloe has been stealing money from his company in order to build kryptonite weapons to use against the Kandorians should they get their powers back. Oliver decides that Clark needs to know, but not until the time is right. Zod locates Chisholm, but he is shot in the stomach during his rescue attempt. Clark arrives and saves Lois and the surviving Kandorian, but watches as Zod dies from massive blood loss. Using his own blood, Clark resurrects Zod. The next day, Zod pretends to make a pact with Clark to help the Kandorians adapt to Earth, but once Clark leaves he reveals that he has gained the powers he was missing thanks to Clark's blood.

Clark and Lois head to a bed and breakfast for the weekend, but when they arrive they find Chloe and Oliver having their own romantic getaway. While settling in, Lois unwittingly releases the spirit of Siobhan McDougal, who was cursed and sent to live in the underworld, from a painting at the bed and breakfast. Known as the Silver Banshee by the villagers, the spirit transfers from one woman to the next, looking to murder any men who come into her path. Eventually, Chloe discovers that destroying the portrait of Siobhan with fire will send the spirit back to the underworld, so she throws the picture into a lit fireplace. Meanwhile, Tess reveals to Zod that she knows he has his powers and also proves to him that she knows his weakness when she opens a box of kryptonite around him. Zod reveals that he is jealous of Clark, as the latter has won the love of the city. Zod, pretending to be The Blur, contacts Lois and requests that she find information on Tess.

Tess and other agents from Checkmate successfully kidnap Green Arrow and transport him to the Checkmate organization. While in transport, Amanda Waller attempts to recruit Green Arrow, unaware that he is billionaire Oliver Queen, to a government cause designed around preparing for a potential alien invasion. Green Arrow declines and escapes. With Oliver still missing, Clark and Chloe begin searching surveillance feeds. John Jones is also investigating and he discovers the location of Checkmate's home base. There, he learns Waller has a sample of Kryptonian blood. Meanwhile, Oliver returns to Metropolis, only to have Tess realize that Oliver is Green Arrow. Tess informs Oliver and Clark that Checkmate has kidnapped Chloe, who was the real target. Clark heads to the Checkmate base and saves Chloe. John Jones destroys the sample of blood, and uses his abilities to erase Waller's memory of Clark, Chloe, and Oliver's faces, preserving their identities. Afterward, Clark tells John that Waller may have been correct about an alien invasion, recalling his vision of the future.

Based on a tip from Zod, who is still posing as the Blur, Lois infiltrates one of Tess's secret labs and discovers she is experimenting with kryptonite. An explosion in the lab sends Lois down an elevator shaft, where she is saved by John Corben. Clark tracks down the lab Lois was investigating, where he is exposed to red kryptonite. Now without any inhibitions, Clark discovers that Chloe and Oliver have been stock piling kryptonite weapons, so he joins forces with Zod, who reveals that he has powers, to seek out and destroy all of them. Afterward, Clark takes Zod to the Fortress of Solitude. Chloe sends John to the Fortress to flush the red kryptonite out of Clark's system by stabbing him with a piece of green kryptonite. John is successful, and using Clark's octagonal key, he teleports himself back to Smallville. When Clark returns to normal he finds Zod has vanished. Later, Zod returns to the Fortress with his troops, using a kryptonite dagger to cut his hand and use his blood to give his troops all of his powers.

The new Daily Planet editor pits Lois and Clark against each other for the right to keep their job, but the pair decide to write the ultimate story on ex-District Attorney Raymond Sacks, whose conviction was overturned. Their story ultimately collapses when the two of them become front page news for fighting at Sacks's Welcome Back party. As a result, the new editor fires both of them. Clark discovers that Lois has been talking to someone posing as the Blur, and when he tries to figure out who is really talking to Lois, the pressure of unmasking the Blur puts a strain on their relationship. Checkmate Agent Maxwell Lord (Gil Bellows) kidnaps Lois and attempts to discover the identity of the Blur by combining the memories of people who have seen glimpses of the Blur into a single, cohesive identity. Clark prevents Lord from completing the image, and Lord's actions bring him face to face with the unidentified Red Queen. As the Blur, Clark calls Lois and tells her they can never talk again, because of the danger their relationship poses to Lois.

Checkmate breaches the Watchtower computer firewalls and begins stealing information. Clark, needing to find Zod, sends Oliver to the Luthor mansion to look through Tess's things to see if he can find any information. At the same time, Clark talks to Faora and reveals to her that Zod has had powers for weeks and that he was the reason Krypton was destroyed. Armed with this new information, Faora attempts to organize the remaining Kandorians to seek out peace with humans, and stand against Zod. Meanwhile, Oliver finds Zod at the mansion and they get in a fight that leaves Oliver with a House of Zod symbol branded on his chest. Checkmate locates the Kandorians and attempts to execute them, but Clark arrives and saves them. Meanwhile, Zod confronts Faora about her betrayal and subsequently kills her; afterward he learns she was pregnant with his child. Zod, now honored with the rank of General, uses Faora's death—he blames it on humans—to bring the rest of the Kandorians to his cause.

Maxwell Lord kidnaps Tess in an effort to find the Book of Rao. Tess escapes only to be caught by the Red Queen, and is forced to give the book to her. Martha returns to Smallville with Perry White, whom she is dating, to the surprise of Clark. Lois informs Clark that they should break up, as she needs to find her true calling in life. Subsequently, Lois and Perry team up on a story about the Book of Rao and the Red Queen that could help Lois regain her job at the Daily Planet. The pair fail to land the story, but a good word to the Editor-in-Chief from Perry allows Lois and Clark to return to the Daily Planet. Meanwhile, Clark discovers that Martha is the Red Queen and asks for the Book of Rao. Martha reluctantly gives him the book, and explains that the book will exile all Kryptonians to another plane of existence, including Clark, and that is why she did not have the original intention of giving Clark the book or revealing her secret identity.

Zod appears to Lois claiming to be The Blur and accusing Clark of trying to reveal Zod's secret. Tess confronts Zod at the Fortress, in an effort to save Clark, but Zod gets the upper hand and uses his heat vision to burn her and leave her for dead before destroying the main console of the Fortress. Clark takes Tess to the hospital, where she tells him there is a second console that will activate the book. Later, Tess is pronounced dead at the hospital. Zod attacks Lois when she discovers he is not the Blur, but Clark saves her and reveals his true identity to her through a kiss. Zod's troops learn of his deceptive actions and agree to follow Clark to their new home through the Book of Rao. Zod uses a blue kryptonite dagger to make him and Clark human, and keep them from ascending. Clark intentionally stabs himself with it and falls off the roof of a building, leaving Zod without its protection and forcing him to ascend with the others off Earth.

Following in the previous season finale, Lois removes the blue kryptonite dagger from Clark's body and hides as he heals. Chloe uses Doctor Fate's helmet to see her future and later swaps herself for Oliver's return from captivity. Tess wakes up healed in Cadmus Labs and discovers Lex Luthor clones. One clone escapes and forces Clark to choose between saving Lois or Metropolis; Clark pushes himself harder than before and saves everyone. Jor-El informs Clark that the darkness within himself will make him Earth's greatest threat, but a vision of his adoptive father Jonathan reminds Clark that he can still be the world's greatest hero. Meanwhile, Lois decides to take the reporting position in Africa and Tess unofficially adopts a child-aged clone of Lex.

Lois takes a Daily Planet field reporter position in Egypt, so Clark sends Carter Hall to look after her. Subsequently, Carter and Lois discuss her running away from Clark in order to protect his secret. Oliver discovers that Chloe erased all records of herself before she disappeared, so he sets out to track her down. He discovers that she traded her life for his, and afterward faked her own death during the interrogation to escape. Back at the Daily Planet, Clark is assigned a new partner, Cat Grant, who hates all superheroes. Meanwhile, the Suicide Squad tags Clark, Oliver, and Carter with special trackers embedded in their skin. Clark decides not to go after Lois in Africa and instead begins wearing a new, red and blue version of his costume.

Radio personality Gordon Godfrey becomes possessed by the dark force Clark was warned about, and begins waging a crusade against all super-heroes. Kara comes back to Earth and tells Clark that Jor-El has sent her to take care of the evil that is coming, as the doubt in Clark's heart will allow it to possess him and use Clark's powers as the ultimate weapon. Lois returns from Africa and learns that Godfrey is planning to reveal Green Arrow's identity, and create doubt all over the world about the super-heroes so that he can manipulate them down a new path. Clark and Kara confront Godfrey, but Kara's Kryptonian bracelet exorcises the entity from Godfrey. Meanwhile, Oliver decides it is best everyone knows the truth, and reveals his identity as Green Arrow.

Clark and Lois attend their five-year high school reunion, which triggers memories of Lana Lang and Chloe. Brainiac 5 arrives from the 31st Century and takes Clark on a journey through his past, present, and future. Brainiac shows Clark that he still blames himself for his adoptive father's death years prior, he is abandoning his friends in the present, and that his fear of his own future is unfounded. After seeing that his future can be exactly how he hopes, Clark returns to the present to support Oliver in his venture to reveal his identity to the world. Later, Clark works to rebuild his relationship with Lois by giving her the attention she deserves, and finally admitting that he loves her.

Clark contemplates telling Lois his secret, while Lois also decides to reveal to Clark that she already knows he is The Blur. Before either can say anything, Lois unwittingly becomes possessed by the Egyptian Goddess Isis, who sets out to resurrect her long lost lover Osiris. Clark and Oliver look to Tess for help in trying to stop Isis, as Osiris's return will unleash Hell on Earth. Clark sets out to stop Isis, but instead almost becomes the vessel for Osiris before Oliver arrives and informs Clark on how to defeat the goddess. Using his heat vision on Isis' amulet, Clark successfully releases Lois from possession. Afterward, Clark and Oliver invite Tess to be part of their team and take over Watchtower. Later, Clark finally tells Lois that he is The Blur.

Clark and Lois get a flat tire in the middle of nowhere, so Clark goes to the nearby town to fix the tire while Lois stays behind. Lois meets a young girl who takes her to a village where the water supply has been contaminated with blue kryptonite. Clark returns to find Lois missing and sets out to look for her. Lois discovers the villagers are planning to sacrifice her to bring continued good crops and health. She and Clark, who is powerless next to the villagers who emit blue kryptonite radiation, are captured. As a result of Lois's intervention, the villagers eventually move far enough from Clark that he superspeeds himself and Lois back to Metropolis where they later make love for the first time. Meanwhile, Tess decides not to stop Alexander's accelerated growth after realizing that he has all of Lex's memories and his evil personality.

General Sam Lane and Lucy Lane, Lois's father and sister, come into town to celebrate Thanksgiving with Lois and Clark. While visiting, the General reveals that he is a proponent of a new vigilante registration law, much to the dismay of Clark and Lois. Tess and Oliver discover that the team is being tracked by Rick Flag, who is reforming the Suicide Squad and has sent out an assassination order for the General. Flag launches a missile to kill the General, but it detonates next to Lois. The Blur saves Lois, which helps to change the General's opinion of some vigilantes. Regardless, the vigilante law passes and Flag begins ordering acts of terrorism on anti-vigilante headquarters.

Lois watches a video tape left by her mother, where Ella Lane (Teri Hatcher) tells Lois not to let the loss of a loved one keep her from living up to her full potential. Subsequently, Lois goes to the Fortress of Solitude and pleads with Jor-El to reconcile with Clark so that Clark can be the hero he needs to be. Meanwhile, Clark helps Tess uncover the truth about a dream Tess had about being in an orphanage. Tess eventually learns she is the illegitimate child of Lionel Luthor, who abandoned her at 5 years of age; her birth name is Lutessa Lena Luthor. Tess was left with Granny Goodness, who turns out to be one of a trinity of prophets for the dark lord Darkseid, the other two being Gordon Godfrey and club owner Desaad.

Oliver registers for the new vigilante registration law, now being overseen by Col. Slade Wilson, in order to protect the rest of the team and find out what the government is planning. Oliver's suspicions are confirmed when the registration location is revealed to be a trap designed to locate and arrest superheroes. Clark teams up with Arthur Curry, now aware of his Atlantean heritage, and Arthur's wife Mera, to track down the superhero prisons the government has built. After the team rescues Oliver, Clark discovers that Slade's actions were influenced by Darkseid. Subsequently, Clark brings Lois onto the team and finally reveals the threat of Darkseid's arrival to everyone.

Clark learns that there is another Lex clone in existence, and that Tess has been keeping him alive behind everyone's back. Clark also discovers that Tess has a Kryptonian box, and when he activates it, it sends him to a parallel universe where Lionel Luthor is his adoptive father and not the Kents. While on the alternate Earth, Clark learns that Tess is actually a Luthor, that his doppelganger goes by the alias Ultraman and murders anyone that gets in his way, including Lex Luthor. Clark acquires the Kryptonian box and manages to send himself back to his own reality, but unknowingly brings Lionel with him.

Clark proposes marriage to Lois and she accepts, but shortly after their engagement party Oliver is attacked by Metropolis citizens which sparks a manhunt for Queen and the rest of the heroes. Realizing General Slade is still alive, Clark orders all heroes underground until he can find a way to stop Slade. Subsequently, Slade brings in Emil, Tess, and Lois for questioning to find out where the Blur is. Carter Hall arrives and rescues Lois, but sacrifices his own life in the process. To stop Slade for good, Clark banishes him to the Phantom Zone. The heroes come together to bury Carter in his home country of Egypt, but are knocked unconscious by an unknown object that sprouts in Carter's burial chamber.

After being knocked unconscious at Carter's funeral, Clark and his friends wake up without their powers and flashbacks of Chloe experimenting on them in a secret lab. Chloe informs Oliver that the government has put everyone in a coma and imprisoned their minds in a virtual reality. Clark and the team learn that the government is attempting to find a way to turn on and off the heroes' powers in the real world to ensure their cooperation with the Vigilante Registration Act. Chloe hacks into the program and one-by-one helps each hero back into reality. Chloe reveals that she blackmailed Flag's Suicide Squad into joining forces with her as a means of keeping them from harming innocent lives.

Tess discovers that the alternate-universe Lionel has taken over LuthorCorp under the guise that he only faked his death years prior. Martha Kent holds an anti-VRA rally that results in her being shot by a spectator. Lionel finds the Lex clone in an abandoned building and realizes that he is the one who shot Martha, though his real intention was to kill Clark with kryptonite bullets. Later, Martha confronts Lionel and Lex at the Luthor mansion, but Lex subdues the others and sets fire to the mansion. Tess convinces Lex to give up his quest for vengeance, while Clark is able to save Lionel and Martha from the fire. Afterward, Tess attempts to kill Lex but discovers he is indestructible and the superheroes watch as the VRA is repealed by voters.

As Clark makes more saves around the world, resulting in more exposure of his face, Lois suggests that he develop a better secret identity. Meanwhile, Clark discovers the work of a serial killer in Metropolis and learns that the killer is a man named Desaad, a disciple of Darkseid. Desaad finds Chloe investigating his club so he kidnaps and tortures her. Clark saves Chloe before Desaad can turn Chloe into a Darkseid follower, but a confrontation between Oliver and Desaad leaves the former with an Omega tattoo on his skull. Later, Clark explains to Lois that his real identity is The Blur, and that the persona of Clark Kent will be his true mask to the world. To accomplish this, Clark begins wearing eye glasses and changing his mannerisms to be more mild mannered.

Zatanna sends magical champagne to Clark and Lois's bachelor/bachelorette party, which causes everyone to act out of character and afterward wipes their memory. As a result, Clark and Chloe wake up believing they are married, Emil is arrested for the theft of an armored truck, while Lois and Oliver wake up in the middle of nowhere with Lois's engagement ring missing. It is revealed that Emil was actually taken by casino owner Amos Fortune, who was trying to steal the armored truck himself, while Oliver and Lois discover that Lois lost her ring to Fortune in a rigged game of Black Jack. Lois and Oliver retrieve the ring, while Clark saves Emil from Fortune's henchmen. Afterward, Chloe announces that she is leaving, and Oliver reveals that it was because they were married.

Tess reveals that Alexander was genetically engineered from both Lex and Clark's DNA. Clark takes Alexander, now going by the name Conner (CNR), under his wing and attempts to teach him to control his powers. When Clark lies about where the other half of the DNA comes from, Conner flees and is found by Lionel who slips a red kryptonite ring on Conner's hand. Without his inhibitions, Conner's dark side comes out and he attempts to force Lois into loving him. Clark comes to the rescue and destroys the ring. Afterward, Conner returns home to the Kent farm and learns that Clark has enrolled him into Smallville High as Conner Kent. Tess proves that Lionel is an imposter and retakes control over LuthorCorp. Later, Lionel is visited by Darkseid.

Martha gives Clark and Lois the deed to the family farm as an early wedding gift, and the two decide it is best to sell the farm and move to Metropolis. Meanwhile, Clark Luthor arrives from the alternate universe and sends Clark in his place before destroying the gateway between the universes. Lois quickly discovers the truth and works with Emil to bring the real Clark back. Clark Luthor reveals himself to Tess and threatens to kill her if she does not help him find Lionel. Lois and Emil are successful and the real Clark saves Tess before Clark Luthor can kill her. Clark Luthor then follows the real Clark to the Fortress of Solitude, where Clark convinces his counterpart to return to his universe and use his powers for good.

While Lois helps Clark to develop a mild mannered persona, superhero Booster Gold shows up from the future to try to take the spotlight from the Blur. Clark confronts Booster and informs him that a true hero is not made by the suit they wear, but by who they are inside. A young teen, Jaime Reyes, comes in contact with alien technology that encases him in a weaponized robotic suit, thus becoming Blue Beetle. Unable to control the suit, Jaime begins destroying property and injuring people. Inspired, Booster recounts Clark's words to Jaime and helps him gain control over the suit. Afterward, Clark convinces Booster to mentor Jaime.

After learning that General Slade escaped the Phantom Zone, Clark enters the Kryptonian prison to learn who has opened the portal. Oliver follows against Clark's wishes and the two are captured by General Zod's soldiers. Zod reveals that, upon entering the Phantom Zone, he met Darkseid who helped him become the ruler of the prison. Zod also reveals that Oliver has the Omega symbol; he then forces Oliver and Clark to fight to the death. When Zod attempts to kill Clark during the fight, the pair steal back the key to the portal and return to Earth. Afterward, Oliver sets out to find the bow of Orion with the hope that it will help them to defeat Darkseid.

Jor-El gives Lois all of Clark's powers, leaving him powerless, so that the two can see what it is like to live in each other's shoes for one day. Clark and the team discover that the imprisoned Toyman is leading a group of supervillains that include Dark Archer, Black Manta, Metallo, Captain Cold, Solomon Grundy, and Roulette. Lois receives an implant that allows Toyman to control her, and he sends her to kill the Blur. Clark is able to regain his powers in time to stop Lois. Meanwhile, Oliver and Kara team up and locate Orion's bow. Afterwards, Jor-El sends Kara to the future to forge her own destiny, as Clark is ready to accept his on Earth. Granny Goodness steals the bow from Oliver and destroys it, then sends him after gold kryptonite. Lois calls off the wedding so Clark can focus on saving people.

Tess learns that the planet Apokolips is coming to Earth to destroy humanity. While verifying the threat, Tess discovers that Oliver is under the possession of Darkseid. Desaad, Godfrey, and Granny supply Oliver with a wedding ring made of gold kryptonite to give to Clark, as it will remove his powers, but Chloe discovers the ring in time and keeps Clark from wearing it. Afterward, Clark helps Oliver to remove the Omega symbol and remove Darkseid's control over him. Lionel kidnaps Tess in an effort to transplant her heart into another Lex clone, but Tess escapes. Darkseid arrives and Lionel trades his soul for Lex's life. Possessing Lionel, Darkseid confronts Clark, who finally realizes that Jor-El was preparing him for this his entire life. Clark accesses his power of flight and vanquishes Darkseid from Lionel's deceased body. A newly revived Lex kills Tess, but not before Tess uses a neurotoxin to erase all of Lex's memories. Clark goes to the Fortress of Solitude and receives the suit Martha made for him before flying away to stop Apokolips from destroying Earth. By moving Apokolips away from Earth, Clark brings hope to humanity and breaks their connection to Darkseid. Moving ahead seven years, Lex is now President-elect of the United States, Clark and Lois are still trying to get married, and Clark has fully embraced his destiny as Superman.

A young girl named Kara Zor-El is sent to Earth by her mother Alura to protect her cousin, Kal-El, as their planet, Krypton, destructs. The planet's explosion forces her ship off course and into the Phantom Zone, where she stays for 24 years before landing on Earth. Kal-El, now an adult and going by the name Superman, puts Kara in the care of the Danvers. Twelve years later, Kara is forced to reveal herself to the world when her adoptive sister's plane is sabotaged and she must save everyone. Her sister, Alex, is revealed to be working at the Department of Extra-Normal Operations, under the leadership of Hank Henshaw, investigating alien activity. She learns that there are hundreds of aliens on the planet in hiding, most whom came from a prison that crashed on Earth when she did, and that her mother was the one responsible for imprisoning the intergalactic criminals. Her actions attract the attention of Vartox and, with guidance from Alex, she is able to defeat him. New art director James Olsen reveals he was sent to look after her and presents Kara with a gift from Superman, a new cape for her costume. Vartox's superior is revealed to be Astra, Alura's identical twin sister, who wants to conquer Earth.

In a effort to put a positive image on Supergirl in the wake of a serious mishap, Kara asks Winn and James to help her perfect her skills, while Hank and Alex put Kara through extensive physical training. Meanwhile, Kara learns that an insect-like alien of the Hellgrammite species who escaped from Fort Rozz is on Earth searching for chlorine-based food. The DEO prepares an ambush for the Hellgrammite, but it escapes, kidnapping Alex and taking her to Astra. Astra uses Alex as a trap for Kara. As Kara and Astra fight, Hank injures Astra with a Kryptonite knife and Alex kills the Hellgrammite. Learning that Kara has become more powerful than she had imagined and that humanity has a means of weakening Kryptonians, Astra muses that her "plans" may need to be temporarily postponed. Although Cat pressures James to get her an interview with Supergirl, James has reservations about being used as a go-between to his superpowered friends, while Kara is worried about being recognised. In the end, Kara agrees to the interview and prevents James from getting fired. It is also revealed that Hank might have a secret of his own when his eyes begin to glow red.

During the interview with Cat, Supergirl accidentally reveals that she is Superman's cousin. Supergirl is later attacked by Reactron, who seeks to kill her in order to get his revenge on Superman, but she manages to send him fleeing. He later goes to LORD Technology labs and kidnaps Maxwell Lord to get him to fix his suit. Kara later learns that a reactor meltdown Superman stopped in the past killed Reactron's wife, thus explaining the vendetta. She goes to Reactron's hideout and manages to save Maxwell Lord, only to get badly injured by Reactron afterwards, but Superman comes to save her. She gets mad at James, who called Superman for help, as she didn't want to rely on the Man of Steel. During a party Cat organized, Reactron breaks in to find Supergirl. While James distracts Reactron, Supergirl covers her hand in lead so that she can use it to safely remove the power core in Reactron's suit and defeat him. It is later revealed that James has an ex-fiancée, Lucy Lane (the younger sister of Lois Lane), who came to National City to patch up their relationship.

After fighting an alien escapee, Kara meets Alex at the apartment to greet their mother, Eliza Danvers, for Thanksgiving, inviting Winn due to his lack of plans. CatCo's shock jock, Leslie Willis is demoted by Cat to traffic reporting after a controversial bashing of Supergirl. During a severe thunderstorm, Supergirl tries to save Leslie, but lightning strikes them both, imbuing Leslie with electromagnetic powers. Leslie takes the name "Livewire" and tries to take revenge on Cat, but eventually Supergirl stops her and she is imprisoned at DEO. After Alex tells Eliza in a fit of rage at the dinner table that she's actually DEO, Eliza reveals to her daughters that, years ago, their father, Dr. Jeremiah Danvers, offered himself up to work for Hank Henshaw in exchange for Kara's safety and then died mysteriously, leading the girls to become suspicious of Henshaw.

Cat Grant is on leave from work, and Kara, James, and Winn struggle to take care of CatCo; Cat's son, Carter; and a bomber targeting Maxwell Lord's company. The DEO, claiming to be the FBI, goes to Lord and attempts to convince him to postpone the bullet train's opening, but to no avail. Kara is stuck between James and Lucy's relationship, each arguing that the other is responsible for their breakup. On the opening night of Lord's new bullet train, Supergirl and the DEO must deal with two bomb threats simultaneously, one at the airport and one on the train. James and the DEO go to the airport, where Hank Henshaw secretly uses his hidden strength to deactivate a bomb, claiming it was a dud. Supergirl goes to the train, which Carter and the bomber are both on. As Supergirl confronts the bomber, he claims that he was doing it for his daughter. The bomber requests Supergirl to save the people on the train, which she does, at the cost of the bomber's life. At DEO headquarters, Alex finds a fail-safe in the "dud" bomb, causing Supergirl to realize that Lord was the one behind the bomber's actions. Lord says that the threats could be used to test Supergirl's skills, but does not admit that he was responsible.

Anger issues surface for multiple characters, including Kara. Cat's mother, Katherine Grant, arrives. Lucy's father, Sam Lane arrives. The military's rogue combat android, Red Tornado, challenges Kara; she and Alex eventually defeat both the robot and its creator but the fight leaves the former weakened. It is discovered that Hank Henshaw was the last to see Jeremiah Danvers alive. At the end of the episode Kara drops some glass and when she picks it up, she starts bleeding.

The fight with Red Tornado leaves Kara helpless without her powers. During an earthquake she attempts to help James and Winn, while the events allow the alien Jemm to break out of his cell and face off against Alex and Hank, who is later revealed to be a benevolent alien refugee, J'onn J'onzz. Hank explains to Alex what happened to her father, that he saved him from the real Henshaw (who tried to kill him) and made a promise to watch over his daughter. Kara is later attacked by Astra and her assistants.

Kara's quest to stop Astra is suddenly conflicted when Astra explains why Alura sentenced her, but Kara refuses to believe her story until she discovers the truth that her mother was trying to keep from finding out. It is also revealed that Astra used her battle against Supergirl as part of a plan to take over Lord Technologies, lead by her husband Non and his army of Kryptonians, prompting Alex and Hank to stop them. The Kryptonians are also employing kryptonite-shielding devices to protect them from the substance, although Hank takes out one after he discovered that Hank was an alien. Meanwhile Kara, James, Winn, and Lucy help Cat track down a hacker responsible for releasing Cat's e-mails, leading them to a CatCo executive who wants to oust Cat from the company. Cat reveals to Kara that she has a son that she has not seen in 24 years, and later tells Kara that she knows that she was Supergirl. Kara then races over to Lord Technologies to face off against Non.

Non defeats Supergirl and leaves with Hank/J'onn. Lord sends the DEO away from his facility, vowing to defend it himself, and returns to a secret experiment he is conducting. Non offers to trade Hank for Astra, but General Lane (placed in charge of the DEO during the emergency though Hank left Alex as acting director) refuses, tortures Astra for Non's location, and walks into a trap placed by Non. Kara is distraught over both this defeat and the fact that Cat will fire her unless she is convinced that Kara is not Supergirl. Kara goes to the DEO and talks with Astra who tells her that Alura believed her (correct) claim that Krypton was doomed, but sentenced her for her illegal methods while promising to work for her cause. Alex and Supergirl make the trade over Lane's objections and Astra orders Non to withdraw despite his numerical advantage. Later, J'onn uses his shape-shifting power to present Cat with Kara and Supergirl simultaneously, casting doubt on her initial deduction of their identities.

When Winn learns that his father has escaped, Kara wants to help him find his father but conflictions are getting in his way. Alex convinces a reluctant Hank to use his powers to infiltrate Lord Technologies to find out what Maxwell is hiding. Cat hires Lucy as her general council over the concerns of James. Maxwell uses a hidden camera to spy on Kara and Alex, discovering that the two are sisters and learning Kara's secret identity. also Kara learns Winn is in love with her after he kisses her but ran off and Kara felt guilty as she told Alex who could tell between them.

Kara saves a anti-alien senator after a mysterious creature attacks, only to discover that Hank has known of the creature, who he hold responsible for killing his family and his race back on Mars, and is vowing vengeance. The deception takes on a new twist when the alien poses as the senator in order to bait Hank in a plot to kill him and Kara has to intervene before Hank goes through with his vengeance. Meanwhile, Kara helps Cat meet with her son Adam, who later asks Kara out for a date. An identical Supergirl suddenly shows up in National City, and is already the lead story on television after she tosses a dangling car off a bridge.

Kara comes face to face with a Bizarro-doppelganger of her, who was brought to life by Maxwell through a combination of genetics from her DNA and a comatose victim; the double is programmed to destroy Supergirl. Kara on the other hand, believes that Maxwell is the one the DEO should go after when she realizes he knows her secret by sending Bizarro out to kill her. Alex and Hank come up with a plan to keep Maxwell from exposing Kara while countering Bizarro with blue kryptonite. Meanwhile, Kara starts to get to know Adam but is not sure where to take the next step. A mysterious plant attacks Kara.

A mysterious plant known as Black Mercy places Kara in a dreamlike state that has her imagining that she is back on Krypton, thanks to a plot by Non, who is using Earth's technology to launch Myriad, which he and Astra are planning to use to wipe out humanity. Alex, Hank, Winn, Maxwell, and James race against time to save Kara with Alex entering Kara's world to pull her out and bring Kara back to reality. When Kara comes back she seeks revenge on Non and stops him but Astra, who wanted Kara unharmed and upset with Non, is killed by Alex before Astra could kill Hank (who fought her off as the Martian Manhunter), only to have Hank tell Kara that he killed Astra instead of Alex, who starts to feel guilty over this and whether she should tell Kara the truth. Non vows revenge on Kara in the wake of Astra's death.

Kara, Alex, and J'onn track down an armored alien known as the Master Jailer, whom they discover was a prison guard at Fort Rozz but has become a vigilante who kills alien fugitives, including those convicted of non-violent crimes, such as a professor sentences for drug smuggling. Kara confronts the Jailer but he takes her prisoner, and plans to execute her. Alex pinpoints his location near the prison crash site, and Kara is able to save the professor and defeat the Jailer. Meanwhile, Kara is steadfast against releasing Maxwell from the DEO's custody, but Cat assigns James and Lucy to investigate his disappearance. Tensions between James and Lucy develop after he finds out that Lucy photographed a DEO vehicle and revealed his knowledge of the organization, prompting James to convince Kara to release Maxwell. Kara finds competition with new CatCo assistant Siobhan Smythe, who vows to make life miserable for Kara. And as Kara and Non pay their final respects to Astra, Non warns her that she will be next. Kara attempts to seek out the truth about Myriad, only to find out that she is being kept from finding out from J'onn, and realizes that she cannot forgive him for killing her aunt.

A hacker steals information from a cheating website and asks Cat to release it. When Cat refuses, the hacker disrupts the city's infrastructure by interfering with its computer system. The hacker is revealed to be Indigo, who was on Fort Roz, and who enabled Kara to escape the Phantom Zone. Her true plan is to destroy National City with a nuclear missile but her attempt is foiled by Supergirl. Meanwhile, Kara is still mad at Hank and refuses to return to the DEO, although she does eventually, only to be told by Alex that it was she who killed her aunt.

Supergirl inadvertently comes in contact with Red Kryptonite, which destroys her inhibitions. It turns out that Maxwell created it in hopes of stopping Non's next attack. However, it gradually turns Supergirl evil. The DEO is able to subdue her - but at the price of Hank revealing himself as the Martian Manhunter.

While Kara is trying to win back National City's trust, Marine Colonel James Harper (Eddie McClintock) begins an investigation into the J'onn affair, with Lucy, having re-enlisted into the Army at her previous rank of Major, as his legal assistant. After learning that Hank and Alex are on their way to Project Cadmus, Kara tells Lucy that she is Supergirl and convinces her to help rescue Hank and Alex. Hank learns that Jeremiah is still alive, so he and Alex go on the run to find him, but not before manipulating Harper into resigning from the Marines and appointing Lucy as the acting director of the DEO. Meanwhile, Siobhan tries to get revenge on Kara for getting her fired, but gets caught and discovers that she has the power to sonic scream.

Siobhan discovers that the women in her family are cursed with the spirit of a banshee--which can only be quieted by killing whoever wronged them. Deciding to kill Kara, Siobhan frees Livewire from captivity at the DEO and suggests they team up. Siobhan—now calling herself Silver Banshee—and Livewire kidnap Cat and wreak havoc in National City Park. With the help of The Flash, a superhero from an alternate universe (see Arrowverse), Kara is able to subdue them and win back National City's trust. Later on, Kara discovers everyone in National City are now under the mercy of a mysterious mind control, revealed by Non to be the Myriad effect.

The Myriad effect has taken over National City, and even Superman is under control, leaving Kara, Cat, and Maxwell as the only ones immune. Now Kara must find a way to stop Non but Maxwell is looking at destroying Kryptonians with a bomb at the risk of killing humans over Cat's objections, prompting Kara to find an alternative. The effect brings fugitives Alex and J'onn back but not before Alex telling Eliza the truth about what really happened to Jeremiah but leave out the part about Jeremiah being alive. When Indigo senses the two returning, she defeats J'onn but takes Alex, and places her under mind control as Non's payback for Astra's death.

Kara fights with Alex, who is controlled by Non. When Alex is about to kill Kara with the same sword used to kill Astra, their mother pleads with her to stop, breaking Non's control over Alex. The team learns that hope is the key to stop Myriad. Supergirl inspires the citizens of National City, waking them from the Myriad trance. However, Non is convinced by Indigo to kill all the humans on Earth by increasing Myriad's amplitude. Back at the DEO, Max warns Kara that she might not survive a fight with Non and Indigo; J'onn later insists on helping her. Kara and J'onn confront Non and Indigo at Fort Rozz, which is powering Myriad. Kara defeats Non in a heat vision battle, and J'onn rips Indigo's body apart. As Indigo dies, she gloats that Myriad cannot be shut down. Kara flies Fort Rozz into space, rendering Myriad harmless; Alex rescues her using Kara's pod. Afterward, J'onn is reinstated as the Director of DEO, and Cat gives Kara a promotion. While Kara celebrates at her house, another pod similar to the one in which Kara came to Earth crashes near National City. Kara opens the pod and is shocked by what is inside it.

Kara finds an unknown young man lying unconscious in the pod and takes him to DEO. She prepares for a date with James just as the commercial spacecraft, the Venture, is launched into space. It suffers engine failure and descends to Earth, but Kara saves the craft with help from Superman. They discover the main target was Lena Luthor, the new CEO of Luthor Corp after her brother, Lex, was convicted of numerous crimes. In a ceremony where she renames the company L Corp, she is attacked again by John Corben, an assassin. Alex engages him while Kara and Clark stop a building from collapsing. Corben reveals he was working for Lex before he is shot by Lena. Kara chooses to be a reporter for CatCo, a decision supported by Cat. Kara and James decide to keep their relationship friendly. Winn is formally hired to work at the DEO. Meanwhile, J'onn reveals to Alex that he was the one who found the first cluster of Kryptonite and decided to keep it against the wishes of Clark, who wanted to destroy it. At Project Cadmus, an unnamed woman revives Corben and begins turning him into a being called Metallo.

Kara and Clark continue operating together in National City before he decides to return to Metropolis. However, they encounter Corben, who has turned into Project Cadmus' prototypical cyborg and challenges them by the kryptonite he empowered from. The DEO deduces that there is a mole who smuggled the kryptonite out. In another encounter with Corben, another Metallo-prototype goes on rampage in Metropolis without opposition. Alex finds the mole, who is killed by the Cadmus leader, who intends to destroy aliens. Winn manages to build an anti-kryptonite suit for Kara and Clark, who manage to defeat the Metallos by the help of Alex and Hank, respectively. Kara promises the Cadmus leader to find her. Hank entrusts the remaining kryptonite to Clark, who returns to Metropolis. Meanwhile, Cat introduces Kara to the latter's new boss, Snapper Carr, who does not like her and refuses to give her an assignment. Cat advises her to solve the problem herself, deciding to leave CatCo for other adventures, giving her place to James. Kara manages to prove her value to Snapper, who agrees to teach her. In the DEO, the alien man regains consciousness and attacks Kara.

The alien man escapes the DEO. As President Olivia Marsdin arrives in National City to sign an act recognizing the aliens, she is attacked by an unknown alien with the power to shoot fiery energy, believed to be the escapee. Alex encounters police detective Maggie Sawyer at the crime scene, who takes her to a secret bar hosting aliens. They track their target and Winn discovers that the man is from Daxam, Krypton's nearby sister planet. Kara defeats the Daxamite and locks him in the DEO. She refuses to do anything for the Daxamite, being hostile toward him because of her racial views of Daxamites and the feud between Kryptonians and Daxamites. Olivia is attacked again; the assailant is revealed to be a woman, Scorch, who is defeated by Kara, Alex and Maggie. Kara releases the Daxamite, who introduces himself as Mon-El. She tells him that Daxam's population was annihilated and Daxam is a wasteland due to Krypton's destruction. Olivia is secretly revealed to also be an alien. Meanwhile, Snapper undermines James' authority, tasking Kara to interview Lena, who reveals that L Corp has invented an alien detection device. Snapper rejects Kara's first version of article for bias tone. She decides to put aside her personal emotions in order to be a successful reporter. James forces Snapper to stay out of his area. In the bar, Hank encounters M'gann M'orzz, a female Green Martian.

J'onn asks that Mon-El stay at the DEO until he is fully examined. An alien body is found, and the DEO track down the murderer, who is kidnapped by unknown armed men. Maggie and Alex track him down to a secret facility hosting people of high political and economical status run by a woman, later identified as Veronica Sinclair, also known as Roulette. The aliens are forced to duel, sometimes to the death. They spot M'gann as a contestant before Kara intervenes and is attacked by an alien called Draaga, who overpowers her and escapes. J'onn confronts M'gann, who says that she believes herself guilty of surviving the extinction of her species. Veronica abducts J'onn and M'gann. Using Lena, Kara finds the address, where J'onn and M'gann are forced to duel until J'onn convinces her to stop blaming herself and they refuse to continue. When they are attacked by Draaga, Kara arrives and defeats him thanks to Mon-El's advice, dissuading the other aliens from protecting Veronica, who is arrested but later released by orders from higher up. Alex asks Maggie to get a drink before Maggie's date arrives, while Kara decides to train Mon-El. M'gann secretly shapeshifts to reveal that she is a White Martian.

A group of robbers, led by Chet Miner, starts challenging Supergirl using alien guns. Cadmus demands the repealing of the Amnesty as a solution. Kara deduces that Cadmus is arming Miner's team. Lena holds a fundraiser, which is attacked by Miner and his men. She reveals to Winn that the fundraiser was a ruse for the robbers, and they activate a device that destroys the alien weapons, leading to the robbers' arrest. Miner and his team are killed by Cadmus before he can expose them. The Cadmus leader is revealed to be Lilian, Lena's mother. Meanwhile, Kara takes Mon-El to CatCo for work, but he continuously ignores her commands, leading to being fired. Alex convinces her to let him choose his own path. James starts operating as a vigilante. Winn finds out and initially blames him, but finally decides to help, intending to make a suit for him. Alex learns that Maggie has broken up with her girlfriend and offers her another date, with Maggie realising Alex is a lesbian, and Alex herself accepting the fact.

In Norway, a group of scientists led by Dr. Jones discover an abnormal dead wolf, which causes the mysterious murder of all the scientists except Jones, who is revealed to be infected by a parasite. The DEO finds out that Jones killed the other scientists. Kara gets angry with Mon-El when she finds out that he uses his powers to make money. The DEO predicts Jones' next target and Kara and J'onn attempt to stop him; but the latter drains their powers, becomes larger and stronger and escapes, leaving the pair weakened and unconscious. Alex convinces M'gann to donate blood in order to save J'onn. Jones attacks his target again; but Mon-El intervenes. With his suit ready, James arrives to fight Jones too, taking the alias "Guardian". Kara regains consciousness and attacks Jones, taking Plutonium 239, which he touches, causing him to be overloaded with energy and implode. James convinces Winn not to tell Kara about his alter ego. Mon-El is abducted by Cadmus. Meanwhile, Alex tells Kara about her feelings for Maggie. Kara encourages her to date Maggie, who reveals that she prefers just a friendship, upsetting Alex.

A new vigilante appears in National City and starts killing some of the criminals James secures. Mon-El makes an unsuccessful escape attempt. Lillian demands Kara to arrive at Cadmus by threatening him. Kara arrives and is overpowered by the real Hank, who is enhanced and called the "Cyborg Superman". Winn deduces that the vigilante targets the murderers who were exonerated. The former finds the next target, with James managing to defeat the serial killer, who is arrested. Lillian, whom Kara identifies, forces her to deplete her powers, giving the former the chance to take blood samples of her. Jeremiah saves Kara and Mon-El and helps them escape by staying behind. Kara finally approves the Guardian while Alex finds out about his true identity. Mon-El develops feelings for Kara. Hank arrives at the Kryptonian base in the North Pole and uses Kara's blood to trick the system into recognizing him as her, demanding to know about the "Medusa" project. Meanwhile, J'onn begins having hallucinations and finds out about M'gann, whom he locks in the DEO. She warns him that the transfusion will turn him into a White Martian. Alex finally accepts Maggie as just a friend.

Cyborg Superman unleashes a virus in a bar, killing all aliens there except Mon-El, who is quarantined by DEO. Eliza, visiting for Thanksgiving, determines that the virus is Kryptonian. At the Fortress of Solitude, Kara learns that Henshaw was after "Medusa", a virus created by her father, Zor-El, to kill non-Kryptonian in case of alien invasion. At L-Corp, she stops Henshaw from getting the isotope required to disperse Medusa. Lena refuses to help when Kara reveals that Lillian is Cadmus' leader. Later, Lena willingly gives Lillian the isotope. Kara and J'onn confront the Luthors and Henshaw before Medusa is launched via rocket. J'onn fights Henshaw, becoming a White Martian, while Kara chases the rocket, which explodes and disperses Medusa. However, Lena has double-crossed Lillian and rendered the virus inert. Lillian is arrested but Henshaw escapes. Eliza cures Mon-El and uses Medusa to restore J'onn's Green Martian form. Alex comes out to Eliza, who supports her. Later, Maggie and Alex kiss after Maggie admits she does have feelings for Alex. An unknown alien race is searching for Mon-El. Barry Allen and Cisco Ramon arrive from another Earth to enlist Kara's help.

The episode ends with a scene setting up the crossover event "Invasion!" that begins on The Flash season 3 episode 8, continues on Arrow season 5 episode 8 and concludes on Legends of Tomorrow season 2 episode 7.

The title of the episode is a nod to the script Smith wrote for the unproduced film Superman Lives.

Winn gets beaten aiding James, leading the former to believe he is not fit for field. Kara starts investigating a strange series of missing persons. The DEO tracks the kidnappings to a fake clinical trial, which is revealed to be run by aliens. Tracking them, Kara and Mon-El pass a portal and enter the planet Maaldoria, which is the center of slave trade. Realizing that they will not have their powers due to Maaldoria's red sun, the pair tracks the kidnappees to a fortress, where they intentionally get captured and are put in the same cell as the others. They learn that Roulette is involved in the trafficking. Meanwhile, J'onn reveals that the Maaldorian atmosphere is lethal to the Martians, making Alex lead the rescue team, convincing Winn to join her. Kara incites a riot; and the prisoners lock Roulette and her Maaldorian accomplice in the cell and escape. Reuniting with the DEO, they get to the portal and return to Earth. Winn accepts his potential while Mon-El, whom the Maaldorians intentionally allowed to leave, decides to become a superhero. An alien group is revealed to be searching for Mon-El. Maggie tells Alex about her knowledge of Kara's alter ego.

Kara starts training Mon. Leslie is announced having broken out of imprisonment. Kara and Mon engage Livewire, who is revealed to be another woman, who attacks the pair with a male Livewire. Mon ignores Kara's instruction to protect the civilians in order to save her. The Guardian arrives and aids them. The Livewires escape; and Kara finds out about James' alter ego, scolding him and Winn. She also gets angry with Mon for prioritizing her over the others. The DEO learns that Leslie was actually abducted from incarceration. Winn locates her. James and Mon rush there to prove themselves. The duo is captured by the scientist, who has been draining Leslie's powers and giving them to his subjects. Kara arrives and saves them, freeing Leslie and dissuading her from killing the scientist, allowing her to escape in exchange. Kara rejects James' offer for cooperation in vigilantism. Mon confirms his feelings for her. Meanwhile, M'gann loses consciousness. J'onn agrees to bond with her. In a shared memory, he tells her that she is forgiven. She regains consciousness; and J'onn frees her. She reveals that the White Martians are searching for her.

Kara is shocked to learn that, instead of celebrating the thirteenth anniversary of her arrival on Earth, Alex has decided to go to a concert with Maggie. J'onn insists on following M'gann so as to protect her, causing her to think about whether or not she should leave the city to keep him safe. Armek, M'gann's former mate, comes to Earth with orders to bring her back to Mars for execution, and gives her two hours to turn herself in before he goes after her friends. Fearful, J'onn decides to bring her to the DEO for protection. However, when the real M'gann shows up, the other turns out to be Armek in disguise, forcing J'onn to put the DEO into lockdown. Assuming Winn's identity, Armek initiates a meltdown in the building's core reactor, while another White Martian posing as Alex ambushes Kara. J'onn and M'gann free the real Winn and Alex and confront Armek, killing him with a metal pole. Winn fixes the reactor in time, and Alex is able to subdue the other Martian. Afterwards, M'gann informs J'onn that she intends to return to her home planet in order to reform her people; they share a tender moment before she departs. Encouraged by Alex, Kara tries to ask Mon-El out on a date, only to find that he already has a relationship with Eve.

After Lena is called to testify against her mother, Kara encourages her to go visit Lillian and tell her adoptive mother how she feels about her. A package of synthetic kryptonite is sent to Corben. While testifying, he attacks the court and frees Lillian, who escapes despite Kara's intervention. The police acquire faked video footage of Lena stealing the kryptonite from L-Corp, and they arrest her on suspicion of helping Lillian. Corben is sent to break her out of prison, wounding Guardian in the process. Kara's attempts to defend Lena are increasingly met with disapproval as everyone, including J'onn and Winn, believe her to be guilty. Meanwhile, Lillian takes Lena to a remote facility set up by Lex before he was imprisoned and forces her to access a stockpile of alien weapons, several of which she takes. Kara arrives to save Lena and capture Lillian. After Lillian employs one of Lex's weapons on Kara, Lena does all she can to protect Supergirl until she is knocked out by Henshaw. Winn determines that the synthetic kryptonite is becoming increasingly unstable and will soon explode, and Kara barely manages to save Lena before Corben self-destructs, while Lillian and Henshaw escape by helicopter. Lena, having learned that she is, in fact, a Luthor by blood, contemplates her relationship with her family, especially Lex. Kara and Mon-El confess their feelings for each other at Kara's apartment when a man calling himself Mister Mxyzptlk arrives and declares his love for Kara.

Mxyzptlk begs Kara to marry him. When she refuses, he takes it as a challenge. Mon-El suggests killing Mxyzptlk, as it was the only way to get rid of imps on Daxam, but Kara insists that they find a non-lethal way of getting rid of him. Mxyzptlk summons Parasite to attack National City, knowing this will draw Kara out. Mon-El inadvertently reveals that another way to remove imps is by getting them to say or spell their names backwards. Later, Winn discovers a device in the DEO's collection that is connected to the fifth dimensional energy that Mxyzptlk draws power from. Mon-El attempts to use it to duel with Mxyzptlk to the death. Mxyzptlk eventually gains the upper hand and tries to kill Mon-El, only for Kara to arrive and agree to marry Mxyzptlk. Mxyzptlk arrives at the Fortress of Solitude for his wedding, but Kara arrives and tells that she will not marry him. Angered, he attacks her, but she stops the battle by locking the fortress down and threatening to blow it up. Mxyzptlk begs for the code to stop the countdown but, after inputting the code, realizes that it spells his name backwards and is defeated. Mon-El and Kara decide to pursue a relationship.

The DEO receives an alarm regarding a convoy departing from Cadmus. Kara and J'onn investigate and rescue a chained Jeremiah, who claims Cadmus has created a fusion bomb using energy from her heat vision. He persuades J'onn to reinstate him back at the DEO, which makes Mon-El suspicious, causing friction between him and Kara. He persuades Winn to watch Jeremiah, who attempts to access the DEO's database, alerting Winn. After confronting Jeremiah, Kara is hesitant to accept his excuse while Alex believes him. Winn locates the purported bomb; but the DEO find nothing at the location while J'onn realizes he cannot read Jeremiah's mind and that he is working for Cadmus, having become cybernetically enhanced. Jeremiah overpowers J'onn and downloads information from the mainframe before escaping. Kara and Alex confront Jeremiah, Lillian and Henshaw; Kara rushes to save train passengers Cadmus has endangered while Alex goes after the trio. Jeremiah escapes due to Alex's hesitation to shoot him. Winn later determines that Jeremiah downloaded the list of all aliens in the country.

Cadmus begins abducting aliens. Kara asks Snapper to publish an article to warn all the aliens, but he insists on knowing the source. As Supergirl, she confirms it, but refuses to reveal her own source, resulting in Snapper deciding not to publish it. Alex's obsession with Jeremiah leads to J'onn suspending her. Maggie decides to help her find Jeremiah. They capture a Cadmus team and track the site. Kara publishes the warning on a blog. Lena also finds out about the site before Lillian's operatives attempt to kill her, but Kara stops them. Alex is captured at the site, where Jeremiah reveals that Cadmus is planning to deport the aliens to another planet by a large spaceship. With Kara's warning, Lillian decides to deport the aliens she already has. Alex convinces Jeremiah to help her stop the launch. While he engages Cadmus operatives, she enters the ship and frees the aliens, who are locked inside by another gate before the ship starts ascending, programmed to accelerate to light speed once exiting the atmosphere. Kara arrives and manages to stop the ship. Snapper fires Kara from CatCo while Alex is reinstated by J'onn. The Daxamites arrive near the Moon.

The Daxamites demand the humans to relinquish Mon-El, who surrenders. Kara accompanies him and learns that Mon-El is actually the Prince of Daxam. The ship is commanded by his parents, who want him to lead his people and rebuild Daxam. Kara becomes angry with Mon-El for lying to her. She and Mon-El return to Earth. He apologizes several times, but to no avail. She eventually ends the relationship. Mon-El demands his parents to leave him and the Earth. Meanwhile, Winn and Lyra break into an art museum for a tryst. He is later arrested by Maggie, who reveals that a painting is missing. Alex convinces Maggie to give them 24 hours to prove Winn's innocence. They find and capture Lyra, who reveals that her brother, Bastian, owes a large sum to a smuggler named Mandrax. She steals paintings to pay down Bastian's debt. Winn frees Lyra as part of a sting operation. The Guardian and DEO then confront and arrest Mandrax and free Bastian. Winn later forgives Lyra's dishonesty. The DEO has captured a new alien, who quickly hypnotizes Kara and escapes to Earth-1 to fight Barry. Kara wakes up in a hallucination where she is a lounge singer.

Kara is attacked by a series of alien bounty hunters. Mon-El suspects his parents put the bounty in hopes that he will abandon the Earth if she is dead; his suspicion is confirmed after J'onn telepathically interrogates one of the hunters. Kara suggests she and Mon-El meet with Rhea, his mother, to dissuade her. However, Rhea refuses to listen and attempts to kill Kara using Kryptonite. Mon-El agrees to leave Earth if she spares Kara's life. Against Marsdin's orders, J'onn helps Kara rescue Mon-El from his parents' ship, and after a fierce battle, King Lar Gand agrees to let Mon-El stay on Earth. Marsdin is revealed to be an alien. Rhea kills Lar Gand for what she views as his betrayal, and vows to return to Earth to reclaim Mon-El. Meanwhile after an encounter with a former girlfriend of Maggie's, Alex learns Maggie omitted to tell her that she cheated on the woman, which prompts a frank discussion, with Alex asking Maggie to trust her with her secrets.

Lena invites Kara to a press conference being held by her former boyfriend, Jack Spheer, who unveils Biomax, new nanobot technology that can heal human ailments. After the conference, Kara is approached and told the human trials of Biomax were faked, but her source is killed by the nanobots before she is told more. Kara and Mon-El crash Lena and Jack's dinner date and take Jack's keycard to his office, discovering a footage showing Jack injecting Biomax into himself. Kara later shows the footage to Lena, who confronts Jack and discovers he is being controlled by his CFO, Beth Breen, and discovers the side effect of the nanobots, loss of free will. Supergirl then turns up to save Lena; but when the former is trapped by the nanobots, Lena is forced to deactivate them, killing Jack in the process. Breen is incarcerated; and Snapper rehires Kara at CatCo for providing the Biomax story. Lena is visited by Rhea. Meanwhile, Winn brings Lyra onto the team with him and Guardian, causing tensions that lead to Lyra leaving the team. James returns her to the team with the condition that she follows his instructions.

Alex is abducted by a person who demands the release of Peter Thompson, who is serving a life sentence for several felonies. The kidnapper is identified as Rick Malverne, Thompson's son and also a childhood friend of the Danvers, having deduced Kara's alter ego on his own. Rick is captured and taken to the DEO. Alex sends a location to Winn, who informs Kara, who rushes to the place, which is a ruse, and triggers an alarm, causing water to start filling Alex's cell. While the DEO and Kara refuse to negotiate with Rick, Maggie breaks Thompson out of prison before they are confronted by Kara, who convinces Thompson to reveal Alex's location. Kara and Maggie manage to rescue Alex in time. J'onn decides to wipe Rick's memory. Meanwhile, Rhea gives Lena the schematics of a high-technology device for transporting matter. Lena soon deduces that Rhea is an alien and becomes angry; but Rhea manages to convince her to continue working with her.

James becomes discouraged with being Guardian when he realizes that those he helps are afraid of him. The DEO investigates a Phorian woman who uses her telekinetic powers to cause rampage. James tracks down her son, Marcus, who refuses to speak with anyone but James, who spends time bonding with him. With Rhea's encouragement, Lena completes the matter transporter, which Rhea activates, causing Marcus to nearly destroy the office with his powers. Afterwards, the DEO discovers Rhea and Lena's involvement and that Marcus's mother's "attack" was unintentional on her part. Marcus leads James and Winn to his mother, who is with a large group of Phorians. Rhea reactivates the transporter, causing the Phorians to lose control. James manages to calm Marcus, who in turn calms the others. Kara, J'onn, and Mon-El attempt to shut down the transporter, but are unsuccessful. Mon-El confronts Rhea, but hesitates to kill her. The transporter brings a massive fleet of Daxamite ships to conquer Earth and transform it into "New Daxam". Rhea then teleports herself, Mon-El, and Lena to her ship.

The Daxamites launch a full invasion of National City, killing and arresting civilians. They also attack the DEO, but Alex and Winn manage to escape. Mon-El learns that he has to marry Lena in order to unite the people of Earth with Daxam. On Air Force One, Marsdin and Cat contact Rhea and demand their withdrawal, but the Daxamite fleet fires on them. Kara saves Cat and they discover that Marsdin is an alien, a refugee from the planet Durla. She tasks the DEO with destroying the Daxamite mother ship with a special cannon. Hesitant to do so, Kara turns to Cadmus for a way into the ship. Cat and Winn stage a distraction, inciting a civilian riot against the Daxamites, while Kara, Hank, and Lillian use a Phantom Zone projector to board the ship. Alex and Maggie regain control of the cannon, while the Luthors escape and try to disable the projector. Having predicted that, Supergirl is able to send Mon-El to safety and goes to confront Rhea, who reveals that she has taken control of Superman and has him attack Kara.

Rhea used Silver Kryptonite to manipulate Kal's senses, causing Kara to appear to be General Zod. Kara eventually overpowers and takes him to the Fortress, where a recovered Kal finds a way to end the invasion. Kara challenges Rhea to Dakkam Ur, a rite in which two leaders duel and the loser concedes the war, accepted by Rhea. Lillian, Lena and Winn build a device to disperse lead into the atmosphere. As lead is lethal to Daxamites, it would make the planet uninhabitable to them. With Mon-El's approval, Kara tells the DEO to use it if she loses. During the duel, Rhea resumes the invasion. M'gann returns with other benevolent White Martians and J'onn awakens to join the battle. Rhea claims the invasion will not stop even if she loses, so Kara launches the device, killing Rhea and forcing the fleet to leave. Kara puts Mon-El in a pod and sends him away from Earth. Cat reassumes her position at CatCo and Alex asks Maggie to marry her. In deep space, Mon-El's pod is drawn into a wormhole. In flashbacks to Krypton's destruction, an unknown faction sends another infant to Earth in order to "reign."

Kara has been dreaming of Mon-El and has become obsessive with her vigilantism, ignoring downtime with others in her life. Lena and James oppose industrialist Morgan Edge regarding his plan for waterfront housing estates. James is running CatCo with Cat serving as White House Press Secretary and Snapper on sabbatical. Kara quits CatCo, believing she needs to prioritize being Supergirl and pushing away Alex, who is making plans to marry Maggie. Edge hires criminal Bloodsport to attack the unveiling of a Supergirl statue by the waterfront with a submarine, forcing Kara to go underwater to stop them. When she passes out, her dream of Mon-El rallies her and she stops the attack. In order to nullify Edge's attempts to buy CatCo and silence it, Lena buys it herself. Kara decides to return to CatCo and rejoins her friends. Meanwhile, Samantha (Sam) Arias, a woman whom Alex helped at the waterfront, wakes up after a dream with a disturbing creature.

Kara battles a powerful metahuman bank robber called Psi, who can evoke her victims' deepest fears, forcing Kara to struggle with her memories of Krypton's destruction and her guilt over Mon-El. After Winn's psychic dampener fails, Kara finally overcomes her fear and arrests Psi. Lena decides to run CatCo personally, taking James by surprise and creating friction with Kara, who initially has difficulty separating work and their friendship. Sam Arias' daughter, Ruby, deliberately puts herself in danger to test whether her mother has superpowers, but she is rescued by Kara. Sam begins to question who she is and her origins and becomes Lena's replacement at L-Corp, acting as its CFO. Alex learns that Maggie seems to not want children. J'onn receives a telepathic summons from M'gann, urging him to come to Mars immediately.

J'onn tells Kara and Alex about M'gann's message and Kara goes with him as back-up. The two journey to Mars in his spaceship, encountering M'gann and the "resistance." They discover J'onn's father, M'yrnn, has been coerced into giving the White Martians the location of the Staff of Kolar, a psychic weapon that can defeat the resistance. J'onn rescues M'yrnn, who initially believes J'onn is a White Martian in disguise. Eventually, Kara convinces M'yrnn to let J'onn prove his identity. Having acquired the location, the resistance arrives and defeats a contingent of White Martian operatives. The recovered staff is entrusted to J'onn, who returns to Earth with M'yrnn and Kara. Meanwhile, Eliza throws Alex and Maggie a bridal shower. Alex convinces Maggie to invite her father, who comes but still cannot tolerate her homosexuality. She tells him that she no longer needs him because she now has a family who accepts her. However, she confirms to Alex that she does not want children.

The night Kara first revealed her powers and became Supergirl, a grieving passenger, Thomas Coville, was inspired by her. In the present, Kara attends an ostensible self-help group with Winn and James and discovers a "cult" made up of people she previously saved. Led by Coville, they worship Supergirl and follow Kryptonian God Rao's teachings. Those who wish to join initiate disasters so that Supergirl will save them. Coville recognizes Kara in her alter-ego when she confronts him. The group plans to blow up a stadium filled with people. When Kara tries to stop them, she finds Kryptonite inside the bomb which she uses to wound herself, thereby disillusioning the cult. Alex gets rid of the Kryptonite and, with Coville's help, pushes the bomb into a deep hole created by Kara's heat vision, where it detonates. The explosion causes a being in a vessel to awaken. Coville advises Kara to follow Rao to find her path. Meanwhile, Sam has a vision of a monstrous creature in her home, telling her she soon will "reign". Alex reveals to Kara that, while Maggie does not want children, she does.

Several children are diagnosed with lead poisoning. Morgan publicly blames Lena's lead device which repelled the Daxamites, causing the public to turn on her. She attempts to give a speech to defend herself, but ends up taking fire. Kara and Sam investigate, discovering that all the affected children attended a public pool laced with a chemical which causes the same symptoms and is manufactured by one of Morgan's subsidiaries. Lena confronts Morgan alone. She is knocked unconscious and imprisoned inside a plane with barrels of the chemical, set on a collision course for the city's water supply. Lena manages to get a message to Supergirl, who rescues Lena, secures the barrels, and destroys the plane. Morgan, however, covers his tracks. Maggie and Alex realize that, even though they love each other, they must let each other go because they disagree on having children. Alex lets Maggie know how much she has helped her happily accept herself. Maggie, in turn, lets Alex know how much stronger she grew as a person. They part tearfully, with Maggie bringing everything full circle: "See you around, Danvers." Sam discovers that she was shot during the attempt on Lena's life, but was not injured.

Kara and Alex arrive at Eliza's home to help overcome their grief, but they quarrel instead. Ten years prior, while attending Midvale High School, Alex and Kara did not get along until a mutual friend, Kenny Li, was murdered. A photograph on his laptop revealed their teacher was in a relationship with Alex's best friend. Kara sent the remaining encrypted files to Chloe Sullivan for decryption. After an attempt on Alex and Kara's lives, the teacher was arrested, but Alex discovered an alibi for him. Kara decided to cease looking into Kenny's death after a conversation with Noel Neill, an FBI agent who strongly resembles Alura (in reality, a disguised J'onn). Alex went to the sheriff for help just as Kara learned that the sheriff was involved in drug dealing and was Kenny's killer. Kara saved Alex from being killed by the sheriff. The sisters bonded and Kara decided to not use her powers again, taking Agent Neill's advice to embrace her new home. In the present, after recalling their first adventure together, the sisters reconcile and return to National City.

Kara, J'onn, and Winn investigate a crashed spaceship detected beneath National City. They find Mon-El and occupied stasis tanks aboard. They take him back to the DEO; when he attempts an escape, a suspicious Kara locks him in a cell. Mon-El convinces Winn to take him back to the ship because the life-support systems are unstable. Kara follows them. Mon-El explains that his pod went through a wormhole, bringing him to the 31st century where L-Corp had long since developed a cure for the Daxamite lead allergy. While only seven months had passed for Kara, Mon-El experienced seven years in the future. One of the tanks begins to malfunction; Mon-El cannot break it open, so Kara frees its occupant: Mon-El's wife, Imra.[8] J'onn decides to rent an apartment for him and M'yrnn to live together, taking the first step towards restoring their bond. After discovering another superhuman ability, Sam visits her foster mother and learns of her Kryptonian origins. She later travels to the "Fortress of Sanctuary", where a holographic artificial intelligence reveals that, while Sam's motherhood was unexpected, her Kryptonian physiology is enhanced and she is destined to become the Worldkiller. Despite Sam's resistance, her alternate persona – Reign – is triggered from her subconscious.

On a parallel world, Earth-X (Earth-53), a Nazi regime rules the planet where an archer, Dark Arrow, is the Führer, and personally hunts the resistance forces. Dark Arrow seizes a temporal gateway from the Freedom Fighters members including James' parallel universe doppelgänger, a device that allows interdimensional travel to other universes; he schemes to invade parallel Earths with the device to spread his reign so that it may last. Kara and Alex travel to Earth-1 to attend Barry Allen's wedding with Iris West. Alex meets the Legends' leader Sara Lance / White Canary, taking the first step to recover from her break up with Maggie. The wedding ceremony is interrupted by Earth-X Nazi invaders, led by Dark Arrow, his Kryptonian-powered wife Overgirl, and his partner Prometheus. After Kara defeats and injures Overgirl during the fight the Nazis retreat, and Alex and Sara capture Prometheus to interrogate. As Overgirl recuperates, she, Dark Arrow, and a yellow-clad speedster regroup and discuss their next move, Dark Arrow and Overgirl are revealed as parallel universe doppelgängers of Oliver Queen / Green Arrow and Kara, and the yellow speedster is Barry's nemesis from the 22nd century Eobard Thawne / Reverse-Flash.

am wakes up at home with no memory of being in a Kryptonian fortress, but finds she is oddly tired. A mysterious Kryptonian symbol, unknown to Kara, appears throughout National City and Thomas Coville later explains to her that it is a mark of a great evil from Krypton deliberately erased from its society. Mon-El and Imra explain how their ship came from the future and how the former founded the superhero team, the Legion. As Kara hosts a Christmas get-together at her apartment, Sam becomes Reign who, as a masked vigilante, attacks random people around National City, including Edge. Reign's rampage damages Supergirl's reputation due to her having the same powers and similar physical attributes. Lena and James begin a relationship after an assassination attempt on Lena by Edge. When Kara decides to face Reign, they fight throughout the city; in the process, Kara discovers that Reign is stronger than her. Though the fight clears Supergirl's name and reveals another Kryptonian in National City, Reign eventually overpowers Kara and drops her off a building, requiring emergency medical care from the DEO. On Christmas Day, Ruby runs downstairs to find her mother, but Sam does not seem quite right.

Kara's injuries are healed by the Legion's technology, but she remains in a coma following her defeat by Reign. The Legion's Coluan member, Brainiac 5, enters her mind to try to wake her. Though Sam continues her life with Ruby, Reign takes control sporadically without Sam's knowledge, and Ruby remains unaware of her mother's divided personality. Reign continues her rampage throughout National City and has a series of confrontations with the DEO and the Legion. Kara emerges from her coma to join them when Reign seeks to destroy a prison. Kara injects Reign with a concentrated dose of liquefied Kryptonite, forcing her to retreat. Prior to Kara's awakening, J'onn, who disguised himself as Kara to cover for her, advises Lena on her new relationship with James. Lena sees that James is not trying to distance himself from her because of her family, but she is afraid to be with him, and they become closer afterward. Kara takes steps to move on from Mon-El after her near-death experience, and develop a friendship with Brainiac 5. As Reign recuperates in her fortress, she learns that there are other Worldkillers like her, and Coville joins her.

Sam prepares to go on a business trip, leaving Alex to babysit Ruby. The DEO learns that a priestess with knowledge of Reign's mission is imprisoned in Fort Rozz, which is currently drifting near a blue star, which emits a radiation fatal to males and strips Kara of her powers. Kara forms a team with Imra, Livewire and Psi to locate the priestess. Reign learns of their mission and intercepts them inside Fort Rozz. The team locates the priestess and she reveals the existence of two other Worldkillers (Purity and Pestilence) before Reign kills her. Livewire sacrifices herself to save Kara's life, while Psi uses her powers to drive off Reign. Imra's ship starts drifting into the star, but Winn, communicating through the Voyager 2 probe, saves the vessel. The team returns to Earth, with Kara repaying Psi's assistance by asking the DEO to give her better accommodations. Prompted by a nightmare, Sam asks Alex for help with her "missing time". A woman named Julia Freeman is struck by a car; however, she effortlessly moves it off her chest, revealing herself to be a Worldkiller.

Lena is poisoned by an unknown hitman; James pursues him, but the hitman is shot down by a sniper. Kara and Alex are able to stabilize Lena at the DEO. Lena and Kara gatecrash a party hosted by Morgan Edge, where Lena confronts him about trying to kill her and warns that her mother wants revenge. A drone controlled by Lillian attacks Morgan, prompting him to admit he tried to kill Lena. After Supergirl arrives, Lillian attacks her with a Kryptonite blade while wearing Lex's exoskeleton. Kara and Mon-El fight Lillian until Winn hacks the drone and disables the armor. Edge is stopped from escaping with the recorder containing his confession by Guardian; Lena retrieves the recorder. Sam fears she has a brain tumor due to her memory loss, but all the medical tests come back normal. Winn, J'onn, and Mon-El deduce that the Worldkillers are genetically modified to be stronger and more able to blend into the human race than conventional Kryptonians. Suspecting the Worldkillers arrived on Earth around the same time as Superman and have secret identities, Winn discovers four possible women, including Julia Freeman, whom Kara identifies.

Supergirl and the DEO converge on Julia Freeman's home; initially she seems normal, but her alter-ego, Purity, takes over and fights them before being subdued. Sam, on sick leave from L-Corp due to her amnesiac episodes, decides to spend time with Ruby by taking her ice skating. However, Reign takes control over Sam after Purity's capture, and abandons Ruby to deal with the DEO. Ruby calls Lena after finding herself alone. Through Purity, Supergirl suspects that each of the Worldkillers' personality is split, including Reign, therefore in order to stop them they need to reach their benevolent sides. When Purity escapes, despite the heroes' attempt to recapture her, Julia regains control but Reign abducts her to the Fortress of Sanctuary to complete her transformation. When repairing the Legion's ship, Mon-El confides to J'onn that he still loves Kara despite also loving Imra, and he did not marry her on his terms. Imra confesses to Mon-El that she and Brainiac 5 have a secret agenda on their mission. At L-Corp, Reign briefly takes control over Sam in front of Lena.

Kara, Alex and Winn attend his father's funeral. Winn is approached by his estranged mother, Mary, with Winn remaining distant. Kara saves Winn and Mary when the coffin detonates. Mary reveals to Winn that after trying to escape to an abuse shelter, Winn's father ran them off the road and threatened Winn's life if she ever went near him again. Flying monkey toys attack the DEO, which Kara and James fend off. Mary helps her son analyze the toys to discover their origin. Mon-El attempts to reconnect to Kara and reveals the Legion came to National City to stop the Worldkiller Pestilence, who will transform into Blight in 1,000 years. Toyman's penitentiary officer, who sent the toys, kidnaps Mary and holds her at an abandoned toy factory. Kara, Mon-El and Winn save Mary after battling a toy dinosaur and incapacitating the officer. James calls up Lena, who claims to be busy with L-Corp work; she is keeping Sam in a locked medical bay in L-Corp under sedation.

Lena brings Sam out of sedation and tells her that her blood tests are normal, but further analysis shows Sam undergoes a metamorphosis at the cellular level when she becomes Reign. Sam refuses to believe her even when shown images of Reign that correspond with the times of her blackouts. At the DEO, M'yrnn performs a ritual to help preserve his mind, but the psychic bleed affects everyone by bringing out their aggression, except for Mon-El (whose Legion ring protects him). Mon-El trains Supergirl on how to use her cape during combat. M'yrnn's ritual causes chaos around the DEO. J'onn convinces M'yrnn to wear a power-dampening bracelet to stop the psychic bleed after a White Martian and other prisoners escape their cells. Lena pushes Sam to the limit emotionally, threatening to keep Ruby away from her, which causes Sam to turn into Reign. After she regains control and Lena shows her video proof of Reign, Sam asks Lena to keep Ruby away from her until she is cured.

The DEO investigates the rash of dead animals; it spreads to humans, as people develop flu-like symptoms with a large scratch on their wrists. Imra believes this is the work of Pestilence, the third Worldkiller. Winn and Alex become part of the infected; Brainiac 5 creates a cure using a blood transfusion from Mon-El and Imra, though it fails. The DEO discovers the person behind the attacks is Grace Parker, who has fully accepted her powers and role as a Worldkiller. Supergirl, Mon-El, and Imra battle Pestilence until Purity arrives to help her escape. Imra is able, however, to gain a blood sample from Pestilence for Brainiac to manufacture a working cure. Lena still holds Sam at the L-Corp lab to run tests, where she causes Reign to appear for brief moments so she can learn more about her. While in Sam's mind, Reign tells her they are coming for them. After detecting Purity and Pestilence approaching L-Corp, Kara, Mon-El, Imra, and J'onn go to warn Lena where they discover Sam. Purity and Pestilence arrive, freeing Reign, and the three fly off together.

Lena is questioned at the DEO and reveals that she contained Reign using the last of Lex's Kryptonite. At the Fortress of Sanctuary, the Worldkillers work to bring about a total eclipse. Grace is dead, but Sam and Julia are still fighting to remember their human lives and stop the Worldkillers from taking control. Kara asks James to make sure Lena does not possess more Kryptonite; however, James decides to take Lena's word. Brainiac 5 broadcasts Supergirl, Alex, and Lena's minds into Juru, a Kryptonian valley, where they track down Sam and Julia. Sam is reminded of Ruby, which prompts her to retake control of her body on Earth. Sam activates a location beacon for the DEO just as Brainiac pulls Supergirl, Alex and Lena out of Juru. Reign takes back control as the DEO arrive in the Legion ship. A fight culminates in Purity and Pestilence killing each other and Reign absorbing their powers, causing the fortress to collapse. James tells Lena he is Guardian and that Supergirl asked him to confirm there was no more Kryptonite. Lena admits that she made the Kryptonite herself. Reign decides to go after Ruby.

Lena and James are attacked by Reign at Lena's place. Lena uses Kryptonite against Reign which forces Reign to retreat. However, Lena learns about Reign's hunt to kill Ruby. Legion's members prepare for return to their time. Lena tells Supergirl and Alex about Lex's mansion where she had arranged for Ruby's stay. Alex visits Ruby to keep her company. Supergirl and J’onn visits Sam's mother to keep her safe from Reign and to set a trap for her when she comes looking for Ruby there. However, Reign kills Sam's mother. Supergirl and J'onn come to know that Reign now has the powers of all three Worldkillers. Reign attacks Alex and Ruby in the mansion, leading the latter to discover her mother's split personality. Mon-El stays behind to help Supergirl. They were able to capture Reign with the help of Kryptonite created by Lena. Later, Alex comforts Ruby following the revelation; Ruby now fears for her mother and herself, knowing that she is Reign's child. Lena tells Kara that Supergirl crossed a line by using her personal relationship with James and will never trust her again, leading to Kara to abashed of her actions and doubting herself of her ethics.

Kara and James discuss Lena's mistrust of Supergirl and keeping secret identities. Tonya, a Coville follower, brings Coville's personal journal for James to give to Supergirl. Mon-El and Kara find remnants of a nuclear explosion at the cult's last location. The cult kidnaps Tonya from CatCo, pursued by Guardian. In the ensuing fight, Olivia (the cult's new leader) shoots off James' mask and the cult escapes after the police arrive; the cult later demands Tonya and the journal from James, threatening to reveal Guardian's secret identity. From Coville's journal, Kara realizes the cult is trying to make a new Worldkiller using Harun-El (a Black Kryptonite). Mon-El purposefully gets kidnapped by the cult as Tonya turns herself over to them. As Olivia starts the ritual to transform herself into a Worldkiller, Mon-El sends a signal for Supergirl to locate them. After a brief fight, Supergirl reasons with Olivia enough for her to give up the desire to be a Worldkiller. Winn and Lena find more of the Harun-El, which can be used to help Sam, on a meteor; Mon-El and Kara fly J'onn's spaceship to travel there.

Kara and Mon-El reach the meteor and discover there is a city on it. They are attacked by caretaker droids, but use disguises to blend in while traveling through the city towards the rock. Alex is attacked while spending time with Ruby. She initially suspects it is the killer sheriff she and Kara helped capture ten years ago, however a second attempt is made on her life. Kara realizes the meteor is a surviving part of Krypton, Argo City, and discovers her mother is alive. Alura arranges for a meeting of their High Council to discuss the issue of the Harun-El, as it is used to sustain the life and security of the city. Kara manages to convince the members of the High Council to give her a small quantity of it to defeat Reign. Alex and J'onn set a trap for Alex's killer by J'onn posing as Alex, but he targets the real Alex before she captures him. Later Selena, a High Council member, is revealed to be a Dark Priestess. Kara and Mon-El arrive back at L-Corp just as Reign's increasing immunity to Lena's Kryptonite allows her to escape containment.

Kara and Mon-El fight Reign as Lena creates an antidote from the Harun-El. Once injected, Reign separates from Sam and disintegrates. Sam reunites with Ruby at the DEO and Kara asks Lena to artificially reproduce the black rock for Argo City. Kara decides to return to Argo City to be with Alura and she invites Mon-El to join her. Winn and James discover a gun from the DEO is being used on the street as they monitor National City's security for Kara. James and J'onn learn the gun manufacturer sold a version of the DEO weapon to the general public and J'onn later mandates that the DEO switch to non-lethal weaponry. Back in Argo, Kara is followed by a woman, who identifies herself as a Dark Priestess and Selena as her High Priestess. M'yrnn and J'onn discuss performing the Reach, a Martian ritual for an elder to pass on all memories to a younger family member. Kara and Mon-El discover that Selena and the other priestesses stole their ship and Coville joins them when they arrive on Earth.

Coville, Selena and the other Kryptonians begin a ritual at the Fortress of Sanctuary to summon Reign back to Earth. However, her body will not completely form and Selena determines they require the blood of Pestilence and Purity. Sam undergoes testing at the DEO and M'yrnn and J'onn begin the Reach. Kara uses Alura's hologram crystal to contact Winn and explain Selena's plan to conquer Earth. Winn replicates a portal in the DEO as Mon-El fixes the one on Argo to travel between Argo and National City. The Kryptonians break into the DEO to locate the Worldkillers' blood. Kara, Alura and Mon-El travel back to Earth to join the fight and the Kryptonians leave once they possess the blood. They complete the ritual but Selena kills Coville. Lena determines that as Reign gets stronger, Sam gets weaker. Alura reveals there is a fountain that can strengthen Sam and weaken Reign; Sam travels to Juru to find it. Reign begins traveling to the Earth's core with the sword of Juru to terraform Earth into a new Krypton, which sets off earthquakes.

As the earthquakes worsen, Supergirl, Alura, Guardian and the DEO protect National City; Imra and Brainiac 5 return to help. M'yrnn gives J'onn one final memory before merging with the earth to stop the terraforming and the heroes defeat the priestesses. Sam finds the fountain in Juru and makes peace with her mother. She drinks from the fountain and defeats Reign using the sword. However, this leads to Sam, Mon-El, and Alura dying, so Supergirl goes back in time and changes the outcome of their fight using the Harun-El. Brainiac 5 decides to stay on present-day Earth because a distant relative (who did not die in the Blight) has started wiping out all other AI and asks Winn to take his place with the Legion. Winn accepts his offer and travels to the future with Mon-El. J'onn steps down from the DEO and promotes Alex as director. Kara decides to stay on Earth instead of returning to Argo with her mother. Sam, completely rid of her Kryptonian side, returns to her life with Ruby. Lena gives Alura all of the Harun-El and a mathematical formula to create more, but synthesizes a portion for secret experiments. A duplicate Kara appears in Siberia at the same time Reign is defeated with the Harun-El.

Kara has stayed busy in her heroic duties working with the DEO, and as a reporter at CatCo proving she can multitask. Brother and sister Otis & Mercy Graves attack an alien, Dr. Vose, and steal an EMP device from his lab. J'onn believes it to be a hate crime, with the recent rise in anti-alien hatred in the country, although Kara disagrees. The duo plan to attack President Marsdin's summit to mark the anniversary of her amnesty act. Supergirl saves the President and captures Otis, but Mercy escapes. Camera footage of the attack ends up exposing the President's true identity as an alien. Meanwhile Alex and Brainy struggle to communicate with each other at the DEO. The Graves are working with a mysterious masked individual who says he is an "agent of liberty" as he stabs Fiona Byrne, an alien telepath that J'onn had met in a support group for other aliens. The duplicate Kara is seen punching through walls in an underground cavern surrounded by Kasnian soldiers.

In the wake of President Marsdin's outing as an alien, a wave of anti-alien sentiment spreads across the country. Mercy hacks L-Corps' image inducers to disable them, in an effort to force aliens out of hiding. When Brainy is outed, he is rattled by the hatred he faces. J'onn continues to investigate his friend's disappearance and the trail leads him to Agent Liberty, who holds an anti-alien rally. At L-Corp, Mercy and Lena fight, each using an arm piece of Lex's exoskeleton. Mercy is captured by Supergirl and held at the DEO with Otis. Nia, who reveals herself to be transgender, convinces James to write an editorial against anti-alien hatred. Mercy and Otis convince an agent, Jensen, to release them. Using Lena's lead dispersion device, the three send Kryptonite into the atmosphere, which hits Supergirl mid-flight, making her pass out and fall to the ground.

'onn catches Supergirl before she crashes to the ground; he brings her to the DEO and the Kryptonite in the atmosphere continues to weaken her. In an effort to keep her safe while a cure is found, Lena outfits Kara in a prototype armor that will help filter the Kryptonite out of her system. In a series of flashbacks, Ben Lockwood, a university professor, and his family suffer a series of personal tragedies that slowly turn him against aliens and lead him into the path of Mercy Graves, who gives him the Agent Liberty armor. Back in the present, Ben prevents Mercy and Otis from killing Jensen by blackmailing the young agent into breaking them into DEO headquarters.

With the air still Kryptonite-saturated, Kara is not permitted to leave the DEO and fight as it may damage the suit and kill her. Lena and Brainy devise a method to filter the Kryptonite out of the atmosphere. A second DEO agent turns rogue and breaks two aliens out. Mercy kills him after he brings the aliens to her. J'onn meets Manchester Black, Fiona's fiance. Ben hypnotizes the aliens, using Fiona's telekinetic powers, into committing chaos, to give justification for killing aliens. As they attack a carnival, Supergirl fights until her suit is damaged. J'onn and Manchester join the fight and find Fiona, breaking the hypnosis on the aliens. Mercy and Otis corner Alex and Supergirl where Otis threatens to expose Supergirl to the Kryptonite-filled air. One of the aliens kills Mercy and Otis as the air is completely cleared of Kryptonite. J'onn is only able to ease Fiona's pain before she dies. Later, Ben transfers a parasite into Jensen, and Manchester purchases lethal weaponry. President Baker assigns Colonel Lauren Haley to be Alex's commanding officer at the DEO.

The parasite enables Jensen to absorb an alien's powers through touch, while also killing them. Jensen uses his powers in public and weakens Supergirl enough to escape. Kara and Nia interview a healer alien, Amadei, to counter the anti-alien rhetoric. Amadei is then attacked and left to die without his healing amulet. J'onn and Kara discover the amulet was stolen for the Children of Liberty, to stop Jensen's new powers from killing him. Colonel Haley obtains uranium to use against Jensen and the DEO sets up a containment dome to limit the blast radius. James and Lena meet Ben Lockwood at a media summit, where James asserts that Guardian does not stand for Ben's anti-alien sentiments. Alex convinces Jensen to remove Amadei's amulet, leading to him becoming brain-dead. James believes that if he understands the anti-alien movement, he can get those people to listen, so he contacts Ben Lockwood.

Masked citizens calling themselves the Children of Liberty patrol the streets, attacking innocent aliens. Supergirl and Manchester Black intervene and chase them off. Anti-alien manifestos entitled "Twilight's Last Gleaming" rain down on them. Manchester Black has Children of Liberty member Petrocelli held captive to torture him for information. Haley reprimands Supergirl for intervening in the attack and refuses to use DEO resources to investigate the manifesto. Lena and Eve are frustrated that their experimental trials with the Harun-El rock are not successful. Kara replaces James on a television show where she ends up debating Ben Lockwood, who gets the best of her. James meets Tom, a Children of Liberty member, and they patrol neighborhoods with a dog that can detect aliens hiding. Then the group starts putting together the clues: the alien-sensing dog allowed the Children of Liberty to identify alien houses, and the special lenses that Manchester discovered in Petrocelli's mask will allow the Children to see the infrared marks. At CatCo, Nia's narcolepsy alarms Kara and James. Brainy removes the infrared marks and defeats a group of Children and Kara saves an alien family from Children.

Supergirl is lured by Manchester Black to Shelley Island, an alien immigration center and monument site where their powers are dampened, where the Children of Liberty detain her and lock her inside the monument and set it to detonate. James investigates the area, and is almost convinced by the Agents to detonate the monument, but Kara, whose powers are only partially drained, manages to attract his attention with her heat vision. Manchester, realizing the Children were playing him, destroys the power dampeners, allowing her to escape and Manchester and James to fight off the Children. Meanwhile, Lena proceeds with her experiments to enhance humans in an effort to "level the playing field" between humanity and super-beings. She takes on a volunteer that identifies himself as Adam; he lost his brother during a kidney transplant operation and remained grief-stricken and mourning his loss. Shortly after Lena shares her own motivational grief--the loss of her mother when she was 4, which led to her being adopted by the Luthor family--Adam soon dies during the trial, after both bond. James, unaware of the experiments, goes to make up with Lena. Kara, Alex and Brainy are visited by J'onn who is upset about not being able to stop Manchester from killing people.

Nia wakes up suddenly from a dream involving Agent Liberty. Kara and J'onn look through Manchester Black's apartment. Kara and Brainy help Nia with her dreams which lead to the old Lockwood Factory where they confront Ben who was confronted by Manchester Black who threatened to kill his wife. Kara stops Manchester Black from killing Ben's wife and sends Ben and Manchester to prison where the latter is visited by J'onn. Later, President Baker demands Supergirl to reveal her secret identity to the world. She refuses, so Baker fires her from the DEO.

Barry Allen and Oliver Queen wake up as wanted criminals hunted by John Deegan as a black suited Superman while Kara is imprisoned at S.T.A.R. Labs, with a rewritten Alex guarding her. After narrowly escaping Deegan, Barry and Oliver locate Cisco Ramon, who works as a mob boss with James as a henchman, and retrieve Superman from Earth-38. Supergirl convinces Alex to release her, and together with Barry retrieves the Book of Destiny. Superman uses the book to return Barry and Oliver to their original forms, but Deegan steals it back. Barry and Kara travel in opposite directions to slow the Earth's rotation in order to impede Deegan, despite Clark saying it will kill them. With help from Lois, Brainy, and J'onn, Superman and Oliver successfully defeat Deegan and restore Earth-1 to normal. On Earth-38, Clark reveals Lois is pregnant, and they are going to be moving to Argo City for a while, leaving Earth in Kara's hands. Clark proposes to Lois and she accepts. On Earth-1, Oliver gets a call from Batwoman, revealing Deegan is in Arkham and has seemingly made friends with the Psycho-Pirate.

Kara finds a boat where a man named Randall McAllister is killed and dragged into the ocean by a slightly visible alien. Colonel Haley dismisses Kara from the crime scene because of her continued refusal to reveal her identity. All the D.E.O. agents who know Supergirl's identity, including Alex, agree to resist Haley's interrogations. Kara, Alex and J'onn learn that the attackers were Morai, a trio of aliens with the ability to turn invisible with only Kara being able to see them. One Morai kills itself to avoid Haley, who, alongside McAllister, tortured them to be weapons. Two more Morai infiltrate the D.E.O., and Brainy marks them with a paintball gun so the agents can see them. Haley re-enables the use of lethal weaponry, killing one of the Morai. Haley and Alex are saved by Supergirl from the last Morai. Haley realizes that Supergirl is Kara, and tries to blackmail her back into the D.E.O. before Alex incapacitates her. J'onn wipes Haley's mind of Supergirl's identity, but Haley remains determined to discover it, bringing in an alien truth-seeking creature to ferret out the secret. To keep Kara's identity safe, Alex has J'onn wipe everyone's memory of Supergirl's identity including her own.

The Supergirl clone falls into a coma. The Russians try to revive her, but sends purple lightning around the globe; causing illegal tablets to glow purple. People taking the purple drugs temporarily transform into unstoppable monsters, catching the D.E.O.'s attention. While chasing these monsters, Kara has a disconnect with Alex due to her no longer remembering her secret identity. Alex feels that something inside her is missing, so she asks J'onn to take a look. J'onn and Brainy agree to place a placebo in Alex's mind to cover the truth. Meanwhile, Nia has ill confidence about her family when she develops the unwanted Dreamer powers that occur to one female in every generation in her family. Nia's sister (who was taught dream interpretation while expecting to gain the powers) discovers Nia has the powers and regretfully renounces her. Kara reveals her identity to Nia to reassure her. While Nia's mother lays dying of a spider bite, Nia uses her powers to talk to her mother about them, who assures her she'll be able to continue the dreamer line.

After a meteor crash lands, Pamela Ferrer, a thief, and her boyfriend are caught in a car crash. A symbiotic, snake-like alien parasite known as Menagerie inhabits Pamela's body. Meanwhile, Brainy requests Nia to train with him but refuses as she is still grieving her mother, although she decides to invite Brainy to a Valentine's Day party. Alex decides to give advice for Brainy. Lena decides to share her research with the government, causing James to break up with her as that could be weaponized. Ben convinces his son to lead the Children of Liberty. After, the D.E.O. track down Pamela who attacks the Valentine's Day party. Following a confrontation with Kara, Nia and the Children of Liberty, the parasite is (apparently) killed. Pamela is arrested and put in prison where she gets a message from Manchester Black. President Baker realizes crimes are only considered terrorist attacks if they are against humans, not aliens, forcing him to release Ben from prison. It is revealed that the symbiote is still alive.

Manchester breaks out of prison with Hat and Menagerie who together form "The Elite," along with a Morai. Hat is revealed to be an alien whose Bowler hat has fifth-dimension properties. Meanwhile, Brainy trains Nia at the Fortress of Solitude. Supergirl confronts President Baker to convince him to prevent a missile launch carrying a satellite which would destroy any alien ship coming to Earth, but he refuses. Later, Supergirl, Nia, Brainy, Alex, and J'onn stop The Elite, while Supergirl learns that the Claymore satellite has been reprogrammed to destroy The White House. She redirects the satellite so that it fires at a body of water and then destroys it. However, Manchester manages to flee with the Legion ring he stole from Brainy during their confrontation. Ben is offered to be Director of Alien Affairs by the President. At the same time, Alex begins distrusting Baker after Haley confirms that the President took action against protocol; to this end, she offers Lena anything she needs for her research. After being visited by Supergirl following the incident, Baker makes Ben the Director of Alien Affairs but denies his request to deputize the Children of Liberty.

Ben starts a revolution against aliens, attempting to repeal the Alien Amnesty Act, which gets The Elite's attention and they decide to help the aliens resist against the humans. However the revolution eventually fails when aliens and humans begin to bond. Supergirl, Nia and J'onn defeat the Morai, The Hat and Menagerie. J'onn fails to stop Manchester so he decides to begin a manhunt. At Cat Co, James gets shot by an unknown figure.

Four years ago, Lena's brother Lex created a red sky over Metropolis to take down Superman, but was caught and sent to prison. In the present, Lex is released due to a disease, so Lena helps him by working on a cure. Meanwhile, J'onn and Kara continue investigating Manchester, who confronts the two by using the Martian Staff of Kolar, which triggers J'onn's traumatic memories. Lena decides to use the cure on a temporarily dead James. Though his sister Kelly tries to stop her, Alex convinces Kelly to stop. Just before Lena's able to, Manchester causes a power outage across the city, so Kara and J'onn confront him again. J'onn kills Manchester while Kara stops the city from being flooded. The following day, Lena reveals that Lex cut off the backup power, and he also admits that Otis (thought dead) shot James on Lex's orders all so that Lena would have no choice but to test the cure on him. It is also revealed that Eve was working with Lex and Otis this whole time. Otis chloroforms Lena, leaving Eve to look after her. Lex escapes with Otis, but is stopped by Supergirl.

Three years ago, Lex was put on trial for mass murder but before going to prison he is visited by Eve (revealed to be a fangirl of Lex), who is hired by Lex to go undercover to spy on James. Nine months ago, the Kaznians found a stray, amnesiac copy of Supergirl, who was created from Harun-El, and informed Lex about this four months later. Since then, the Kaznians have been training the Supergirl copy while Lex raised and manipulated her for his own uses, teaching her a biased history about her rival, the original Supergirl. It is also revealed that Lex planned for Lena to test the cure in order to save the Supergirl copy from a sudden illness that rendered her comatose due to her being created from Harun-El. Lex gives the cure to the Supergirl copy whom he names Red Daughter. In the present, Lex is revealed to possess metahuman powers, which he uses to escape from Supergirl.

Supergirl teams up with Alex and Lena to track down Eve. They find her cousin Bitsie, whom they learn was given the cure to eradicate her cancer; persuaded to help, Bitsie reveals the location of Eve's old lab. It is revealed that Eve shot James and used the Kryptonite heart used for Metallo to resurrect Otis. Supergirl finds Black Kryptonite in the vault, with Lena explaining she created it and it has been the basis of her medical research. Supergirl reveals her concerns about people like Lex gaining powers and her not being able to stop them. J'onn leaves the planet after seeing a vision of his father. During a press conference at the White House, in which the Alien Amnesty Act is officially repealed, Red Daughter attacks disguised as Supergirl to turn public opinion against the latter. President Baker declares martial law against Supergirl, who is now public enemy number one, though Alex, Lena and Haley all believe she is innocent. While attending the press conference, James is left unable to move out of fear, so he turns to his sister for therapy.

Red Daughter attacks the White House disguised as Supergirl, but James, Nia, Alex, Lena, Brainy, and Haley are not fooled. Ben demands the use of the DEO's alien weapons to arrest Supergirl. Brainy realizes Ben will come for the alien registry next, so he downloads a copy of it before deleting the original. A reluctant Haley agrees to Ben's request, and borrows Alex's signal watch. Alex lies about how to summon Supergirl. Despite seeing through it, she presses it so that Supergirl does not show up, Ben makes off with the weapons. Baker grants Ben's previous request to deputize the Children of Liberty. James has another PTSD episode but the psychiatrist's anti-PTSD advice has little effect due to his powers surfacing. Supergirl and Lena visit Stryker's island for information and discover Lex's hidden room. Otis, now an advanced Metallo, attacks Supergirl and starts a prison riot before self-destructing in the secret room. Eve secretly works on rebuilding Otis. Steve Lomeli, Lex's cell neighbor, gives her a flash drive on the room. Supergirl is framed for the riot, so Kara decides to stop being Supergirl for a while, claiming to Alex and Lena she is "going into hiding."

With Kara ceasing to operate as Supergirl, Dreamer takes her place as National City's superhero. Ben returns to his duties as Agent Liberty. Now deputized, he and the Children of Liberty begin arresting innocent aliens. His son realizes his best friend is an alien, having kept this a secret because of Ben's policies, which makes him reconsider his parents' anti-alien propaganda. Brainy and Kelly try to discover the source of James's PTSD, discovering that panic attacks make his powers develop faster; his powers are revealed to be identical to Kryptonians. Kara works to clear Supergirl's name, as she and Lena discover Lex's link to Kaznia, as well as a company called AmerTek. An alien whose husband was arrested by the Children of Liberty kills Ben's wife. J'onn completes his mission on Mars.

James tests his powers in the Fortress of Solitude. Lena and Kara go to Kaznia for information on Lex and discover Red Daughter's existence as well as her role in Lex's plot to invade America. Eve creates clones of herself to throw the duo off and sets off the facility's self destruct. Kara discovers and burns Red Daughter's room and realizes Lex knows that she is Supergirl. She and Lena defeat the Eve clones and escape; having collected evidence of the impending invasion. The D.E.O. tracks down Ben's wife's murderer. Ben orders all aliens at that location to be arrested, but his soldiers are convinced to disobey orders by Brainy. Ben takes the super serum to arrest them himself, but he is subdued by a returning J'onn. Ben is denounced by his son because of his anti-alien rhetoric. Kara meets Baker in his office to warn him about Lex's plot, but he has her black-bagged, revealing he is in on the plot.

Baker has had the CatCo servers wiped, terminating Kara's evidence. Kara escapes an execution at the hands of Red Daughter. Lena interrogates Ben about Lex's plan, but he is unaware of it. Ben's hair begins to fall out as he has taken an untested Harun-El. J'onn, Brainy, and Nia infiltrate an AmerTek factory to save the aliens there, but are captured. One of the agents strikes Brainy in the forehead, inadvertently causing him to behave like his ancestors while rebooting. He escapes and betrays J'onn and Nia, getting them deported with the other aliens. Ben finds Otis, who unknowingly reveals that Lex plans to betray Kaznia before getting killed by him. Lena places a baby truth creature around Lillian's arm and is convinced by her to add more Harun-El to James after he becomes traumatized. Red Daughter appears at Alex's home, disguised as Kara, before Supergirl arrives and fights her. Alex remembers again that Kara is Supergirl. Red Daughter nearly kills Kara, but Lex apparently kills Red Daughter on television. Baker lies that he killed Supergirl, framing her as the mastermind behind the Kaznia invasion. Haley calls Alex to inform her about the true purpose of the Claymore satellite: it has enough energy to power a Lexosuit.

Lex has framed himself as a hero for stopping his self-initiated Kaznian invasion. J'onn and Nia are sent to Shelley Island, where enslaved aliens are setting up a Claymore satellite on Lex's orders to destroy Argo, where Superman is. When Lex and Baker find out Ben killed Otis, they make it seem like he is responsible for Lex's crimes. Ben watches as Baker makes Lex the new Director of Alien Affairs. Kara recovers her evidence from Brainy and publicly exposes Lex and Baker. J'onn and Nia escape and overload the satellite, while Brainy returns to his normal-self. Kara, Alex and James arrive at Shelley Island and fight Lex and Ben. James and Ben remove the Harun-El from each other, costing James an eye, while Red Daughter, who was held captive on the island, sacrifices herself to save Kara. She fuses with Kara, who uses her newfound powers to destroy the Lexosuit. Lex teleports away, but is ambushed by Lena, who removes the Harun-El from him, before shooting him. However, before dying, Lex reveals to Lena that Kara is Supergirl in an attempt to embitter her, which succeeds. Ben and Baker are arrested, while the Vice President re-initiates the Alien Amnesty Act. Kelly and Alex reveal their feelings for each other. Eve tries to escape, but is intercepted by a representative of Leviathan, who refuses to let her go despite Lex's failure, revealing they forced her to work for Lex. Elsewhere, The Monitor releases J'onn's brother on Earth before retrieving Lex's corpse.

After discovering Kara Danvers' secret identity from her brother Lex Luthor before she killed him, Lena fights Kara in a virtual simulation and has built an A.I. named Hope to talk to as she no longer trusts anyone. Meanwhile, Andrea Rojas acquires CatCo, replacing James Olson as editor-in-chief, and employs tabloid journalism to increase subscription numbers. Alex Danvers convinces Kara to tell Lena that she is Supergirl, so she tells her at a party celebrating her Pulitzer Prize. Suddenly, the party is attacked by Midnight, a Phantom Zone prisoner that J'onn J'onzz defeated years prior. Kara reconciles with and reveals her identity to Lena before using a new suit Brainy created for her to stop a black hole Midnight opened and send her back to the Phantom Zone. While Kara shows more openness to Lena about her secret, Lena re-enters the simulation to vent; pledging to use Kara's trust to "fix mankind". James quits CatCo, refusing to support Andrea's sensationalist plans. Elsewhere, J'onn's brother, Malefic, vows to get revenge himself following Midnight's failure despite J'onn not remembering having a brother while Eve Teschmacher returns to National City on Leviathan's orders, but gets black-bagged.

With Kelly Olsen's help, J'onn learns that his memories of the Martian Civil War were altered, but that Malefic was his brother who betrayed the Green Martians to aid the White Martians. J'onn and Malefic receive immense pain whenever they attack one another due to a curse, which J'onn still suffers from, so he asks Kelly to soothe his pain using Q-waves, but Malefic secretly sees this and realizes Q-waves can help further his revenge against his brother. Meanwhile, Lena reveals to Eve her plan to use Andrea's technology to improve humanity by giving them Hope's altruism and loyalty before having Hope take over Eve's body. Elsewhere, Kara chafes at her new work assignments, and rival reporter William Dey seems to be on the trail of her secret identity.

J'onn requests Nia Nal's help in delving deeper into his past, finding that he used his telepathy to erase Malefic from his father's memory since the latter blamed himself for Malefic's isolation due to his unstable power. Malefic attacks Kelly, who he tricked into revitalizing his suppressed mind control powers, but escapes after a confrontation with J'onn. Kelly is revealed to have developed a psychic link with Malefic when she returned his powers and identify him in a shapeshifted form. Meanwhile, Kara, Alex, and James track down an alien with the ability to shoot cobwebs. They find the culprit in former special ops commander Caroline O'Connor, who is possessed by the spider-like Aurafacian symbiotes. Alex uses a device to remove the Aurafacians from Caroline's body. However, she is later mysteriously killed by an unknown person before she can be taken into D.E.O. custody. Lena asks Kara to steal Lex's childhood journal and discovers his research on mind control. Nia confronts Brainy about their relationship.

With Nia's help, Kara discovers that William is an undercover reporter who suspects that Andrea is a criminal. She prevents a new supervillain called Breathtaker from assassinating Elena Torres and has her remanded to the DEO. Meanwhile, James and Kelly return to their hometown, which they find corrupted by the presence of a new prison, where people receive unjustly long prison sentences for minor crimes. They meet a teenager named Simon, who James helps in his mother's case. Elsewhere, Malefic takes control of Alex, but she is saved by Kara and J'onn and seemingly send him to the Phantom Zone. Brainy and Nia reconcile their relationship and James leaves National City to take over his hometown newspaper. Unbeknownst to Kara and her allies, Malefic was teleported into Lena's office instead, where Lena forges an alliance with him.

Lena promises to help Malefic overcome his inhibition to kill J'onn in exchange for experimenting on him to duplicate his mental inception power. However, she reneges and uses the power to keep him in captivity. Kara and William pursue leads involving an assassin called Rip Roar, who William believes killed his friend, Russell Rogers, and is working for the Rojas family. Rip Roar steals a laser weapon from an Army base and uses it to cause a devastating flood, though Supergirl, J'onn, and Dreamer are able to prevent mass casualties and capture the assassin. It is later revealed that Rip Roar is Rogers, knows Andrea, and is under the control of Leviathan instead. Meanwhile, Andrea successfully launches her new VR product, where Dey confronts a simulation of Andrea that he made. Andrea is visited by an elderly representative of Leviathan, Margot, who informs her about what happened to Rip Roar.

Flashbacks show how Andrea and Lena met, and how their friendship became strained. While searching for the acrata medallion, Andrea has her first encounter with Leviathan, who put her up to killing Governor Harper and Caroline O'Connor by telling her how the medallion works. To further their goals, Leviathan brainwashes Rogers into becoming Rip Roar to act on their behalf. In the present, Andrea is assigned to eliminate the captured Rogers, but her first attempt to break into the D.E.O. fails. After going to Lena for help, Andrea sets up a fake break-in for Supergirl to investigate while she raids the D.E.O. headquarters once again with psychic tech as the masked Acrata; making off with Rip Roar even in spite of Supergirl's intervention. During the raid, Supergirl discovers the assassin's connection to Leviathan. Andrea gives Lena the medallion and attempts to run away with Rogers, but a Leviathan operative kills him before another of their representatives meets with her. Though she says she does not have the medallion anymore, she is told that it merely activated her powers, which actually came from the darkness within her. Elsewhere, Alex and Lena independently continue to learn more about Leviathan.

Margot fails to get the medallion back from Lena, forcing Leviathan to take action. Meanwhile, J'onn begins to have visions of Malefic. When he asks his father's spirit for help, he suggests J'onn should attempt to bond with his brother, no matter the outcome. The bond is successful, and Malefic forgives J'onn. Back at the D.E.O., Brainy discovers Leviathan's location and travels there with Alex while Lena and Kara search for a weapon in the Fortress of Solitude to defeat the organization. Suddenly, they are attacked by Rama Khan, a centuries old alien and agent of Leviathan who can manipulate the Earth. While fighting him, Kara manages to suppress Khan's powers, forcing him to retreat. Afterwards, Lena admits to Kara she killed Lex, knew her secret before she told her, and rants about how she broke her trust and deserves to feel her pain. Lena ignores Kara's attempts to reason with her and leaves her trapped in kryptonite gas.

Alex and Brainy save Kara from the Fortress' trap. Alex tells Kara that Lena is beyond redemption, but Kara disagrees. Meanwhile, Andrea joins Kara and J'onn in fighting Khan while Lena prepares to mind-control all of Earth with Q-waves. In response, the D.E.O. has Malefic use his own Q-waves to repel them. Kara subdues Khan before Andrea seals him in a tar pit before they attack Leviathan's hideout. After breaking up the fight, Andrea flees just as Leviathan operative Gamemnae relieves Khan of his duties. When Lena and Hope are discovered, the latter takes the fall as Eve and is arrested. Later, Malefic decides to return to Mars, and the Monitor reveals to J'onn that he brought Malefic to Earth to test him for the impending crisis, which he passed by reconciling with his brother. Unbeknownst to anyone, the Monitor has resurrected Lex and is also preparing him for the crisis; fulfilling the latter's desire to become a hero in exchange for helping him with a favor involving Lena.

As the Crisis begins, Brainy detects an anti-matter wave approaching Argo City, so Kara warns her mother Alura Zor-El, her cousin Clark Kent, and his wife Lois Lane. The Kents narrowly send their son Jonathan off-world just as the wave hits Argo. Meanwhile on Earth-1, Harbinger brings Barry Allen, Kate Kane, Oliver Queen, Mia Smoak, Sara Lance, and Ray Palmer to Earth-38 and rescues the Kents. As Harbinger briefs the heroes on the Anti-Monitor, the Monitor raises a quantum tower to impede the anti-matter wave while the DEO and Lena work to evacuate Earth-38. After learning Jonathan ended up on Earth-16, Lois, Sara and Brainy leave to get him. In preparation, Oliver passes the mantle of Green Arrow to Mia, but when he learns Barry is fated to die, he argues with the Monitor over the deal they made last year.[a] The heroes fend off an army of shadow demons until the Monitor breaches them off-world. However, Oliver stays behind; sacrificing himself to ensure the exodus succeeds. On Earth-1, Lois' team returns with Jonathan before the Monitor brings a dying Oliver to share his good-byes. Nash Wells, now a "pariah" for releasing the Anti-Monitor, appears, announcing everything is doomed.

This episode begins a crossover event that continues on Batwoman season 1 episode 9, The Flash season 6 episode 9, and Arrow season 8 episode 8, and concludes on Legends of Tomorrow's special episode.

Following the Crisis and her Earth being merged with Earth-1, Kara adjusts to her new life on Earth-Prime when she discovers she is working for Lex, who is now the founder of the D.E.O. and Leviathan is no longer a public threat while J'onn restores their allies' pre-Crisis memories. Four alternate Brainiac-5's, who had survived the Crisis, suddenly appear on Earth-Prime. They are unsure of how it happened, though they know they are being targeted by the Anti-Life Equation. Nia discovers that one of them plans to bring back his Earth, which he trapped inside a bottle. However, she, Kara, and Brainy defeats the evil Brainiac-5, who makes peace with the team and decides to live in the bottled Earth until Kara and her team can find a way to bring it back. Before the other Brainiacs merge with Brainy to form the "Big Brain", the female Brainiac-5 informs him that in order to defeat Leviathan, he must secretly ally himself with Lex and sacrifice his friends and relationship with Nia to do so. Elsewhere, William voices his suspicions about Lex to Kara while Gamemnae visits Andrea under the alias of board member Gemma Cooper.

With Brainy's help, Lex breaks out a doppelganger of Winn Schott to attack a toy convention under the alias of Toyman. Just then, Winn returns from the future to stop his doppelgänger from changing his future. Kara, Alex, Winn, Nia and Brainy seek out J'onn, who has built a new base of operations called "the Tower" instead of going to the D.E.O. so he can get Winn up to speed on what happened before the Crisis. At the Tower, Nia attempts to use her powers to find Winn's doppelgänger, but instead sees Brainy turn into a white tiger. The team learn from a livestream that Winn's doppelganger plans to attack Andrea for ruining his father's reputation using robotic white tigers. Armed with this information, Kara, Winn, Nia and Brainy manage to stop him, but he gets caught in an explosion and seemingly killed. After saving Winn's future, Brainy tells him about his alliance with Lex. Unbeknownst to everyone, the alternate Winn's consciousness suddenly appears in the D.E.O.'s computers.

The D.E.O. discover the alternate Toyman used the Obsidian Lenses to upload his consciousness into their computers moments before his death so he can weaponize the Internet. Alex places the D.E.O. on lockdown while Winn and Supergirl head to the server room. When they get there, they learn Winn's father, the original Toyman's, consciousness was also activated as he wants to help defeat his son's evil counterpart. When Winn confronts his doppelgänger's A.I., he reluctantly allows his father to buy him time. He enters the codes and foils his counterpart's plans as both Toymen's consciousnesses are deleted. Winn returns to the future to become a heroic Toyman in his father's memory. Due to what she learned from Brainy, Alex resigns as the D.E.O.'s director, so Lex swears in Brainy while procuring a copy of the data he wanted in order to get them closer to Leviathan. Meanwhile, Lex tracks down Gemma to discuss a collaboration with Obsidian Tech to improve the Obsidian Platform. Won over, Gemma advises Andrea to take the offer. She later has Margot inform the Anointed One that LuthorCorp is in their clutches as planned. While in their loft, Kara and Alex are visited by Mxyzptlk.

Mxyzptlk offers to help Kara by traveling back in time so she can tell Lena her identity before Lex can and ensure their friendship turns out differently. After several failed attempts, Kara decides to tell Lena after the latter moved to National City. However, Ben Lockwood blackmails Kara into globally revealing her identity by kidnapping Lena before killing Kara's friends and family. Then, Mxyzptlk shows Kara a reality where she and Lena did not meet, but his powers stop working. Nia saves them from danger and brings them to meet Alex, J'onn, Winn, Kelly, Mon-El. Kara learns that Lena killed Lex before harnessing the 5th Dimension's energy for her Hope-Bots and getting Reign and a reprogrammed Brainy on her side. While her allies fight them off, Supergirl confronts Lena and Mxyzptlk looks for the Hat's namesake. Once he gets it, he undoes the reality. As nothing else worked, Kara decides to confront Lena as Mxyzptlk takes his leave; leaving a video about the day Lena and Lex started working together. Kara tells Lena that she can still help her, but will be forced to take action against her if she continues to help Lex.

Brainy informs Lex that Leviathan's members are from the same system as Krypton and that they need to find their version of Kryptonite. Supergirl thwarts an attempt on Andrea's life, so Lex assigns her to bodyguard duty so the Obsidian Platform's launch will go smoothly while pitching this idea to Gemma as a means of keeping her people out of the way. J'onn is informed of the energy that Supergirl saw during the attack and recognizes them as a Chlorophyllian's. Lena tests her program on Stryker's Island inmates, taking note when they develop vengeful feelings. Alex and J'onn find evidence that takes them to an abandoned farm where a Chlorophylloid named Todd resides. After being rescued by Supergirl, they find Todd dead and his wife Amy out for revenge on Obsidian Corp after they fired Todd for his virtual reality addiction. As Alex and J'onn rescue the workers, Supergirl successfully talks Amy down. With the danger averted, Andrea retrieves the Acrata medallion from her office. Lex visits Gemma to work out a deal, wherein he will get them something in exchange for meeting her people.

Nia's roommate Yvette is assaulted by a man named Gregory Bauer, a vicious transphobe who catfishes and assaults transgender women to try and force Dreamer into retirement. Using her civilian identity as bait, Nia nearly kills him as Dreamer until Kara talks her down, reminding Nia of her importance to people. Meanwhile, Alex and J'onn take on a case to rescue a man trapped in virtual reality.

Jeremiah Danvers has been found, but recently died. Alex lashes out at everyone, weary of mourning for him again. In her despair, she uses the VR Lenses to enter a fantasy where she is Supergirl. However, consumers in the virtual reality are slowly losing their grip on actual reality and believing it to be real as they develop red eyes in the real world. Alex starts to succumb to this, but is unable to use the fail safe to exit the VR world. Kelly is able to get Alex out. After learning of this danger, Andrea talks to one of her employees, a restored Eve.

Retaining his pre-Crisis memories, Lex takes note of the changes that were made while he continues his hunt for Leviathan. As part of his plans, he convinces his Leviathan double agent, Eve, to manipulate Amy Sapphire and Richard Bates as well as kill Jeremiah. After seeing Lena show sympathy to Kara, Lex tricks the former into believing Supergirl is using Myriad. As Lena leaves the Fortress of Solitude, a Morae follows her and releases a Sun-Eater. Malefic's computers detect it, prompting M'gann to return and confront it. With help from J'onn and M'gann, Supergirl shrinks the Sun-Eater. Unbeknownst to them, Lex locates the VR victims' bodies. As Kara and M'gann meet with William, they learn Lex rescued everyone and eliminated Margot. Gamemnae confronts Lex, but he persuades her to focus Leviathan's wrath on Supergirl. Following a discussion with his mother, Lex uses Lena's transportation watch to enter the Fortress of Solitude.

Supergirl fights against Rama Khan and Leviathan. Lex and Lena are forced to work together when Lena’s project fails to work and they get stuck inside a prison riot. Lex helps Leviathan against Supergirl. Alex and Kara meet with Pete Andrews, a man Malefic impersonated, to learn more about Leviathan. Rama Khan lets himself get captured so he can destroy the DEO's headquarters. Lena realizes she is becoming like Lex while beginning to question her own path, causing the latter to explode on her before Lena leaves. She comes to Kara's apartment to apologize for her actions. William follows Eve into an alley and is black-bagged.

Lena tells Kara what she knows about Lex's plans, and they agree to work together to defeat him and Leviathan. Dreamer has visions of Brainy while fighting Leviathan, which she later realizes were about his secret plans. Brainy, without Lex's involvement, formulates a plan to stop Leviathan by shrinking them into a container. While the team distracts Leviathan, Brainy secretly infiltrates their headquarters. Upon learning that Leviathan plans to use the Unity Festival, Supergirl enters it to persuade its connected users to disconnect from virtual reality. Brainy puts his plan in motion when J’onn draws Leviathan's agents away. Supergirl ends the Unity Festival while Rama Khan and two Leviathan members are contained, but a weakened Brainy is unable to stop Lex from taking the container, which he and Lillian plan to use. After working together once again, Kara and Lena start to reconcile. Gamemnae, enraged, sheds her human guise.

Lex Luthor brainwashes half of the planet into loving him using the Obsidian Lens and gains the combined powers of the bottled Leviathan members, intending on doing what the Anti-Monitor couldn't do; destroy all life on Earth and beyond, save only for his brainwashed followers. With the help of her team, Kara Danvers destroys Gamemnae by uploading the Anti-Life Equation into the nearest console. In order to take down Lex's satellites, Kara falsely offers herself up to Lex at the Fortress of Solitude. Despite Lex being depowered, he defeats Kara's friends and sends Kara to the Phantom Zone before being arrested. Meanwhile, J'onn J'onzz and M'gann M'orzz destroy the satellites. Afterward, Lillian Luthor visits Lex at the National City Prison, but Lena Luthor uses Myriad to wipe their memory of Supergirl's identity. As Acrata, Andrea Rojas secretly buys her father's shares in Obsidian in order to restore her company. J'onn and M'gann begin searching for people to aid them in rescuing Kara, including Jonn's brother Malefic, but to no avail.

In the Phantom Zone, Supergirl meets her father, Zor-El, who survived Krypton's destruction by sending himself into the Phantom Zone and saves her from the Phantoms. Meanwhile, Alex Danvers struggle to cope with her sister's disappearance, and is consoled by J'onn. Kara's friends find a benign vampire-like Transilvanian named Silas who once broke into the Phantom Zone, and they agree to work with him. However, due to the Crisis, the Zone fractured into an archipelago and they cannot locate Supergirl as easily. With Silas's help, Kara's friends open a portal to the Phantom Zone, but they are unable to travel through and several Phantoms escape. Meanwhile, Lex's trial ends in an acquittal after he discredits Eve and Lena as witnesses, portraying them as bitter women. Nia Nal and William Dey resolve to expose Lex's crimes through their journalism. Silas later contacts J'onn stating that one of the Phantoms evaded capture.

A Phantom escapee attacks Silas and attempts to overtake him, and M'gann is injured while fighting it. In the Phantom Zone, Zor-El is kidnapped by Kryptonian criminals and is sent to be sacrificed to the Phantoms. Kara is injured, though she is rescued by a depowered fifth-dimensional being named Nyxlygsptlnz, a princess who knows Mxyzptlk and was sent to the Zone by her father. Meanwhile, Lena locks Lex out of LutherCorp's systems and donates all of his funds to a children's hospital. In retaliation, Lex has Otis Graves destroy it and puts the blame on a project that Lena oversaw. Kelly Olsen helps Alex cope with her sister's disappearance, and Lena talks Brainiac 5 down from a plan to murder Lex. Lena later quits LuthorCorp. Kara finds that her wounds won't heal normally in the Phantom Zone, but Nyxly heals her after Kara helps her regain her magic. They rescue Zor-El, who reveals that Alura Zor-El built the Phantom Zone, and focus on making an escape plan using Nyxly's magic.

Lena creates a weapon against the Phantoms and a way to track Kara in the Phantom Zone using Kara's DNA, but Alex later forces her to re-calibrate the device to find the Phantoms' lair as it's the only way to rescue the stolen souls. Nia has visions of Kara and Alex in Midvale High, and helps Brainy process his emotions. In the Phantom Zone, Kara, Nyxly, and Zor-El search for a mirror that can transport them home, but Zor-El is attacked. Nyxly attempts to convince Kara to leave Zor-El behind, claiming that he has been hindering her progress like her own father. Kara refuses and Nyxly reveals that she was the attacker, plans to take revenge on her father, and plots mischief on Earth. While fighting, Kara starts a self-destruct sequence and smashes the mirror to block Nyxly's escape. Sentinel, Brainy, Dreamer, and J'onn release the collected souls, restoring Silas and the transformed Phantoms. In order to get more of Kara's DNA, the team must go back in time to when Kara was in high school.

In 2009 Midvale, with Alex away at college, Kara has been do-gooding with the help of Kenny Li (who is alive on Earth-Prime). Cat Grant tracks evidence of super-feats in Midvale for a Daily Planet story. Kara, Alex, and Kenny find Brainy and Dreamer immediately. At the same time, the poacher Professor Naxim Tork and his henchman Mitch arrive in a Bismolian ship to capture superpowered aliens for his menagerie. He plans to attract Kryptonians to a staged disaster. Kara and Dreamer use their powers to prevent the disaster, which Cat partially witnesses. She enlists a child with a small drone to investigate further. Kara resolves to break off with Kenny but then learns he has built her a "Fortress of Solitude." Brainy identifies Tork, but learns that their new activities have prevented him from being captured three days later in Uruguay by the DEO. Brainy and Dreamer track Tork down, but he captures them in a forcefield.

Kara eliminates the forcefield, and all three defeat the poachers. Brainy locks them in their ship and sets to fly them to Uruguay, but Cat observes this with her drone, finds the cloaked ship, and accidentally releases the poachers. Their interference causes Kara to be severely poisoned when she stops the meteor. When the poachers demand Kara, Kenny instead surrenders, who is taken on the ship along with Cat. Brainy, Dreamer, and Kara rescue Kenny and Cat, but also release Plutonian Land Sharks. Tork and Mitch flee, the ship becomes visible, and Kara is captured. Brainy and Dreamer travel back in time again to the first fight with the poachers, and Kara stows away on their ship. Dreamer destroys the drone, interprets her dream, and convinces Cat to quit the Planet and begin her media empire. Kara and Brainy defeat Tork and Mitch, sending them again to Uruguay. When the meteor arrives, Kara is only slightly injured and Brainy recovers her blood sample. Kara tells Kenny she will leave town for college, and invites Kenny to come with her, but he chooses to find his own destiny.

While escaping with Zor-El, Kara experiences a Fear Vision of her friends' deaths. Brainy and Nia return with Kara's DNA, J'onn transforms the Tower into a spaceship, and they head for the Phantom Zone while M'gann stays behind to defend National City. Kelly teaches everyone how to overcome Fear Visions, leading J'onn and Alex to argue over who is more suited to retrieve Kara. A Phantom breaches containment, causing everybody to experience Fear Visions. Alex sees herself getting infected by a Phantom and sacrificing herself to draw the Phantoms away. Lena sees a Kelpie, a mythical creature that drowns everyone onboard. Kelly sees her friends infected and doubting her strength. Nia sees Brainy being sucked out of the ship after failing to interpret her dreams. J'onn and Brainy are unaffected due to their alien natures, and are able to force the Phantom back into containment, ending the Fear Visions. Kara and Zor-El are rescued and return to Earth while Nyxly secretly stows away with them on top of the Tower.

The team celebrates Kara’s return, but Kara suffers repeated flashbacks from her traumatic experience. Zor-El joins Kara and Nia at CatCo, posing as Kara's uncle Archie. Kara visits William, who is now seeing someone else. As CatCo's ratings plummet, Andrea overworks Kara and William and snoops for information as Acrata in attempts to trash Lex and reclaim CatCo's spot, but later realizes that there's nothing she can do and apologizes. Zor-El joins Supergirl in putting out a fire from a fallen satellite at a large collection of garbage in the ocean. The garbage prompts Zor-El to combat Earth's environmental crises out of guilt for failing Krypton, so he uses a Kelex named Oscar. It is programmed to convert garbage into energy, but it malfunctions and becomes a giant trash robot. Brainy and Zor-El create a virus to destroy it. Afterwards, Zor-El leaves to reunite with Alura on Argo City, Kara talks to Alex about her time in the Phantom Zone, and Lena calls Nia saying that she interpreted her Fear Vision of the Kelpie and leaves to visit her birthplace. In the middle of the night, Nia awakens, saying Nyxly's name.

In a dream, Nia unsuccessfully tries to reach her late mother. Nyxly gets trapped in the dream and offers to bring Nia's mother to life for one day in exchange for her freedom, promising to return to the Fifth Dimension afterward. Kara, J'onn and Alex track explosives while Andrea continues urging Kara and William to get human interest stories about the Superfriends. Kelly is assigned to help an alien superpowered boy named Joey. His brother Orlando is in prison, and Kelly and Kara soon learn that his work release plan has been corrupted to use him and other superpowered aliens to steal parts for a dirty bomb. William and Kara identify the warden as the plotter, in league with Intergang boss Bruno Mannheim. Supergirl convinces Orlando and the other aliens to surrender. Andrea is pleased with William's live interview with Supergirl, defending the now-reformed work release program and Kelly covertly exposes the abusive nature of Joey's foster home. With Alex and James Olsen's support, Kelly plans to take on the role of Guardian.

Nyxly puts Nia into isolation for the day, where her mother chastises her for releasing Nyxly, but helps her understand and overcome her fear. Nyxly, left powerless, is captured by Naxim Tork's former partner Mitch, but he releases her and plans to impress Tork by capturing Supergirl. Mitch first finds an Edifarian engineering expert, Dr. Desmond Raab, to build a cryo-bomb capable of freezing everything within a mile and uses it on the Ormfell Building, a housing project to which Orlando would be able to bring Joey. J'onn stabilizes the building and Supergirl destroys the bomb with her heat vision, but this inadvertently recharges Nyxly's powers. Supergirl tries to persuade the city to not let Councilwoman Rankin turn the Ormfell Building into a tech complex, and succeeds by letting Orlando tell his story to the city council. As the Superfriends rescue citizens, Nyxly freezes Supergirl and begins destroying the building. As Nyxly gloats that Supergirl is powerless against magic, Supergirl summons Mxyzptlk.

Mxy and Supergirl escape to the Tower, where Mxy musically explains that Nyxly plans to gain unlimited power by assembling seven magical stones, which she'll use to exact revenge against her father, King Brpxz. Nyxly intends to imprison Mxy in a crystal, and she will find him immediately if he uses any magic. She terrorizes the city with a giant cat and a deadly Hell Dragon. Mxy surrenders to Nyxly, who enlists Mitch's help. Meanwhile, Lena arrives in Newfoundland and visits the hometown of her mother, Elizabeth Walsh, guided by a photo of her friends Margaret Bishop and Florence Abbott. Elizabeth is remembered as an evil witch and is blamed for the death of Margaret and her abusive husband by their daughter Peggy. With Andrea's help, Lena finds Abbott who reveals that their coven accidentally killed Bishop's abusive husband. Florence tells Lena that she also has magical abilities.

Earlier, Kelly sees the destruction of the Ormfell building and helps Orlando pull Joey out of the rubble. The overwhelmed hospital workers pay little attention to them, even though they are glowing strangely. Councilwoman Rankin, also glowing, intimidates a doctor into giving her an experimental treatment, allowing her to recover immediately and gain the ability to materialize objects. As the Superfriends are preoccupied with finding Nyxly, Kelly and John Diggle work to identify Rankin's strange abilities. Kelly fights Rankin as Guardian and grabs a piece of her hair, allowing Brainy to learn how to stop her. He also improves the Guardian suit and tells Kelly that even the 31st century has inequality and oppression. Guardian uses Brainy's device to return Rankin's stolen 5th dimensional energy and she is arrested. Meanwhile, Lena begins studying magic in Newfoundland but rushes back to help her friends and finds a magic book from Florence.

At the Fortress, Kara and Lena learn about the Totem of Courage from Vita, a simulation of an eccentric Kryptonian witch. When someone activates it with a magic word, they must revisit a time when they lacked courage, gaining its power when they succeed in this trial. Supergirl disrupts Nyxly's theft of the totem in the form of a slingshot that David used to slay Goliath and blasts it with her heat vision before Nyxly can escape, leaving Supergirl and Nyxly with half each. This event enhances the courage of everyone at the scene: a shy scientist is emboldened to harness lightning, Sentinel becomes reckless, J'onn is distracted by being able to express his feelings, and Brainy dares to make inaccurate predictions. Attempting the trial, Kara revisits her emergence as Supergirl, but fails, and Nyxly revisits her defeat by her father, finally succeeding by expressing her anger at her brother's betrayal. Kara's half of the totem tries to rejoin the other. Kara has Lena release it because she can only stop a catastrophic lightning storm with her team restored to their normal personalities. This works, but Nyxly now has the totem and looks for more. Vita suggests to Lena that a previously unknown Earth witch might be able to help.

William asks to be embedded with the Superfriends, agreeing to keep some operational details secret. Nyxly finds and takes the Totem of Humanity (a Bodhi charm) and activates it, causing everyone in range to join a brawling mob. Lena first fails to use her mother's spell, but William helps her with a cooking analogy. The spell works, but makes the area of violence larger. Supergirl convinces her do this again, knowing through her psychic bond that Nyxly is overwhelmed by feelings of compassion. Unable to kill a guard to obtain the Totem of Hope, Nyxly abandons the Totem of Humanity, ending the violence. Supergirl recovers it, but Nyxly starts off after the others while planning to reclaim the Totem of Humanity at a later date. Meanwhile, Kelly checks on the new foster parents of Esme, the girl from Joey's former group home. They seem nice. When they are trapped by the mob, they discover that Esme can breathe fire when faced with an Infernian attacker. They put Esme outside to protect themselves from the mob, before Guardian and Sentinel rescue her. They decide to become Esme's own foster parents and learn about her kind's true powers.

Esme's new life with Kelly and Alex is soon complicated by her Dryalian ability to acquire superpowers from anyone nearby. They let her experience their friends' powers, but overdo it to the point where she says she should go back. With the help of a Truth Seeker, they reassure Esme that they will never abandon her. Nyxly identifies the Totem of Hope, and find that in order to use it they must "inspire hope brighter than the sun". Thinking this a job for Supergirl, Nyxly plans to extort both the Hope and Humanity tokens by taking William hostage. Nyxly's activation of the totem exacerbates a dispute between Kaznia and another nation, leading to nuclear war. Supergirl disarms both nations, passing her test by inspiring hope, and with William's help rescues him and gets all three stones. She sends the Hope totem into the sun, so that Nyxly can never unite all seven totems. Nyxly receives a gift from a "secret admirer" which contains a special watch that forms a Lexosuit around her.

Following the advice of her suit's A.I., Nyxly heads into a laboratory so that she can access the Dream Realm and claim the Dream Totem. A Nightmare Monster is released, forcing the Super Friends to quarantine it in a forcefield dome with people trapped inside. Nia follows her dream vision to a university and the office of Dr. M. Revée, who is actually her sister Maeve. They work together to get into the Dream Realm, but Maeve tries to steal the Dream Totem and the oracle deems her unworthy. Nyxly steals it. Meanwhile, Kara resolves to end tensions between Kaznia and Corto Maltese, but misses interviews with a Kaznian negotiator and the nation leaders due to hostility in the dome and the monster. She hands the interviews to William and quits, and publicly apologizes as Supergirl. Though Nia considers Maeve's acts unforgivable, she does give her a second chance. Elsewhere, Nyxly places the Dream Totem in the gauntlet, causing Lex to appear.

Lex reveals to Nyxly that he travelled to the future, where they fell in love but that she died after achieving her revenge. The Superfriends bait Nyxly using a fake Love Totem and Lex rescues her. Nyxly rebuffs him, so he captures Mitch and uses him in a plan to attract her. J'onn unlocks the Courage Totem, revisiting the time he failed to protect his daughters. Nyxly finds the Love Totem, but it disappears during a fight with the Superfriends and asks for Lex's help. It reappears when Alex and Kelly propose to one another, but is destroyed in another fight against Lex and Nyxly. With Lena's help, Kara uses the Humanity Totem against Nyxly, but Lex rescues her and retreats. Afterwards, the Superfriends celebrate Alex's and Kelly's engagement and Brainy contacts the Legion of Superheroes. Meanwhile, Andrea plots to expose Lex's partnership and as Acrata, steals a journal from Lex. William secretly meets with Otis Graves. Lex gives Nyxly a recreated Hope Totem as a new Love Totem appears as a tattoo on Esme's neck.

The Superfriends locate Mitch's ship in cislunar space. J'onn and Supergirl defeat Nyxly and Lex, who activate the ship's self-destruct and flee through a portal (saving Mitch at the last minute). Andrea leaks Lex's love for Nyxly while using William's name. Supergirl obtains the new Hope Totem at the last minute. All seems well, and Kelly and Alex host their bachelorette party, leaving William to mind Esme at the Tower. There Brainy reveals his message from the 31st century, that he can only save the Coluan people by returning there and end his individual existence. Nyxly locates the Love Totem, Lex disarms the Tower's defenses, and they take Esme, with Lex shooting William dead on his way out. Before dying, William recorded the final moments and mailed it to Andrea which leaves her devastated. The rest of the Superfriends find William dead.

Lex offers to exchange Esme for the other totems. The Love Totem tattoo begins losing its petals, but Nyxly refuses to harm Esme despite Lex's warning that this is how she fails. Lillian attempts to break up Lex and Nyxly. Lena catches Acrata in the Tower, but reminds her that she can change for the better. Kara finds the Destiny Totem in Prague and sees Lex and Nyxly all-powerful, but Alex takes it and the other totems. Lex extracts the Love Totem, but this angers Nyxly and she takes the totem and returns Esme. Brainy and J'onn hijack a satellite to refocus the Sun's energy into Kara to make her invincible, but stop when humanity is harmed by the loss of sunlight. The Allstone is formed, but Esme shatters it and Nyxly, Lex, and the Superfriends fight for its fragments. Nyxly mortally wounds Lillian and she and Lex depower humans in order to keep fighting each other.

Lillian tells Lena to fully own her power and dies from her injuries. Kara reassures the people of humanity and they reclaim their power, weakening Lex and Nyxly. The Superfriends, joined by Acrata, Orlando, Mitch, Eliza Danvers, Mon-El, Winn Schott, and Jimmy Olsen, fight Lex, Nyxly, and manifestations of Overgirl, Red Tornado, Metallo, Parasite, the Hell Dragon, and the Nightmare Monster. Lex opens a portal to the Phantom Zone. Since they feed on fear and their supposed victims stand strong, the Phantoms drag Lex and Nyxly in. Days later, the Superfriends attend William's funeral and reform the DEO. Mon-El tells Kara that he will no longer be able to return to the past to see her, due to his responsibility with The Legion. Three weeks later, Cat Grant re-buys CatCo and offers Kara a job as her editor-in-chief. Alex and Kelly get married, and Brainy decides to stay in the present with Nia. Winn hints that J'onn and M'gann have a son in the future. Cat and Lena convince Kara to accept the job and end her double life by revealing her identity as Supergirl to the world so she can live a more full life as one person.

The origin of the Flash. An accident gives police crime lab expert Barry Allen awesome powers of speed, and he vows to use them to bring his brother's murderer to justice. But first, Allen must learn to control his sudden, remarkable talents. Dr. Christina "Tina" McGee, who works for S.T.A.R. Labs, helps him with this.

Tina's former colleague is the main suspect when the bodies of murdered homeless people mysteriously disappear from crime scenes. He needs subjects for genetic-engineering research.

A crooked D.A. discovers the Flash's civilian identity and uses that information to extort him into becoming his secret accomplice.

Guarding a priceless exhibit has the police stretched thin, a situation which a criminal mastermind exploits citywide with several thefts.

A mad scientist implants a device in the Flash's brain and gains remote control of his powers in order to stop a witness from testifying against a drug lord the scientist is working for.

Ex-cop Henry Allen dismisses Barry's modern police techniques until his son captures an escaped con targeting Henry.

A 1960s drug icon who faked his own death and went into hiding reasserts himself by unleashing a new addictive designer drug on the world.

Barry puts together bits of metal found at crime scenes and discovers that they form a neo-fascist group's medallion, with Lt. Garfield as the group's next target.

The Ghost controls the airwaves, tapping into video feeds just as he did back in 1955. The Nightshade, a crime-fighter of that era, resurfaces to fight him with the Flash joining him.

A criminal who has developed a cloaking device renders himself invisible and establishes a deadly vendetta endangering S.T.A.R. Labs and Central City.

The Flash must race against the clock and the electric chair in almost real time to prove the innocence of a jazz saxophonist who was convicted of murdering his famous wife.

The hunter becomes the hunted as James Montgomery Jesse, a schizophrenic killer being pursued by Megan Lockhart, commences to stalk her instead. Inspired by the Flash, the criminal dons a flashy outfit and calls himself the Trickster.

Tina embarks on a crime spree with an all-girl gang after a bio-feedback experiment yields disastrous results, and her first target is the Flash.

The Flash helps a mother protect her child against her dangerous husband, who wants the child only for its genetic potential.

While pursuing his brother's killer, the Flash is sent ten years into the future, where Nicholas Pike is the mayor of Central City and any mention of the Flash is against the law.

The Flash and the Nightshade team up once again to stop a murderous vigilante who has taken the Nightshade's name.

On the hottest day of the year, four gangsters are found frozen to death. They are the victims of a notorious hitman known as Captain Cold, and his next target may be the Flash.

A scientist uses the Flash's blood to clone Barry Allen, and the clone decides to assume Barry's identity. Wearing a Blue version of the Flash suit, the clone is named "Pollux" after the Greek deity from legend.

Sam Scudder, a criminal genius who uses mirrors and holograms to commit his crimes, hunts down his double-crossing partner, who has found refuge with one of her old high school friends - Barry Allen.

When bodies begin disappearing from the police morgue and a gang of thieves start putting people to sleep, it falls to the Flash to save the victims and clear Barry Allen's name at the same time.

A conscience-stricken android seeks the Flash's aid to avoid being programmed as the perfect assassin.

James Jesse is preparing to go on trial for the crimes of the Trickster, but with the help of his sidekick, Prank, and a brainwashing device, he soon enlists the Flash's assistance in passing judgement on Central City.

Barry Allen, a forensic crime scene assistant for Central City Police Department, is struck by lightning during a storm that is created after a particle accelerator from S.T.A.R. Labs explodes. In a coma for nine months, Barry awakens in S.T.A.R. Labs, having been placed in the care of his scientist idol, Dr. Harrison Wells, along with his assistants, Dr. Caitlin Snow and Cisco Ramon. Barry quickly learns that he can move at extraordinary speeds, and that there were other "metahumans" created from the explosion. One of them, Clyde Mardon, is robbing banks with his ability to control the weather. In order to stop Clyde, Barry is outfitted with a suit, designed by Cisco, that can withstand his high speed of movement. He tracks down Mardon and with the help of Detective West, who learns of Barry's abilities, Barry is able to stop Mardon. With his new powers, Barry vows to find out who killed his mother when he was a child, believing him to be another metahuman who has similar abilities of speed as he. Elsewhere, in a secret room at S.T.A.R Labs, Wells reveals he is not paraplegic, while reading a newspaper from the future concerning Barry's fate as the Flash.

With help from Cisco, Barry begins using his abilities to stop minor crimes and help citizens across the city. As Barry begins to push himself more and more, he begins to develop debilitating side effects. While assisting Iris on a school assignment, Barry witnesses a robbery by a crew of men, but faints while trying to stop them. The S.T.A.R. Labs team determine that Barry is becoming hypoglycemic from the use of his abilities due to a sped-up metabolism and needs to ingest more calories to maintain his energy level. The team eventually learns that the robbers are actually one man, Danton Black, who has the ability to create clones of himself. Black wants to kill his former employer, Simon Stagg, who stole Black's cloning research. With encouragement from Joe, Barry goes after Black and successfully stops him from killing Stagg. However, Black commits suicide to prevent being captured. Afterward, Barry accepts Joe's help in finding out who really killed Barry's mother. Later, Wells visits Stagg, who has already become obsessed with the Flash after witnessing his powers and plans to exploit him as he did to Black. To protect Barry, Wells kills Stagg.

As the police investigate the murder of one of the city's crime families, Barry suspects that the killer may be a metahuman who can control poison gases. As Barry and Joe work to discover the killer's identity, Dr. Wells and his team work to retrofit the particle accelerator into a prison specifically for metahumans where S.T.A.R. Labs can begin to find a way of reversing their mutations. This brings up difficult feelings and memories for Dr. Snow, whose fiance, Ronnie Raymond, was killed when the accelerator exploded. Following another murder, Barry locates the killer, Kyle Nimbus, but is unable to subdue him. Barry discovers that Kyle does not control gases, but literally transforms his body into them. The team learn that Joe, who was the lead detective in the original case, is Kyle's next target. Barry races to Iron Heights Prison in time to save Joe's life. Barry forces Kyle to overexert himself so that Barry can apprehend him without Kyle turning into mist. The team lock Kyle into a custom cell that is able to keep him from escaping. In a flashback to when the accelerator explodes, Dr. Wells is seen going into his hidden room and viewing a surveillance video of Barry getting struck by lightning in his lab.

Dr. Wells begins testing Barry's powers by forcing him to perform multiple tasks at superspeed. In the middle of the tests, a group of men attempt to hijack an armored truck carrying a priceless diamond. Barry races over and stops the crime, as well as identifying Leonard Snart from a set of police mugshots. Felicity Smoak arrives to check on Barry, after learning that he woke from his coma. Happy to see Felicity, Barry introduces her to his friends at S.T.A.R. Labs. To combat the "Streak", Snart acquires stolen tech from S.T.A.R. Labs, which includes a cryonic gun. Cisco reveals to Barry that he created the gun as a fail-safe against Barry should he become a killer like the other metahumans they encountered. Felicity helps the team locate Snart, who sets a trap for Barry. Cisco, Caitlin, and Felicity arrive in time to save Barry, and Snart is able to escape. Later, Snart tracks down his former partner, Mick, who has an affinity for fire, and offers him a place by Snart's side taking back Central City from the masked superhero.

A new metahuman appears in Central City, with the ability to turn anything she touches into an explosive. Barry is able to discover that the metahuman, Bette Sans Souci (Kelly Frye), is a former military explosives expert who was changed by the particle accelerator when it bonded bomb shrapnel to her body on a cellular level. As General Wade Eiling hunts for Bette, Barry brings her to S.T.A.R. Labs where the team explains to her how she got her powers. Unfortunately, they cannot reverse the process. While the team is away, Dr. Wells convinces Bette to kill Eiling so that he cannot exploit any metahumans. Barry races to stop her, but Bette sets off several bombs around Eiling and his men. Eiling manages to shoot Bette, which causes her body to turn into a massive bomb. Barry speeds off with Bette's body and drops it in the river to save the city from the explosion. General Eiling visits Dr. Wells, demanding that they work together, as they did in the past, to collect the metahumans. Dr. Wells refuses and warns Eiling to never return to S.T.A.R. Labs. In a flashback set five years in the past, Dr. Wells tells Eiling he is putting an end to their experiments. After Eiling leaves, Wells walks to a cage and tells Gorilla Grodd that he has plans for him.

Iris is visited by the Streak, who again pleads with her to stop writing about him. Before he can finish, Barry speeds off to stop a car thief. Barry confronts the thief, but when he hits him the thief's skin turns to steel and Barry breaks his hand. Barry runs back to the lab before he can be hurt further. The thief is identified as Tony Woodward, who was Barry's childhood bully. Barry and the team discover Tony's hideout, and Barry rushes in without a plan to defeat him. Tony gets the upper hand again and Barry is beaten up and left for dead. Back at the lab, Cisco determines that if Barry can hit Tony at over 800 mph at the right angle, then he can create enough force to compromise Tony's metal structure. Tony kidnaps Iris and demands that she write about him. Barry arrives and successfully hits the speed necessary to temporarily disable Tony's abilities. Afterward, Tony is locked away at S.T.A.R. Labs, and Iris renames her hero "The Flash". Meanwhile, Joe is visited by the metahuman that killed Barry's mother, who steals the case file and threatens Joe to drop his investigation.

Dr. Wells returns to his secret room, where it is revealed that he has been documenting Barry's growing abilities, and using his computer to look at events in the future. Barry arrives at a crime scene where the victim was murdered via electrocution, and charred beyond all recognition, suggesting a metahuman was involved. While investigating the victim's identity, the team identifies a power drain in the city. When Barry arrives he is attacked by Farooq Gibran, a man who has the ability to siphon electrical energy. The attack drains Barry of his speed, and when Wells checks his secret computer it reveals that there are no references to Barry or "The Flash" in the future. Wells believes that Barry's body just needs an electrical jumpstart, and Farooq arrives at the lab while the team is attempting to help Barry. The process does not appear to work, but Wells quickly realizes that Barry's problem is psychological. When Farooq catches up to the team and Dr. Wells' life is in danger, Barry overcomes his fear, connects to his speed on a cellular level and stops Farooq. Later, Dr. Wells sees that the timeline is back on track, and takes a sample of Farooq's blood to determine how he was able to drain Barry's abilities.

A new metahuman, Roy Bivolo, shows up with the ability to send people into an uncontrollable rage, and uses his ability to rob the Central City bank. The police track him to a warehouse, where he uses his abilities on a cop to facilitate his escape. Barry arrives in time to save Joe, but is almost injured himself before Oliver Queen, as the "Arrow", arrives to stop the cop. Later, Oliver informs Barry that he and his team are tracking a killer who uses lethal boomerangs. Barry and Oliver agree to team-up and catch each other's targets. Oliver tries to teach Barry to be more mindful of his surroundings, but Barry decides to go after Bivolo by himself. Bivolo uses his abilities on Barry, but because of Barry's powers it makes the effects last longer. Oliver tries to stop Barry, and the two engage in a fight. Oliver manages to wrangle Barry long enough for Dr. Wells and Joe to use colored strobe light to reset Barry's emotional state. Afterward, Barry and Oliver capture Bivolo and place him in the prison at S.T.A.R. Labs.

The metahuman that killed Barry's mother returns, killing two guards at Mercury Labs in search of the company's work in tachyon particles. Barry witnesses the man in yellow, and engages in a high speed fight around the city. The man in yellow insinuates to Barry that they know each other before speeding off. Meanwhile, Eddie asks Iris to move in with him and Ronnie is revealed to have survived the particle accelerator explosion, but does not remember who he is and has the ability to burst into flames. Barry confesses his love for Iris before the police and S.T.A.R. Labs use the tachyon particle technology as bait to lure the man in yellow into a trap. The man in yellow escapes and attacks Dr. Wells and the police before engaging in a second fight with Barry. Ronnie appears and blasts the man with flames before both flee the scene. Later, Dr. Wells enters his secret room and unveils the same yellow suit as the man that they captured, placing the stolen tachyon technology on the suit's chest.

As Barry works on improving his speed through various training exercises, Leonard Snart returns to Central City with the freeze gun and a new partner, Mick Rory, to set a trap for the Flash. Barry discovers his plan, and agrees with Dr. Wells to not engage Snart in the hope that he goes away and no one gets hurt like the last time. When the Flash fails to show, Snart and Rory, who now has a gun that can emit absolute hot temperatures, kidnap Caitlin to force Barry out of hiding. Cisco and Barry realize that if they can get Snart and Rory to cross the streams of their respective weapons it will cancel out the effects. The Flash meets Snart and Rory in the middle of a city for a showdown, exposing himself to the media. After multiple failed attempts, Barry eventually gets them to cross the streams with Eddie's help, successfully damaging the weapons and disabling the criminal pair. While in transport to Iron Heights Prison, Snart and Rory are broken out by Snart's sister. Meanwhile, Caitlin investigates the cause of Ronnie's transformation.

While home, Dr. Wells receives a threatening call from an unidentified person before having to use super speed to move out of the way of his glass ceiling shattering around him. Wells informs Barry and the team that the caller was Hartley Rathaway, a former protégé. Hartley begins attacking his family's business with sonic blasts, and when Barry arrives to stop him Hartley reveals that he knows the secret Dr. Wells is hiding. Dr. Wells reveals that Hartley warned him that the particle accelerator could explode ahead of time, but Wells chose to risk it for the potential rewards. Cisco discovers that Hartley intentionally got caught so he could steal information from S.T.A.R. Labs' computer that would allow him to identify the frequency of Barry's molecules so he can kill him. Barry triggers a trap set by Hartley, which starts shredding Barry's organs. Dr. Wells taps into a satellite and sends an alternative frequency to disable Hartley's weapons. Later, Joe has Eddie start an investigation into Dr. Wells. Hartley, imprisoned back in the particle accelerator, reveals to Cisco that he knows where Ronnie is and how to save him. In his secret room, Dr. Wells uses the tachyon technology to temporarily recharge his speed force energy.

A woman with the ability to teleport to any location she can see breaks into Iron Heights prison to free her boyfriend, Clay Parker. Barry finds residual DNA particulates all over the scene and when analyzing it at S.T.A.R. Labs the team identifies the woman as Shawna Baez. To help Barry, Henry Allen tracks down leads in Iron Heights and finds out that Clay owed money to a local crime boss, who was also planning a major heist. Barry learns the location of the heist, finding Shawna and Clay robbing an armored truck. Barry is able to capture Shawna after removing all the lights in a tunnel, effectively making her unable to teleport without being able to see where she is going. Cisco goes to Hartley to find out more about Ronnie; Hartley reveals that Dr. Stein, who developed research into a F.I.R.E.S.T.O.R.M. project focused on transmuting elements, was at S.T.A.R. Labs the day of the explosion. Hartley reveals that during the explosion Ronnie and Dr. Stein merged, before he escapes Cisco's custody. Later, Barry and his father discuss the Flash, with Henry insinuating he believes Barry is the Flash. Elsewhere, two city workers are attacked by the gorilla, Grodd, in the city's sewer system.

The team attempts to track Ronnie's whereabouts after he injures a scientist. Knowing that Dr. Martin Stein is in control of Ronnie's body, they use his wife to talk Stein/Ronnie into coming back to the lab for testing. Meanwhile, Joe enlists Cisco's help to identify who murdered Barry's mother. Cisco discovers an old mirror left in the former Allen home that captured images from the night of the murder, and Joe finds blood from two people behind some new wallpaper, one of whom was likely the killer. Joe asks Cisco to compare the blood to Dr. Wells', but Cisco refuses to believe Dr. Wells is involved. Dr. Wells discovers that Ronnie and Dr. Stein's atoms are in conflict, and if it continues they will become nuclear. Dr. Wells determines that a component of the tachyon device recharging his speed could be converted to a quantum splicer to stabilize Ronnie's body and separate the two personalities. Dr. Snow uses the device; Ronnie's body still goes nuclear, but safely away from the city. The explosion alerts General Eiling, who orders a team to recover "Firestorm". Cisco runs the blood samples and informs Joe that while neither is from Dr. Wells, one is from an adult Barry.

Barry and Caitlin investigate the explosion and find Ronnie and Dr. Stein have separated. General Eiling investigates the crater left by Ronnie and Stein's explosion, and realizes that "Firestorm" has separated. Joe shows Barry the images from the night his mother was killed, and Barry learns that a future version of himself was there trying to save his mother. Barry talks to Dr. Stein and learns about the possibility of time travel. Dr. Wells visits General Eiling, who reveals that he knows Barry is the Flash and that he wants the F.I.R.E.S.T.O.R.M. project. Dr. Wells gives up Dr. Stein, who is tortured by Eiling until Ronnie shows to save him. Ronnie and Dr. Stein are forced to reunite to survive Eiling's military onslaught. Merging properly this time, Ronnie and Dr. Stein work together to control the Firestorm Matrix within them, gaining enough control to be able to merge and separate on command. The pair decide to leave Central City to stay ahead of Eiling and learn more about their new powers. The Reverse-Flash kidnaps Eiling and brings him to the sewers. He reveals himself to be Dr. Wells, and allows Grodd, who is displaying psychic abilities, to drag Eiling deeper into the sewer.

Mark Mardon, who has the ability to control the weather, returns to Central City to avenge the death of his brother Clyde and sets his sight on Joe. Cisco begins to believe Joe was right about Wells, so he rechecks the containment field that had failed to hold the Reverse-Flash. He discovers that the Reverse-Flash seen in the containment field was only a hologram. Wells arrives and reveals himself to be Eobard Thawne, a man from the future who came back in time to kill Barry but killed his mother instead, and has since been stranded in the present day. Wells also explains that he is pushing Barry to get stronger so that he can use Barry's powers to return to his time, and he murders Cisco to protect his secret. Mark kidnaps Joe and forces him to watch as Mark sends a tsunami into the city in order to kill Iris. Barry is forced to reveal his secret identity to Iris in order to save the city. Barry runs back and forth across the coast line to create a barrier against the tsunami, but he runs so fast that he creates a time warp and travels back in time to when Mark first returned to Central City.

The Flash learns that Captain Cold and Heat Wave have returned to Central City, and that Snart has brought along his sister Lisa to help wreak havoc on the town.

Barry and Joe go after terrorist Axel Walker, who goes by the name Trickster. Axel sets a diversion for the Flash so that he can break James Jesse, the original Trickster from 20 years prior, out of prison. James and Axel attempt to extort wealthy patrons by poisoning them and ransoming the antidote. When the Flash arrives, the Tricksters fit him with a bomb that will detonate if he stops moving. Dr. Wells coaches Barry on how to vibrate his molecules so that he can phase through objects, which removes the bomb. Afterward, Barry provides an antidote to all the patrons, before capturing the Tricksters. Later, the Flash reveals his identity to Eddie, so he can help keep Iris from looking into Dr. Wells for her own protection, as Barry realizes that Wells is the Reverse-Flash. In flashbacks, after failing to kill Barry as a child, the Reverse-Flash escapes down the road only to lose his speed. Gideon informs him that travelling back in time has drained his powers. He removes his mask to reveal the real Eobard Thawne. Eobard stalks Dr. Wells and reveals the particle accelerator is not built until the year 2020. He then appears to kill Wells and steal his appearance and identity so he can develop the particle accelerator sooner and return to his timeline.

As Barry works in conjunction with Joe and Eddie to stop crimes across the city, an engineering professor is attacked and killed by a swarm of bees at the local university. While the team searches for a metahuman that can control bees, Felicity arrives with Ray, in his A.T.O.M. suit, looking for assistance to improve his suit. The team tracks another bee attack, but Barry is too late and is attacked by the swarm. The team captures one of the bees, which turns out to be a robot and their metahuman just a disgruntled scientist named Brie Larvan from Mercury Labs, who is targeting other former employees. Barry struggles with whether he can trust Cisco and Caitlin, not knowing if they are working for the Reverse-Flash or not. During the next bee attack, Barry goes after Brie while Ray, as the Atom, attempts to stop the bees from killing Dr. Tina McGee. Felicity taps into the wireless frequency for the bees to disable them, and Barry captures Brie. Later, Barry informs Caitlin and Cisco that Dr. Wells is the Reverse-Flash. Caitlin does not want to believe this, but Cisco does, revealing that he has been having "dreams" in which Wells kills him with super speed (as happened in the original timeline).

Barry and Eddie track a metahuman named Hannibal Bates, who can shape-shift into anyone he touches, but he takes Eddie's shape and frames him for murder. Later, Hannibal knocks Barry unconscious and assumes his form, but Dr. Wells realizes the truth and prevents Hannibal from killing Caitlin and Iris. While transporting him to Central City Police, Hannibal uses his powers to escape. Caitlin develops a serum to suppress Hannibal's power, allowing Barry to defeat him and clear Eddie's name. Meanwhile, Joe and Cisco decide to investigate the car accident scene in Starling City where Wells' wife Tess Morgan died, though Caitlin is unsure they are correct and believes they are going to ruin Dr. Well's reputation. With the help of Captain Quentin Lance, Cisco and Joe locate a buried corpse near the crash site. After a series of tests confirm the corpse is the real Harrison Wells, Barry, Caitlin and Cisco locate the imposter’s secret room at S.T.A.R. Labs. They find both the Reverse-Flash's costume and a newspaper article from the future concerning the Flash vanishing during a crisis.

While in Wells' secret room, Barry learns about his battle with the Reverse-Flash in the future, as well as key moments in his life that include marrying Iris, a promotion at the CCPD, and that he created the artificial consciousness known as Gideon in the future. The team regroups at Barry's home, where Barry explains his plan to convince Wells to confess to killing his mother. In order to trap Wells, Cisco reverses the polarity of his containment field to protect himself from Wells, while Caitlin films the interaction to capture Wells' confession. The trap fails, but Joe shoots Wells before he can kill Cisco. As Wells dies, his body transforms revealing himself to be Hannibal Bates. The real Wells calls the team, revealing that he was always aware of their actions because he had them under surveillance. Wells goes after Iris and Eddie, but Barry arrives forcing Wells to kidnap Eddie instead. Wells reveals to Eddie that he is really Eobard Thawne, Eddie's future relative. Flashbacks reveals the aftermath of Barry being struck by lightning, and Wells offering Joe to save Barry's life.

Barry scours the city looking for Eddie, but must take a break to stop a robbery at the gold reserve. When Barry confronts the would be thief, they are both disoriented by an unknown psychological attack. Back at the lab, Barry describes the attack to Caitlin and Cisco when Iris walks in, confronting Barry about being the Flash. The thief attacks again, but Barry is able to stop him. The thief turns out to be General Eiling, who was under the mind control of the gorilla Grodd. With a lead from Iris, Barry, Joe, and Cisco head into the sewers to look for Grodd. The trio realize that Grodd is getting smarter and larger, and during an attack Barry is knocked unconscious while Joe is kidnapped by Grodd. Cisco and Caitlin build Barry a device that will prevent Grodd from attacking him psychically. It works, but Grodd is too powerful and during a fight the device is damaged. Barry is able to fight off Grodd's psychic attack and trick him into jumping in front of an on-coming train. Elsewhere, Wells works on a device that will allow him to return to his time.

Cisco discovers that Wells has been supercharging his speed while he sits in his wheelchair, which is why he is so much faster than Barry. The particle accelerator is activated and the team realizes that Wells has been at S.T.A.R. Labs the entire time and he has repaired the accelerator. While investigating, Wells escapes but the team is able to find and rescue Eddie, who is disillusioned after Wells showed him that Iris marries Barry in the future. Eddie later tells Iris what he knows of her future and ends their relationship. Worried that when the accelerator reaches full power the metahumans imprisoned inside will be killed, the team decides to relocate them to the A.R.G.U.S. prison on Lian Yu. In order to set up a safe transport, Barry is forced to go to Leonard Snart for help. Snart agrees but only after Barry erases Snart's criminal record and history from the CCPD database. Snart sabotages the transport and allows the metahumans to escape. Wells arrives back at the lab just as the accelerator fully charges. Barry, Ronnie, and Oliver all meet outside to fight Wells. After each tries battling Wells individually, they coordinate efforts and Oliver finally stops him with a nanite injection that disables Wells' speed.

Barry visits Wells where Wells describes their relationship in the future, why he killed Barry's mother, and why he ultimately had to help Barry become the Flash. Wells also propositions Barry, requesting help creating a wormhole where Wells can return to his time, while also allowing Barry to go back in time to save his mother. Barry and the team are conflicted, as this could alter the timeline in an undeterminable way. Barry decides to go through with it, so Wells informs him that he will need to turn the particle accelerator on and then super speed at the right velocity into a hydrogen particle to create a wormhole. Barry will have less than 2 minutes to change the past, or the wormhole will create a black hole that could destroy the world. Barry successfully travels back in time, but his future self motions him not to save their mother. Instead, Barry identifies himself and reassures Nora that he is safe in the future before she dies. Barry returns and stops Wells from returning to his time. Before Wells can kill Barry, Eddie shoots himself causing Wells, as he is reverted back into Eobard, to be erased from existence. The team is unable to prevent the black hole from being created, and Barry super speeds into it in an effort to stop it.

Ronnie and Professor Stein turn into Firestorm and destroy the singularity, but at the cost of Ronnie's life. Six months later, Barry is now working on his own to avoid hurting any more of his friends and family; Cisco works in the police department alongside Joe and his metahuman task force, and Caitlin works at Mercury Labs. The city holds a ceremony honoring the Flash for his work in saving the city. At the ceremony, Barry is attacked by Al Rothstein whose strength and size manipulation prove too much for Barry to handle on his own. He is convinced by Joe and the others that he needs help in taking down certain metahumans and Barry defeats Al by allowing him to absorb too much radiation. In his dying breath, Al tells Barry that he was sent to kill him by someone named Zoom. Barry also receives a hard drive from Dr. Wells containing his confession to killing Nora that finally proves Barry's father's innocence. They throw a party where Henry tells Barry that he is not staying in Central City, so that Barry can focus on being the Flash. A mysterious man shows up at S.T.A.R. Labs, introduces himself as Jay Garrick, and declares the world in danger.

Jay Garrick, a mysterious man from Earth-2, appears at S.T.A.R. Labs with a dire warning about an evil speedster named Zoom, who is set on destroying The Flash. Barry and the team must decide if they can trust this stranger even as they face yet another powerful meta-human. Meanwhile, Joe must deal with a determined officer named Patty Spivot who wants to join his meta-human task force.

When Barry and the team find out Captain Cold has been kidnapped, they form an uneasy alliance with his sister, Lisa. However, Barry feels double-crossed when he finds out Snart is working with his father, Lewis Snart on a heist. Meanwhile, Joe is faced with a difficult decision.

Barry and the team look for another Firestorm match for Dr. Stein. When the team meets Jefferson "Jax" Jackson, Caitlin has her reservations about whether Jax is the right match for Dr. Stein. Iris surprises Joe West while Barry and Patty Spivot grow closer.

Barry learns a new breacher, Dr. Light, has come through the portal and sets off to capture her. Jay tells Barry that Dr. Light was not a threat on Earth-2 and that Barry can reason with her. However, during a fight with The Flash, she blinds him and drops some shocking news about Zoom. Meanwhile, Barry and Patty go out on a date.

As the team works to find a way to stop Zoom, Doctor Light escapes from her containment cell after Barry was hoping that she would help them stop Zoom. Instead, her Earth-1 counterpart, Linda Park, agrees to help the team by impersonating Doctor Light. Dr. Wells creates a speed dampening serum and the team stages a fight at one of the breaches in order to trick Zoom through. The attempt fails as Zoom knew what they were attempting. Instead, he goes after Linda before fighting Barry. Zoom is much faster and easily bests Barry, showing his defeated, unconscious body to the local news and the police station, before ultimately returning to S.T.A.R. Labs. Zoom stabs Barry with his hand, but Cisco shoots him with the serum, which hurts Zoom but still leaves him with enough speed to escape. Later, Wells reveals that Zoom has his daughter Jesse and he came to Earth-1 to stop Zoom. Barry wakes from his injuries and discovers that he can no longer feel his legs.

Barry manages to recover following his fight with Zoom, but is unable to use his powers due to the psychological trauma of Zoom exposing his beating to the city. Iris reaches out to Henry Allen, who returns to the city to help Barry overcome his fears. Cisco has a date with Kendra Saunders, but leaves after seeing a winged man in one of his vibes. Grodd returns, using scientists to steal various chemicals in the hopes of creating more gorillas with his level of intelligence. He later kidnaps Caitlin to help him with his plan. The team dress Wells up as the Reverse Flash in order to trick Grodd into thinking that his "father" is still alive. The plan works long enough for Wells to rescue Caitlin before they both escape. After Barry is fully recovered, they lure Grodd to one of the dimensional breaches and send him to a jungle sanctuary for gorillas that have been experimented on in Earth-2. Later, Cisco meets Kendra again, this time vibing and seeing Kendra as the winged figure.

Vandal Savage arrives in Central City looking to kill Priestess Shayera, who turns out to be Kendra, though she is not aware of it at first. Barry goes to Star City and enlists the help of Oliver and his team to protect Kendra until they can stop Savage. The team is visited by Malcolm Merlyn who informs them that Savage is an immortal who cannot be stopped. Later, Kendra is kidnapped by a winged man, but is rescued by Barry and Oliver who capture her captor. The man is Carter Hall, who tells them he was Prince Khufu in ancient Egypt and that he and Kendra are soulmates who have been connected for 4,000 years. The pair are destined to die, be reborn, and find each other in each lifetime. Carter also reveals that Vandal has killed them the last 206 lifetimes, each time growing stronger. Vandal locates the Staff of Horus, a weapon capable of killing Carter and Kendra, in Central City. After Kendra unlocks her abilities, the team decides to regroup in Central City to take down Vandal for good. However, Oliver encounters a family of mother and son from his past by chance, which may put their mission in jeopardy. Meanwhile, Caitlin and Harrison create a serum that will increase Barry's speed temporarily so that he can defeat Zoom.

Mark Mardon breaks James Jesse and Leonard Snart out of Iron Heights in an effort to team up to kill the Flash. Leonard declines and warns Barry as repayment for him saving Lisa. When Patty learns Mark is back in the city, she sets out to take revenge against Mark for killing her father years earlier. James and Mark place bombs hidden in Christmas gifts throughout the city, threatening to set them off in family homes if Barry does not sacrifice himself. Harry, Cisco, and Jay find one of the bombs and alter its magnetic polarity; they send it into one of the dimensional breaches, which causes it to attract the remaining bombs, removing them from the city. With them gone, Barry subdues Mark and James. Patty arrives ready to kill Mark, but Barry as the Flash talks her out of it. Meanwhile, Joe learns that his ex-wife was pregnant when she left and that he has an adult son named Wally, who later shows up at Joe's house. Elsewhere, Zoom visits Harry and agrees to release his daughter if Harry helps him steal Barry's speed.

As Dr. Wells struggles to try to find ways to increase Barry's speed, Cisco presents a new idea to slow Zoom down. Cisco tells the team about a metahuman, whom he has dubbed the "Turtle", who has the ability to stop the kinetic energy around him and thus slow everyone to a halt. After Barry fails to stop the Turtle at a diamond unveiling, the team sets a trap at a local art exhibit. Barry invites Patty, with the intention of telling her his secret, but the Turtle is aware of the trap and almost succeeds in killing Patty, before escaping. Later, the Turtle kidnaps Patty, in an effort to punish the Flash. The team tracks down the Turtle, and Barry is able to generate enough speed to move through the kinetic waves the Turtle creates to knock him unconscious and save Patty. Later, Patty tells Barry that she is leaving Central City, and Dr. Wells kills the Turtle while extracting a portion of his brain. Meanwhile, Joe struggles to develop a relationship with Wally, who has been street racing in an attempt to earn enough money to pay for his mother's medical bills.

The team discovers Turtle is dead, and Jay suspects Dr. Wells is responsible. Meanwhile, Cisco asks Harrison for help in controlling his vibing abilities. Harrison determines they are connected to Cisco's fear response, and he triggers a vibe which alerts the team that Eobard Thawne is back. Wells surmises that this version of Eobard is from a point in the future before he went back in time to kill Barry's mother, and was thus protected from being erased with Eddie's sacrifice. Retrofitting goggles to induce Cisco's vibes, the team learns that Eobard is planning to use tachyons to return to his future. Barry arrives and destroys Eobard's tachyon machine. After a race around the city, Barry stops Eobard and imprisons him at the particle accelerator. However, his capture causes a rupture in the timeline that threatens to kill Cisco, so Barry is forced to send Eobard back to the future to save his friend. Meanwhile, Patty discovers Barry is the Flash, but when he refuses to acknowledge it, she chooses to leave the city. Caitlin tries to find a cure for Jay's illness.

Right before the particle accelerator explosion, Joey Monteleone was thrown into a tar pit and left for dead. Sealed away, he is freed two years later with the ability to turn his body into tar. He sets out to get revenge on those who attempted to kill him. Meanwhile, Dr. Wells creates a device to syphon Barry's speed energy and attaches it to his suit. He and Barry also successfully find a way to close the breaches of Earth-2. When Barry goes after Joey, the device works, and permanently steals a portion of Barry's speed, slowing him down. Wells gives the energy to Zoom, who demands the rest. While going after Joey a second time, Iris is injured when Barry is too slow to save her. Watching Barry wrestle with the guilt of Iris' injury, Wells confesses. Wells pleads his case, asking to be returned to Earth-2 and have Barry seal the breaches so Zoom cannot re-enter. After stopping Joey with an invention of Wells', Barry realizes that Wells was only trying to save his daughter, which the rest of them would have done. The team informs Wells that he will return to Earth-2, but that Barry and Cisco will be going with him to save his daughter.

Before heading to Earth-2, Barry closes all but one of the breaches so that Zoom has no other way to travel between the parallel Earths. Using the last breach at S.T.A.R. Labs, Barry, Cisco, and Dr. Wells travel to Earth-2, but there is a surge of energy that de-stabilizes the breach. The trio will be stuck in Earth-2 until Caitlin and Jay can stabilize the breach again. Barry meets Iris and Joe of Earth two and Iris works for the CCPD and Joe is a singer at a jazz bar. Barry decides to impersonate his Earth-2 self to get more information on Zoom. Barry is attacked by Earth-2's Caitlin and Ronnie Raymond, known here as Killer Frost and Deathstorm, agents of Zoom. In the attack, Joe is killed. Cisco attempts to help the police stop the pair, but he is confronted by his own evil doppelganger, "Reverb". Cisco understands that Reverb has great power and can control the nervous systems too and is amazed. Barry tries to rescue him but is stopped by Reverb and Deathstorm. Zoom arrives, kills Reverb and Deathstorm for harming the Flash, and then imprisons Barry alongside Jesse. Meanwhile, Jay reveals to Caitlin that he invented Velocity-6 on his Earth, and that it is the real reason why he lost his speed and is dying.

Zoom realizes that Dr. Wells has returned to Earth-2 and issues a demand to the citizens of Central City to locate him. Zoom attacks S.T.A.R. Labs looking for Wells and Cisco, but they manage to escape with the Earth-2 Barry. Wells, Cisco, and Barry update Iris on what happened with the Earth-1 Barry, so they all set out to find Killer Frost in the hope that she will lead them to Zoom. After a fight, Killer Frost agrees to take the team to Zoom. The team arrives to rescue Barry and Jesse, but Zoom shows up too. The team is able to escape while Killer Frost keeps Zoom frozen and unable to move, but a third, unidentified prisoner is left behind. On Earth-1, Caitlin creates "Velocity 9", a compound to temporarily give Jay his speed so that he can stop a new metahuman named Geomancer. After, Caitlin discovers that when Jay uses Velocity 9 the serum starts to cure his illness. Jay, Caitlin, and Joe stabilize the breach and allow Barry, Cisco, Wells, and Jesse to return, but not before Zoom kills Jay and pulls him back through the closing breach to Earth-2.

Wells, Cisco, and Barry agree not to discuss what happened on Earth-2 for fear of repercussions. While everyone tries to move on, the humanoid shark-monster that Wells stopped, known as "King Shark", escapes A.R.G.U.S. custody and heads for Central City to kill the Flash. John Diggle and Lyla Michaels arrive to warn Barry, which prompts him to look for King Shark and put a stop to him for good. Barry teams up with Diggle, Lyla, and the rest of A.R.G.U.S. to track King Shark, but he shows up at Barry's home looking for the Flash, tracking Barry's electrical field. A.R.G.U.S. arrives and forces King Shark to retreat. The teams attempt to trick King Shark into a trap, but the bait does not work. Barry forces King Shark to chase him out on the water, and when he is far enough he creates an electrified, underwater cyclone that subdues King Shark and allows A.R.G.U.S. to imprison him again. Later, Barry vows to open a breach back to Earth-2 to stop Zoom. Back on Earth-2, it is revealed that Zoom's real appearance looks exactly like Jay.

The Flash team work to train Barry to get faster so that he can stop Zoom. However, they hit a roadblock and decide to go out to have fun and decompress. While they are at a club, another speedster shows up and robs everyone before escaping. A Mercury Labs employee, Eliza Harmon, turns out to be the speedster, who developed Velocity-9 from samples Caitlin gave her to help with Jay's illness. Operating under the name "Trajectory", she invades S.T.A.R. Labs, imprisons Barry, and demands more V-9. After she threatens Jesse's life, Dr. Wells and Caitlin make more of the drug for Eliza, who then speeds off to wreak havoc on the city. Barry tracks her down and tries to talk Eliza into giving up. She refuses and injects more V-9 into her system before speeding off. Barry watches as Eliza's speed becomes so intense that her lightning turns blue and she disintegrates. Meanwhile, Jesse decides to leave the city to experience the world on her own. Based on what Barry saw from the overuse of V-9, the similarities between Zoom's speed and Jay's sickness, and Cisco's "vibe", the team concludes that Jay is Zoom.

Barry travels back in time to when Hartley Rathaway attacked the team, and changes places with his past self in order to have Dr. Harrison Wells/Eobard Thawne help him solve the Speed Force equation. However, after a Time Wraith follows Barry to the past, Eobard deduces Barry's deception and attempts to kill him. Barry is able to convince Eobard that his plan succeeds in the future, but in order to maintain it he must help Barry become faster. The wraith comes to the lab, where Caitlin and Cisco are forced to accept help from a captured Hartley to deter the wraith. Afterward, the Barry from the current time arrives, forcing an explanation of the time-travel event. Eobard provides the future Barry with the information needed to solve the formula so that he can return to his time. Before he leaves, Barry gives Caitlin and Cisco instructions to find a way to stop the wraith. As Barry prepares to make the jump through time, the wraith arrives, which forces the past timeline's Barry to intervene so his future self can return. Back in his time, Barry is confronted by the wraith again, but Hartley arrives with his sonic gauntlets and defeats the wraith.

Years earlier on Earth-2, a young Hunter Zolomon watches as his father murders his mother and is subsequently sent to the local orphanage. In present day, Barry tests the tachyon accelerator and is able to enhance his speed four times greater than normal. Barry decides to re-open a breach back to Earth-2, and he believes that Cisco's powers are the key to opening the portals. Meanwhile, Wells recounts how the particle accelerator explosion on his Earth created Zoom, an adult Zolomon, a convicted serial killer who was receiving electroconvulsive therapy during the explosion. Cisco opens a breach and Zoom immediately comes through, chasing Barry back to S.T.A.R. Labs. There, Barry uses images of Zoom's parents as a distraction to trap him, but Zoom manages to escape. Zoom kidnaps Wally and demands Barry's speed in exchange for Wally's life. Barry agrees, so Wells siphons all of his speed force and leaving Barry human. Zoom injects the speed force, and with his enhanced speed he kidnaps Caitlin before escaping.

As Barry adjusts to life without his powers, Wells decides to leave the lab to look for Jesse. Shortly after speaking with her, Wells is attacked and kidnapped by Griffin Grey, who demands that Wells find a cure for his metahuman abilities. Grey has superhuman strength, but he is also aging rapidly. Barry discovers that when Grey uses his super strength, he accelerates the aging process. Barry, Joe, and Cisco manipulate Grey into exerting his powers until he ages and dies as a weak, old man; his body then reverts back to its 18-year-old self. To fight Zoom, Wells offers to recreate the events that Barry gave his speed. On Earth-2, Hunter tells Caitlin that he kidnapped her because he is in love with her. Caitlin encounters her doppelganger, Killer Frost, who was captured by Zoom. Frost convinces Caitlin to help her escape, but then attempts to kill her. Zoom arrives and kills Frost, then warns Caitlin not to free the man in the iron mask. Later, Zoom decides to conquer other Earths in the multiverse, and he takes Caitlin with him back to Earth-1.

With Barry powerless, the team rigs a hologram of the Flash to stop crime around the city so that no one knows the truth. Wells again proposes recreating the particle accelerator explosion. Barry goes to his father, Henry, for advice, who returns with him back to Central City. Henry argues with Wells over his procedure for returning Barry's powers, concerned for his son's safety. Zoom and Caitlin arrive back on Earth-1, with Zoom declaring the city under his control. The Earth-2 version of Dante Ramon, "Rupture", arrives on Earth-1 looking to kill Cisco for killing his Earth-2 brother. Zoom sends Rupture after the police to send the city a message. Barry and the police stop Rupture, but Zoom arrives and kills the officers himself, and Rupture for failing. He then publicly announces the Flash's disappearance. Realizing that he cannot stop Zoom without his powers, Barry agrees to Wells' plan. During the process, Barry is seemingly vaporized, while Jesse and Wally are caught in the blast.

Jesse and Wally are found unconscious; Wally recovers, but Jesse remains in a coma. Meanwhile, Cisco has a vibe of Barry and realizes that he is still alive. Barry wakes up in his own bedroom and finds "Joe" downstairs. "Joe" explains what he really is: a physical manifestation of the Speed Force. "Joe" informs Barry that he cannot leave unless he catches a mysterious moving figure. Cisco and Wells create a path into the Speed Force so Barry can escape, but Barry chooses to remain so he can earn his powers back. As he pursues the figure, other Speed Force entities challenge Barry on what it means to be a hero, and how he cannot become the Flash again until he finally accepts his mother's death. Barry shares a moment with his "mother", which allows him to finally catch the moving figure - himself. His powers restored, and with help from Cisco and Iris, Barry returns to S.T.A.R. Labs to save the team from the reanimated corpse of Tony Woodward. Afterwards, Barry uses speed force energy to bring Jesse out of her coma. Across town, Zoom has assembled a metahuman army, which he plans to unleash on Central City.

Zoom's metahuman army wreaks havoc across the city. Barry puts out several fires and takes out some of the metahumans to help the police. Back at S.T.A.R. Labs, Barry displays a level of confidence in stopping Zoom that concerns the team, and each of them attempts to convince him to be more cautious. Caitlin returns to the team, but not without emotional trauma from being kidnapped. A metahuman begins attacking various buildings around Central City using a sonic blast. Barry confronts the metahuman, who turns out to be Laurel Lance's doppelganger, "Black Siren". She initially gets the upper hand, but Barry is rescued by Wally, who is trying to help out in order to repay the Flash. The team creates a sonic amplifier tuned to the frequency of Earth-2 natives. They discharge it and render all Earth-2 metahumans unconscious, allowing Barry to apprehend them all at once, although Zoom escapes. Later, Zoom returns and kidnaps Henry in front of the team. Barry races after them, revealing his identity to Wally, and is forced to watch Zoom kill his father.

Zoom comes to Barry and demands a race to determine who is faster, threatening to kill everyone Barry loves if he refuses. Wells realizes that Zoom stole a magnetar from Mercury Labs that will allow him to destroy every world in the multiverse except their own if he and Barry can create enough energy from their race to power the device. When Barry refuses to back out, the team locks him in a containment cell for his own protection. The team develops their own successful plan to send Zoom back to Earth-2, but Joe is pulled in with him. On Earth-2, Zoom reveals to Joe that the man in the iron mask is the real Jay Garrick. Wally releases Barry to rescue Joe. Barry agrees to race Zoom if he returns Joe unharmed. As Barry and Zoom race, the magnatar begins to charge. However, Barry creates a time remnant of himself, who gives his life to stop the magnatar, while Barry takes out Zoom. Defeated, Zoom is then taken away by the Time Wraiths for breaking the laws of time travel. The true Jay Garrick is revealed to be Henry's doppelganger, which distresses Barry. Wells and Jesse return with Jay to Earth-2. Still feeling broken and defeated, Barry travels back in time and stops the Reverse-Flash from killing his mother.

After preventing the murder of Nora Allen, Barry returns with Eobard Thawne to the present and imprisons him in a cage that dampens his speed. In the new timeline, which Thawne dubs "Flashpoint", both of Barry's parents are alive; Joe has a poor relationship with Wally and Iris and is chronically in trouble at work; Cisco is a billionaire tech magnate; and Caitlin is a pediatric ophthalmologist. There is also a new Flash in Central City called Kid Flash struggling with his own nemesis, Edward Clariss, known as "The Rival". Barry begins losing his memories of the original timeline due to the new timeline becoming permanent. After discovering Kid Flash is Wally, Barry teams up with him and stops Clariss, but Wally is critically injured in the process. Realizing that the new timeline is worse for those closest to him, Barry is forced to let Thawne return to the past and kill Nora, resetting the timeline and restoring Barry's memories. Back in the present, Barry learns that the timeline did not reset exactly. Meanwhile, Clariss is confronted by a mysterious voice and finds the message "Alchemy" being scratched into his mirror by an invisible force.

Barry learns of multiple changes to the timeline: Iris has not forgiven Joe for concealing that her mother was alive, Cisco is angry with him for not altering the timeline to save his brother Dante from being killed, and he has a new CSI partner, Julian Albert, who does not like or trust him. Barry decides to travel back to fix the damage, but he is intercepted by Jay Garrick. Jay tells Barry that the timeline never resets exactly and he has to learn to live with his mistakes. Meanwhile, Clariss has visions of "Flashpoint" and locates the person responsible, Alchemy, who restores Clariss' powers and full "Flashpoint" memories. Barry tells the team about the timeline's alterations before confronting Clariss at an abandoned warehouse. Alchemy is there as well, saying that he is "preparing this world" for a future event. Cisco arrives and helps Barry defeat Clariss, who is then incarcerated in Iron Heights. The team determines Alchemy is creating other metahumans from "Flashpoint" whom they need to track down. Cisco and Barry reconcile, as do Iris and Joe. Caitlin is secretly revealed to have gained cryokinetic powers. Barry and Iris begin dating, while Clariss is attacked in his cell.

Wells and Jesse return to Earth-1, where she reveals she has gained super speed from the second dark matter blast. Wells hopes everyone will dissuade her from using her powers. Elsewhere, foster child Frankie Kane develops metahuman magnetic powers that manifest as an alternate personality, Magenta, who attacks her abusive foster father. Julian confronts Frankie at the station and is nearly killed by Magenta. Barry learns from Magenta that she got her powers from Alchemy. She escapes and later goes to the Central City Hospital to kill her foster father by dropping an oil tanker on the building. Barry creates a vortex to hold the tanker in place, but is unable to confront Magenta simultaneously. Wells sends Jesse to help. She takes over the vortex while Barry talks Kane into gaining control over Magenta. Wally, grappling with disappointment over having no speed, realizes he is also having dreams from "Flashpoint". Wells tells Jesse that he will support her decision and presents her with her own speedster costume. Joe later shows Barry and Julian a video of Clariss being killed in his cell by an unseen force, manifesting only a flying ball of white light.

Three years ago, Sam Scudder and Rosalind Dillon, former cohorts of Leonard Snart, were caught in the original particle accelerator explosion. In the present, Barry begins training Jesse on how to use her powers. Wells suggests the team locate a doppleganger of his from another Earth to replace him on the team once he and Jesse leave. Scudder returns from being trapped in a mirror-like dimension with the ability to transport himself and others through reflective surfaces. He reunites with Dillon, who now has vertigo-inducing powers, and they go on a crime spree. Barry and Jesse (as "Jesse Quick") confront them but are defeated, and Barry ends up trapped inside a mirror by Scudder. Caitlin secretly uses her emerging ice powers to help Barry free himself from his predicament. He and Jesse then successfully capture Scudder and Dillon. After evaluating the candidates, the team recruits the friendly and eccentric Wells of Earth-19, despite the Earth-2 Wells' misgivings. Jesse and her father then return to Earth-2, with Wells apprising Cisco about Barry's suspicious escape. That night, Caitlin accidentally freezes the water in her shower and her appearance begins showing signs of her Earth-2 doppelganger, Killer Frost.

Without informing the others, Caitlin visits her estranged mother, Carla, at her medical research company to have her powers examined, but leaves after viciously attacking another scientist who intended to exploit her condition. Meanwhile, a gigantic creature repeatedly appears and disappears on the streets of Central City. Cisco grows suspicious of the newly-recruited "H.R." Wells when he does not provide much help in battling the monster. The monster is revealed to be simply a hologram operated by a bullied 15-year-old boy wanting to create fear in others. Barry exposes the deception in time to keep police snipers from harming civilians, and prevent Julian from shooting the boy, whom he mistakes for a metahuman. H.R. is revealed to have no technical knowledge at all. He admits that he is only an "idea man" for his tech company on Earth-19, and that he came to Earth-1 primarily to get material for a novel. The team decides to give him a chance to prove his worth as an assistant. A badly shaken Julian reconciles his differences with Barry. Carla informs Caitlin that her powers are increasing and that she needs to stop using them, or her condition will become irreversible.

When Wally relates his recent dreams of being Kid Flash, Barry reveals what happened to him during "Flashpoint". A metahuman H.R. nicknames "Shade" appears and murders a stockbroker. Caitlin reveals her powers to Cisco and has him "vibe" her to know her future. Cisco sees himself fighting Killer Frost, causing Caitlin to contemplate leaving for good. Alchemy begins summoning Wally to him, so the team locks him in the particle cells for his own safety. Meanwhile, Barry and the others stop Shade's next attack and capture him using meta-dampening handcuffs. Cisco tells everyone the truth about Caitlin, and Barry privately confesses to her that her powers came from him creating "Flashpoint". Wally volunteers to lead the team to Alchemy to capture the villain and stop the memories, which are physically injuring him. Barry, Joe and a S.W.A.T. team locate Alchemy and his followers and surround them. Another speedster, which only Barry can see, suddenly attacks them. As Barry fights it, Alchemy entices Wally to pick up his fallen energy weapon, which encases Wally in a crystal cocoon. Calling itself "Savitar", the speedster overpowers Barry and prepares to stab him.

Savitar takes Flash for a beatdown across the city at incredible speeds, but is stopped by Cisco and Caitlin's powers. Unfortunately, the usage of Caitlin's powers causes her Killer Frost persona to take over her. She ruthlessly interrogates Julian and a couple of Alchemy's henchmen for the location of their leader, hoping that he can take away her powers. Barry and Cisco imprison her to stop her from causing anymore harm, but are nearly torn apart when Caitlin reveals that Barry's responsible for Dante's death. Wally breaks out his cocoon with speedster powers and leaves the lab in a confused state. Knowing Caitlin can help them track Wally down, Barry attempts to coerce Caitlin into killing him, causing her to return to her normal state. The team manages to find Wally and sedate him to get out of his dazed condition, with Wally embracing his new abilities the following day. Barry is forced by Julian into retiring from the CCPD to protect Caitlin's secret from the police. Julian is revealed to be Doctor Alchemy and working for Savitar.

Barry investigates a meteor crash outside Central City that turns out to be a spaceship from which aliens emerge. Lyla tells the team that the "Dominators" landed previously in the 1950s, but then mysteriously departed. Needing help, Barry assembles the original Team Arrow, Thea, the Legends, and Supergirl of Earth-38. The team begins training at a S.T.A.R. Labs facility, sparring against Supergirl to prepare against the aliens. Cisco finds and reveals a message to Rip Hunter from Barry's future self, which exposes Barry's manipulation of the timeline and how it affected other team members. Oliver, Supergirl, Felicity, Martin and Jefferson become the only ones who still trust Barry. The Dominators abduct the President. Supergirl leads most of the others in a rescue effort, but the Dominators kill the President and trap them with a mind control device. The controlled heroes return and attack S.T.A.R. Labs. While Oliver holds them off, Barry lures Supergirl to the device and manipulates her into destroying it, freeing everyone. The team decides to trust Barry again. Suddenly, Sara, Ray, Diggle, Thea, and Oliver are teleported away before Barry can intervene.

This episode begins a crossover that continues on Arrow season 5 episode 8 and concludes on Legends of Tomorrow season 2 episode 7.

Barry asks Jay Garrick for help against Savitar. The two heroes locate and defeat Alchemy and return his weapon to its box, causing Savitar to disappear before he can kill Jay. Discovering Julian to be Alchemy, Barry reveals his own identity to him to get further information. Julian relates how he located the philosopher's stone following a vision of his dead sister, and that he has been having blackouts ever since. Savitar manifests through Cisco using visions of Dante and fights Barry and Wally, but Caitlin manages to convince Cisco to close the box again. The team communicates with Savitar through Julian, who claims that Barry, in the future, will imprison him. He also says that one teammate will betray them, another will fall, and a third will suffer a fate worse than death. Trying to end Savitar's threat, Barry and Jay throw the box into the Speed Force, but in the process, Barry is thrown five months into the future and witnesses Savitar killing Iris. Jay advises Barry that the future is not fixed. Wally is given his own "Kid Flash" uniform, Julian gets Barry's job back for him, and Barry rents a new apartment for himself and Iris.

The woman, who is called the Gypsy, is a bounty hunter with vibe powers similar to Cisco's intending to take H.R. back to Earth-19 for trial and execution, as inter-dimensional travel is forbidden there. Cisco demands a trial by combat, which she accepts. Barry and H.R. try to ambush her, but are easily defeated. Julian finds a stratagem for Cisco, who uses it to defeat her. Rather than killing her, he allows her to return to Earth-19, but she makes it clear that H.R. can never return, since she will state that she killed him. Meanwhile, Iris, determined to make a legacy for herself, persuades Wally to help her bust an arms dealer. While he is out scouting, she confronts the dealer, seemingly unafraid of death. Wally saves her. Joe gets angry and suspicious due to her lack of fear. Barry informs Wally that he needs to surpass Barry as a speedster in order to save Iris from Savitar.

The woman, who is called the Gypsy, is a bounty hunter with vibe powers similar to Cisco's intending to take H.R. back to Earth-19 for trial and execution, as inter-dimensional travel is forbidden there. Cisco demands a trial by combat, which she accepts. Barry and H.R. try to ambush her, but are easily defeated. Julian finds a stratagem for Cisco, who uses it to defeat her. Rather than killing her, he allows her to return to Earth-19, but she makes it clear that H.R. can never return, since she will state that she killed him. Meanwhile, Iris, determined to make a legacy for herself, persuades Wally to help her bust an arms dealer. While he is out scouting, she confronts the dealer, seemingly unafraid of death. Wally saves her. Joe gets angry and suspicious due to her lack of fear. Barry informs Wally that he needs to surpass Barry as a speedster in order to save Iris from Savitar.

Barry and Wally continue their training in order to save Iris from Savitar. They race against each other, and Barry wins by phasing through a building. Julian finds a decayed corpse that was murdered just eight hours ago. He informs Joe that this is surely the work of a metahuman. The body is taken to S.T.A.R. Labs for investigation, where Caitlin and Julian observe it turning to ash. Iris confesses to Barry that she is afraid of her future. The meta responsible for the disintegrated corpse attacks Joe and is revealed to be targeting the police who arrested him in Flashpoint. The metahuman tries to disintegrate a bridge on the train Joe is on, forcing Barry to phase the train through the wreckage of the bridge. Barry teaches Wally how to phase, which Wally uses to expose the meta to his blood and strip him of his powers. Joe insists that everyone be honest with him from now on after learning of Iris's future death. While practicing phasing, Wally is shocked to see Jesse coming through a portal. Jesse says her father has been abducted by Grodd and taken to Gorilla City.

Earth-2 Wells is captured while running through the woods. Jesse explains that he was leading an expedition to Gorilla City that was ambushed and killed while Wells disappeared. Barry recalls that in the future Central City will be attacked by gorillas. He, Julian, Cisco, and Caitlin go to rescue him but are captured by Grodd. Speaking through Wells, Grodd asks Barry to help him usurp his master Solovar. Barry agrees to fight Solovar in the arena for the lives of the others and wins, but refuses to kill him. Grodd seizes control of Gorilla City and prepares an invasion of Earth-1. The team asks Caitlin to kill Cisco so Grodd can't open a portal, but she refuses. Barry fakes his death and Grodd removes him from his cage. He resuscitates himself and frees the others, and they return to Earth-1. Jesse and her father reunite and Wally and Jesse recommit to their relationship. Julian asks Caitlin out on a date. Grodd assembles his army with a brainwashed Gypsy at his side.

Harry and H.R. clash over their different personalities. Jesse informs her father that she intends to stay on Earth-1 with Wally, which Harry initially tries to prevent. Harry subdues Gypsy when she ambushes Cisco and Barry, and the team realizes that Grodd and his forces have reached Central City. Using his powers, Cisco determines that the gorillas will attack the center of town. This turns out to be a distraction for Grodd to abduct a visiting Army general. Barry contemplates killing Grodd as the only way to permanently stop him and also change the future, but Harry encourages him to find another way. Taking control of the general, Grodd attempts a nuclear missile strike on the city. Barry prevents the attack, so Grodd and his gorilla army invade the city themselves. Cisco travels to Earth-19 to ask Gypsy for help. The speedsters distract the soldiers while Cisco and Gypsy bring Solovar to Earth-1, who defeats Grodd and assumes leadership once again. All the gorillas return to Earth-2, with the exception of Grodd, who is turned over to A.R.G.U.S. Cisco receives a kiss from Gypsy, and Barry proposes to Iris. While going out to pick up dinner for Jesse, Wally is confronted by Savitar.

Wally continues having visions of Savitar and, after a physical altercation with him, finally admits this to the team. The team attempts to question Savitar via Julian, who again acts as a conduit. Savitar casts doubt on whether the Philosopher's Stone is truly lost to the Speed Force. Caitlin confesses that she kept part of the Philosopher's Stone, hoping to use it to remove her powers. Barry and the team figure out that Savitar is trapped inside the Speed Force but Wally is at home with Jesse when they realize this. Wally, after being confronted by Savitar who appears as a vision of his mother, steals the stone fragment from the lab, creates a portal, and launches the fragment into the Speed Force, believing this will exile Savitar for good. Barry arrives just as the portal draws Wally into it, trapping him in the Speed Force. Savitar, having successfully manipulated Wally, emerges from the Speed Force and fights Barry, taunting him by boasting he will not kill him before Barry watches Iris die before his eyes. Barry is able to wound Savitar by using his vibrating hand to slice off his arm blade, but Savitar manages to retreat.

Feeling responsible for everything bad happening and that Wally is suffering inside the Speed Force, Barry decides to rescue him. Cisco vibes Barry into the Speed Force, where he encounters manifestations of friends and foes who had previously sacrificed their lives. Less accommodating than before, they push Barry to understand true sacrifice and that he must be the one to save Iris in the future. Barry is also confronted by his former enemy, Hunter Zolomon, and defeats him. Jay Garrick, having been contacted by Cisco, joins Barry inside the Speed Force and voluntarily takes Wally's place so Barry and Wally can escape. Meanwhile, Jesse uses the armor shard to locate and face Savitar by herself, managing to wound the villain before he escapes. Later, Jesse decides to go to Earth-3 to protect it until the team can free Jay from the Speed Force. Barry admits to Iris that even though he does love her but proposed for the wrong reasons and suggests they take some time apart from one another.

J'onn J'onzz and Mon-El arrive on Earth-1 with a comatose Kara. Music Meister attacks and places Barry in a similar coma. He wakes up in a musical world and finds Kara. Meister tells them that if they follow the script, they will return to the real world. Barry and Kara are forced to work as singers in a nightclub run by Malcolm, with Winn working as a piano player, Cisco as a waiter and Stein and Joe as two gangsters opposing Malcolm. Barry and Kara find Malcolm's son, Mon-El, and Stein's and Joe's daughter, Iris, in a forbidden relationship. Kara and Barry convince the pair to reveal their love, also helping Barry and Kara to realize their own mistakes. Malcolm, Stein and Joe subsequently decide to go to war. Barry and Kara are shot in the crossfire, but the real Cisco, Mon-El and Iris vibe into their world to save them, allowing Barry and Kara to admit their loves for Iris and Mon-El. They wake up in S.T.A.R. Labs; and Meister reveals that he just wanted them to realize their love. Kara's team returns to Earth-38; and Barry and Iris move back in together. He reproposes to Iris, who accepts.

Abra Kadabra, a criminal from the 64th century, comes to Central City, stealing from numerous tech companies and killing two guards. Gypsy returns, in pursuit of Kadabra, to avenge her partner. Kadabra offers the team the identity of Savitar in exchange for his freedom. Against Gypsy's wishes, a desperate Joe releases Kadabra, who escapes to Thawne's time vault after Gypsy fails to stop him, and retrieves a power source. Kadabra also triggers an explosion that critically injures Caitlin. Refusing to take off the necklace suppressing her powers, even though doing so could save her life, Caitlin asks Julian to perform surgery with her guidance instead. Kadabra attempts to return to his own time, having used the stolen technology to build his own time machine, but he is foiled by the team with Gypsy's help. Barry decides that the only way to save Iris' life is by traveling to the future. Later, a still-recovering Caitlin loses consciousness and begins convulsing, before her vital signs flatline. A distraught Julian rips the necklace from her neck and her vital signs return to normal, as her injuries heal rapidly. She awakens, but in the guise of Killer Frost, before vanishing in a cloud of ice.

Killer Frost destroys the necklace and escapes. Barry travels to 2024, when he learns that Cisco lost his powers after Killer Frost, who allied with Savitar, shattered Cisco's hands and forced him to use mechanical prosthetics; H.R. became a successful novelist; Julian works at Iron Heights tending to Killer Frost; Wally is catatonic with a shattered spine; Joe is depressed and bitter; future Barry is a recluse hiding in S.T.A.R. Labs; and in his absence, Scudder and Dillon have taken over Central City. Barry fails to learn Savitar's identity. Cisco secretly uses a device to prevent Barry from returning to the past, hoping he will put things right. Barry rounds up Julian, Joe and H.R. and reunites Team Flash. Scudder and Dillon overwhelm Barry with their powers, but after overhearing him, future Barry uses Cisco's device to negate the villains' abilities, helping Barry capture them. Future Barry gives Barry information about a Speed Force trap and tells him to find a physicist named Tracy Brand, who developed the trap four years after Iris's death. In the present, Killer Frost meets with Savitar, who offers her the chance to eliminate Caitlin forever. She is reluctant to trust him, but changes her mind when Savitar's armor opens up, and he steps out, revealing his identity to her.

Barry, Cisco and H.R. visit Tracy to seek help in making a trap for Savitar; they are interrupted by Killer Frost, who attempts to kill Tracy but is defeated before she escapes. Tracy goes to S.T.A.R Labs with Team Flash and is shown her future. Killer Frost later decides to kidnap Joe's girlfriend, Cecile, and demand Tracy in exchange. Killer Frost's plan fails, leading to a battle between her and Cisco. Defeated, she is whisked away by Savitar, but not before Cisco draws some of her blood in order to potentially make a cure for her powers. Later, Tracy, inspired by the events, plans to build a trap for Savitar, while Barry has a revelation regarding Savitar's identity and runs outside the city to confront him. Meanwhile, Joe admits his love to Cecile and tells her about Barry and Wally's alter egos. H.R. develops feelings for Tracy. Savitar corrects Barry's deduction and unmasks himself to be a future version of Barry.

Future Barry explains to his younger self that he is a time remnant, created by his future self while fighting Savitar. After being shunned by Team Flash, future Barry became depressed and ran back in time to ultimately become Savitar. He explains that he needs to kill Iris so that Barry will be forced to create him in the future. Cisco proposes they stop Savitar from remembering any of their strategies by stopping Barry from creating new memories, but miscalculations cause Barry to lose his memory. Savitar also loses all of his memories, resulting in Wally's powers disappearing, since Savitar never gave them to him. A pyromaniac named Lucious Coolidge gets released because of Barry's inability to testify correctly. Killer Frost helps Cisco and Julian develop a way for Barry to regain his memories so that Savitar can, as well. When Coolidge starts a fire, Iris helps Barry regain his memories in time to stop the fire with assistance from Wally. Tracy and H.R. develop a romance. She then shows the team the completed speed force trap, which requires a high amount of energy. The final scene cuts to a room that has an alien power source, as well as King Shark.

With 24 hours left before Iris dies, Team Flash learns that there is only one energy source that can power the "Speed Force Bazooka" in the form of a salvaged Dominator technology held at an A.R.G.U.S. facility. Barry and Cisco ask Lyla for it, but she refuses because of her mistrust of Barry due to his creation of Flashpoint. Barry then visits Snart in 1892, when he was travelling with the Legends, and recruits him to help Barry break into A.R.G.U.S. and steal the device. In the process, A.R.G.U.S. agents eventually capture Barry and Snart, but Lyla, seeing the kindness in Barry's actions, allows Barry to take the device. Snart advises Barry to use the goodness in him to defeat Savitar. Tracy decides to join the team. Cisco vibes about his battle with Killer Frost and leaves to fight her. Joe tries to hide Iris from Savitar on Earth-2 with Harry but future Barry tricks H.R. into revealing up her location by pretending to be his younger self, breaks Wally's leg and kidnaps Iris in front of a horrified Joe. Flash uses the "Speed Force Bazooka" on Savitar, but it fails when Savitar counteracts it with the Philosopher's Stone, which is made out of calcified speed force energy. Savitar then stabs Iris in the back in front of Flash seemingly killing her as he escapes.

H.R. reveals he swapped places with Iris and dies from his injuries. Realizing Iris is not dead, Savitar kidnaps Cisco and forces him to modify the Bazooka into an "inter-dimensional quantum splicer". This will allow Savitar to disperse himself throughout time and protect him from the paradox that threatens to erase him. Barry meets with Savitar, believing he can be redeemed and they go to S.T.A.R. Labs. Although Barry and Iris try to get through to him, Savitar wrecks the lab and orders Caitlin to kill Cisco, but Gypsy saves him. Savitar and Killer Frost open a portal into the Speed Force. The Black Flash intervenes, but is frozen by Caitlin. Savitar then attempts to execute his plan. However, Cisco modified the Bazooka into a 'skeleton key' which frees Jay from the Speed Force prison. Barry, Wally and Jay engage Savitar, while Cisco, with Gyspy's help, convinces Caitlin to abandon Savitar. Barry phases through and destroys Savitar's armor before Savitar is erased from existence. As Team Flash mourns H.R., Caitlin decides not to use Julian's cure, leaving the team so she may find her own purpose. Later on, an energy storm appears over Central City, caused by the Speed Force prison being empty. Barry explains that he needs to atone for creating Flashpoint and enters the prison, entrusting Central City to Iris and the team.

Iris has been aiding Team Flash in Central City for six months, but refuses to grieve Barry. A flying samurai with superpowers appears in Central City, threatening to destroy the city if the real Flash does not face him. Cisco reveals he has formulated a way to bring back Barry without destabilizing the Speed Force and tracks down Caitlin for help. Against Iris' orders, Team Flash successfully returns Barry, who rambles random statements and continually writes symbols on the walls. Wally engages the samurai, but is defeated. Cisco deciphers Barry's writings and finds an apparently meaningless sentence. In an attempt to recover Barry's memories, Iris gives herself up to the samurai. The plan works and Barry speeds away, rescuing Iris and defeating the samurai, who is revealed to be an android. Caitlin rejoins Team Flash, but is revealed to have been working for a mobster called Amunet, while also continuing to prevent the Killer Frost personality from emerging. The "Samuroid" is revealed to have been controlled by the Thinker, whose plan was to draw out the Flash for his next schemes.

When Barry, Joe, and Cisco report to a crime scene, they discover remnants of a mysterious code. Cisco presents Barry with a technologically advanced suit, intended to facilitate his activities. He tests it out, trying to save someone from a haywire car, caused by metahuman Ramsey Deacon. Gypsy arrives on Earth-1 for a date with Cisco, who is forced to cancel it so as to focus on Deacon. Acting on a suggestion from Caitlin, Iris signs her and Barry up for couples therapy to sort out their relationship. Deacon kidnaps a witness, who was previously a member of a tech team who sold him out of his idea. Barry and Wally go to save him, but Deacon uses his abilities to send Barry's suit haywire. On Iris's instructions, Barry throws lightning at himself, shorting out his suit. He then incapacitates Deacon, who is locked up in the meta wing of Iron Heights, revealed to be part of the Thinker's plan. Cisco finally goes out with Gypsy. Wondering how Deacon gained his powers being absent during the particle accelerator incident, Barry and Joe learn from Deacon that there are "others".

In flashbacks, the Thinker observes Becky Sharpe, a woman with seemingly unending bad luck, and determines that she will be easily manipulated. In the present, Becky robs a bank, and gets away when Barry slips on marbles. Harry arrives from Earth-2, and tells Wally that Jesse has decided to break up in order to focus on her vigilantism. Cisco deduces that Becky is a metahuman with the power of favorable luck while inducing misfortune to others. Barry realizes that the portal he used to escape the Speed Force exposed an entire busload of people, including Becky and Deacon, to transformative dark matter. Harry informs Cisco that Jesse has expelled him from her crime-fighting team due to his attitude. Becky's powers expand out of control, reactivating the particle accelerator, which Harry deliberately allows, nullifying Becky's powers and leading to her incarceration. Cisco and Harry identify twelve new metahumans created on the bus, and the latter suspects that an unknown party has manipulated events surrounding Barry's return. Wally decides to leave on a journey to find himself. The Thinker is revealed to be spying on S.T.A.R. Labs through the "Samuroid" helmet. Joe learns Cecile is pregnant.

Gypsy's father, Breacher, attacks Cisco, vowing to hunt and kill him in 24 hours, allowing the romance should he survive. Team Flash learns that the bus driver was murdered and tracks down another passenger, Ralph Dibny, former corrupt CCPD detective exposed by Barry and currently an infamous private investigator. As two thugs attack Dibny, he is revealed to have the power to stretch. Caitlin stabilizes his powers with a serum. The team learns that Ralph has been blackmailing Mayor Bellows for adultery, with the latter revealed to have hired the thugs. Barry confronts Ralph for his actions while the latter scolds him, claiming to have been a "good cop". He later stops blackmailing Bellows, who still attempts to kill him while Breacher mistakes the former for a Plastoid, the species that invaded Earth-19 previously, and attacks him. Cisco intervenes and saves Ralph, whom Barry, having revealed his alter-ego, convinces to help arrest an escaping Bellows. Admiring Cisco's gallantry, Breacher allows the relationship. Barry recruits Ralph for Team Flash and learns that someone named DeVoe instructed Ralph to watch Bellows. Barry remembers that Abra Kadabra and Savitar both mentioned DeVoe. Meanwhile, Caitlin finds a message on her apartment door.

While failing to track DeVoe, Team Flash is visited by Felicity, who joins Iris's bachelorette party. Mocking Cisco's plans for Barry's bachelor party, Ralph takes the men to a strip club, where they learn that Cecile's daughter, Joanie, is working. Joe confronts her, who states she is only doing feminist research. Ralph incites a brawl, leading to the men's arrest until Harry posts bail. Meanwhile, Amunet's enforcer, Norvock, demands Caitlin's return and attacks the women when she refuses. Killer Frost emerges and repels him, later telling Iris that Caitlin accepted Amunet's employment in exchange for the means to control Frost. Learning that Amunet is holding a metahuman she calls "the Weeper", whose tears are a strong narcotic, prisoner and intends to sell him, Iris's party decides to stop her. Though Caitlin refuses to join, she attacks Amunet when seeing her friends in danger. Using a strong magnet, the team robs Amunet's metal shards, leaving her powerless. Iris dissuades Frost from killing Amunet, who promises revenge. Both parties refuse to tell each other about their adventures. Iris asks Caitlin to be her maid of honor while Joe convinces Joanie to tell Cecile about her research. DeVoe captures the Weeper.

Barry trains Ralph to use his abilities, with Cisco making a stretchable suit for him. Another bus metahuman, a Lakota Sioux Native named Mina Chayton, who can animate statues, starts attacking Central City & stealing pieces of a Black Bison necklace, which she claims belongs to her tribe. When Barry and Ralph catch up to her, she attacks Barry with a caveman statue and attempts a getaway. Ralph chooses to stop her, but a little girl is injured in the process. Ralph regrets his actions, but is comforted by Barry. Chayton escapes CCPD, going after the last necklace piece held at the museum. When Barry and Ralph confront her, she brings a dinosaur skeleton to life. Barry arrests Chayton while Ralph saves a security guard from the skeleton. Later, Ralph reveals he mailed the necklace back to Chayton's tribe, before visiting the little girl in the hospital, using his abilities to entertain her. Meanwhile, Harry, trying to make friends, works with his doppelgangers of alternate Earths, The Council of Wells. They figure out that DeVoe is a man named Clifford DeVoe. Barry and Joe head to DeVoe's house, to find out that he is a middle-aged man in a wheelchair.

Barry and Joe interrogate DeVoe and his wife to try and get more information. In flashbacks, DeVoe and his wife build a thinking cap to improve his brain capacity, powering it through the particle accelerator explosion. DeVoe's increased brain power accelerates his amyotrophic lateral sclerosis, forcing his wife to build him a special chair to keep him alive. Barry discovers the camera in the Samuroid head and confronts DeVoe, who reveals his true identity, leading to Cisco dubbing him "The Thinker". Wally returns to Team Flash from Blue Valley.

Barry, Oliver, Sara, Alex, Martin and Jax wake up in a Nazi concentration camp on Earth-X wearing power dampeners. The arriving SS Sturmbannfuhrer is revealed to be the Earth-X doppelganger of Quentin Lance, who plans to execute them, but they are saved by Citizen Cold (the Earth-X doppelganger of Leonard Snart) and Ray Terrill. Snart and Terrill take them to the headquarters of the Freedom Fighters, where the team meets the resistance movement's leader, General Schott (Winn Schott's Earth-X doppelganger). They learn that the only way back to Earth-1 is through a temporal gateway in a research facility, which Schott plans to blow up to strand Dark Arrow (Oliver's Earth-X doppelganger) on Earth-1. Oliver disguises himself as Dark Arrow to infiltrate the facility and discovers the Nazi doomsday device against parallel Earths is a militarized timeship called Wellenreiter. Barry and Ray battle the Freedom Fighters' Red Tornado to stop it from destroying the gateway while the rest of the team enters the facility to reactivate its portal, during which Stein is shot and gravely wounded. On Earth-1, Thawne prepares to perform surgery on Kara to save Overgirl. Felicity and Iris try to stop him, but are captured.


This episode continues a crossover event that begins on Supergirl season 3 episode 8 and Arrow season 6 episode 8, and concludes on Legends of Tomorrow season 3 episode 8.

While out Christmas shopping, Barry is ambushed and kidnapped by DeVoe while Caitlin is kidnapped from Jitters by Amunet. Iris claims they have to look for both of them, despite Wells' claim that they have insufficient time and resources and that they can only afford to search for one. Barry is held in DeVoe's lair. Caitlin is forced by Amunet to perform surgery on a metahuman named Dominic Lanse, who can read minds. They try to escape, but Amunet blocks their exit. Caitlin manages to briefly incapacitate Amunet, and she and Dominic flee the building they are being held in. Once outside, they are rescued by Cisco and Ralph, as Iris has chosen to focus on finding Caitlin. Barry manages to escape from DeVoe. Team Flash celebrates Christmas at the West house and Dominic joins them. Barry gets a security alert from his apartment. When he arrives, he receives a phone call from Dominic, who reveals that Amunet re-kidnapped Dominic and DeVoe has transferred his consciousness into Dominic's body. Barry discovers DeVoe's original body dead on his apartment floor and he realizes DeVoe has framed him for his "murder"; the police arrive, and Barry lets himself get arrested, not wanting to leave Iris again.

Barry stands trial for the murder of Clifford DeVoe, with Cecile representing him. Cisco and Joe have to leave during the trial for a meta investigation, in which a meta caused people to collapse. Singh reveals to Joe he is appearing as a witness for the prosecution against Barry. The meta is eventually discovered as Neil Borman, who is a meta who produces radiation, which is causing the illness and collapsing. Barry takes him on, but is ill equipped to deal with the situation. Cisco and Killer Frost travel to the scene where Caitlin tries to freeze Borman, who quickly defrosts and incapacitates Caitlin. Barry creates a vacuum seal around Borman to contain the radiation, with Cisco transporting the radiation to the dead Earth-15, draining the meta and defeating him. Barry is eventually found guilty by the jury and is sentenced to life in prison.

Barry uses his speed to secretly help the guards contain the other inmates during a prison riot. He also befriends Dave Ratchet, his father's former cellmate. The next day, Barry meets Axel Walker who was later broken out of prison by his mother Zoey Clark, his father's one-time partner Prank. Axel challenges Ralph by threatening to cause chaos in the city. Ralph attempts to stop him but is wounded by Axel and is evacuated by Cisco. Ralph sneaks into the prison to talk to Barry about how scared he is. Barry reassures him that being a hero isn't about not being scared, but about having the ability to rise above your fear. Cisco and Caitlin go to rescue the hostages, but get captured by Axel and Zoey, who intend to kill them. Ralph arrives, and attempts to shield the two from an acid shower, until Wells manages to hack into the shower system to neutralize its acidity. Iris visits Barry in prison, where they reaffirm their love for each other. Ralph and Cisco go to get coffee, where they meet the excitable girl from the wedding. The girl writes in her journal, where she appears to be writing in the language Barry was using when he came out of the Speed Force.

Cecile develops telepathic abilities as a result of her pregnancy, combined with dormant dark matter in her cells, which Caitlin assures her should be temporary. In prison, Barry learns that Ratchet is innocent of a robbery-homicide that was actually committed by Sylbert Rundine fifteen years prior. Barry asks the team to look into the case. Rundine turns out to be a bus meta with the ability to shrink and enlarge objects, and he shrinks Cisco and Ralph while escaping. Harry's attempted cure backfires, and Caitlin determines that if they are not re-enlarged within a certain period of time, their bodies will explode. The team confronts Rundine at a warehouse, where Harry tricks him into re-enlarging Ralph and Cisco. Rundine is arrested, but refuses to confess to the earlier crime. Barry gathers that even if Ratchet went free, he would be as unhappy in the city as he is in prison; he wishes to live in a secluded Chinese village called Jiaju, but fears he will never get there. Barry then uses his speed to take Ratchet to Jiaju, where he can live out his dream. After discovering Barry is the Flash, the prison's warden, Gregory Wolfe, locks Barry in his private metahuman wing, intending to sell him to Amunet.

Wolfe plans to sell Barry and the imprisoned bus metas (Ramsey Deacon, Becky Sharpe, Mina Chaytan, and Sylbert Rundine) to Amunet, so they plan to escape. Cecile discovers Wolfe's plans after reading his mind. Ralph encounters a former colleague and his negative interaction with him prompts the discovery that he can shapeshift. His lack of mastery of the new ability prevents his attempt to foil Amunet's deal with Wolfe. Barry helps the metas escape the power dampeners, but they are cornered by Wolfe and Amunet. DeVoe arrives and again uses his chair to extract the metas' abilities, before transferring his mind into Sharpe's body. He then kills Wolfe as Marlize looks on in horror; Amunet flees. Ralph uses his shapeshifting ability to appear as the original DeVoe at Barry's appeal, claiming that he was unconscious at Barry's loft but not dead, which clears Barry's name. Team Flash realizes that DeVoe is only stealing powers from metahumans who were on the bus when the dark matter wave was unleashed, which means he will likely target Ralph as well. Back at the DeVoes' house, their marriage continues to deteriorate, and DeVoe drugs his wife with the Weeper's tears to maintain her devotion towards him.

Barry is put on indefinite leave at the CCPD due to his connection with the DeVoe case. The team encounter another bus metahuman named Izzy Bowin with sound wave abilities, amplified by her violin. She manages to use her abilities when DeVoe (inside Sharpe's body) comes to claim her. Barry and Ralph help to train Izzy to refine her abilities, which proves difficult when she gets hurt. Eventually DeVoe shows up once again, using Dominic's and Becky's abilities to make Barry experience a brain aneurysm, while using Rundine's abilities to incapacitate Ralph. DeVoe then once again uses the chair to transfer his mind into Izzy's body and escapes. Both Ralph and Barry comfort each other over their respective losses: Barry being let go from the police force and Ralph losing Izzy to DeVoe. These losses enforce both Barry's and Ralph's determination to bring DeVoe down and save the three remaining metas.

Jesse comes to Earth-1 to have a talk with her dad. Eco-terrorist Veronica Dale sets off a nuclear bomb, which Barry tries to stop, entering a form of superspeed known as Flashtime, where everything is frozen. However, the bomb has already detonated, and he and Jesse cannot stop it or save everyone with superspeed. Jay Garrick comes from Earth-3 to help, but they are still unable to stop it. Barry remains in Flashtime for hours, bringing each of his friends into it, in an attempt to find a solution; they discuss options such as freezing it or sending it to another Earth, but none of those solutions prove to be viable. Eventually, Iris gives him the idea to retrieve the Quark Sphere from the Speed Force to send a blast lightning through the bomb, enough to disable it. Barry does so, and throws the Sphere back into the Speed Force, saving Central City. Jay admits he is retiring and going to train a new "female" speedster. Jesse and Jay return to their Earths, and Caitlin and Wells go for a coffee, where they encounter the mysterious girl.

A metahuman with fire powers tries to rob Central City bank. Another bus meta named Matthew Kim touches the metahuman, which causes his powers to transfer to another individual. When Joe, Iris and Barry turn up to ask Kim a few questions, Barry and Iris come into contact with Kim, causing Barry to lose his speed and Iris to gain superspeed. Inspired by Thawne, Harry plans to build his own thinking cap to outwit DeVoe. With their roles reversed, Iris becomes Central City's hero speedster, while Barry must learn to act as team leader. The new metahuman demands money and terrorizes the city with his fire powers. Using Wells' thinking cap, the Team comes up with the idea for Iris to create a tidal wave, negating the flames and defeating the meta. Back at S.T.A.R. Labs, Kim touches Iris and Barry again, restoring the Flash's speed. At home, Iris admits that while she did enjoy having superspeed, Central City needs the light that Barry was, and she is happy being team leader. Wells uses his thinking cap once more, determining the final two bus metas are Janet Petty and Edwin Gauss.

Barry and Ralph train to defeat DeVoe, with Barry becoming annoyed at Ralph's apparent inability to be serious. The team manages to locate another bus meta, Janet Petty. When Barry and Ralph confront her, it is revealed that Petty can manipulate a person's gravitational pull, which she demonstrates on Barry. Fearing once again that Ralph is not taking things seriously, Barry refuses to work with him. Ralph reveals his comedic attitude is due to a difficult childhood where his father abandoned him, causing him to make jokes whenever he is scared or under pressure. Barry relents and they go to stop Janet at a gala event. Janet uses her powers on Barry, causing him to float into the atmosphere. Barry tells the team to trust Ralph to improvise. Ralph detains Janet, then becomes a giant airbag to allow Barry to land safely. DeVoe's wife discovers he has been drugging her, so she will continue to assist him. Breacher comes to Earth-1 to ask Cisco for help as some of his powers have failed. Harry takes the thinking cap to Thawne's time vault to recharge it and activates Gideon.

Team Flash track down the final bus meta Edwin Gauss, but are followed by the Samuroid, who injures Caitlin. The team rush back to Star Labs to regroup and heal. Caitlin reveals to Iris that Killer Frost is activated by her adrenal gland, and she is working on a way to separate them. Harry comes up with a tuning fork weapon that mimics Izzy's abilities in order to defeat DeVoe. Ralph reveals to Barry that he isn't afraid of losing his own life, but of Team Flash losing theirs, as he considers them family. Wells is shown to be addicted to the Thinking Cap, which Joe helps him deal with. Ralph takes the fork, with the intent to go with Edwin to kill DeVoe, which Barry argues against. Eventually, DeVoe manages to take over Edwin's mind, and as well takes the abilities of Janet Petty and Matthew Kim, before transferring his mind into Ralph's body. The team try to stop him, but DeVoe incapacitates them, and alters Caitlin's DNA, removing the dark matter and Killer Frost, before leaving. Back at his lair, DeVoe uses Ralph's morphing abilities to morph back into his original form, while he and Marlize plan their next move to destroy Team Flash.

With DeVoe moving forward with his plans, Team Flash decide to secure Neil Borman. Barry and Cisco travel to Earth-X to recruit Leo Snart as a backup, but are followed to Earth-1 by the Earth-X doppelganger of Laurel Lance. Team Flash plan to deliver Borman to a safe ARGUS facility, using a suit to contain the radiation, with Snart on hand, in case Borman goes nuclear. Snart agrees to help, but claims he can only stay for 24 hours, as he is due to get married to Ray Terrill. DeVoe attempts to intercept the transfer, but he and Team Flash are further ambushed by Earth-X Laurel, who kidnaps Caitlin, Borman and Joe, holding them at CCPD. Snart learns about Ralph, and convinces Barry to allow himself to grieve his fallen allies, which Barry eventually does, giving him strength to defeat Laurel. Lyla transfers Borman to another facility and Leo returns to Earth-X. Cisco and Wells come up with a plan to boost Wells' thinking cap. DeVoe goes more into his "god-complex"; stating that human emotion is a weakness, causing Marlize to doubt him.

DeVoe starts gathering the technology required to build the Enlightenment Machine, including murdering anyone who gets in his way. Barry, Cisco, Iris and Harry attempt to trigger Killer Frost's powers in Caitlin, but do not succeed. Harry reveals to the team that the amount of dark matter he used with the Thinking Cap caused brain damage. Cisco, Gypsy, Barry and Caitlin fight Marlize and DeVoe when they acquire the computers required to power the Enlightenment Machine. Flashbacks reveal partially why Marlize follows DeVoe: she was a humanitarian worker in Kenya who created a water purifier for a villager, but when warlords found out about it, they attacked and killed everyone. Marlize pleads with DeVoe when he begins choking Gypsy; she later decides to leave him, encasing his chair in a force-field so DeVoe cannot stop her from leaving the pocket dimension. The team realizes that DeVoe plans to use the Enlightenment Machine to launch dark matter towards Earth, reverting all of humanity into a simplified state, similar to what Harry is dealing with. The mysterious girl brings a gift to Cecile and Joe's baby shower and, after leaving quickly, runs away using speedster abilities.

After Harry is expelled from the Council of Wells due to his declining intelligence, Cisco assembles a Council of Harrisons to try and come up with a way of stopping Harry's intelligence loss. Team Flash reluctantly go to Amunet for help, encountering her successor Norvok in the process, though Barry insists Amunet must not kill. The team is eventually given a bomb made from Amunet's metal which will be capable of destroying one of DeVoe's satellites, and Harry manages to work out that DeVoe's plan might be changing because Marlize is no longer with him. Iris posts an article revealing DeVoe's plan and the residents of Central City begin reporting DeVoe sightings, which Iris believes will hamper his ability to remain undetected.

DeVoe infiltrates the A.R.G.U.S. facility holding Fallout by impersonating John Diggle and kills most of the security, except for a few hostages; overcharging and killing Fallout to be a nuclear battery for the satellites. Barry runs to Star City and brings back John to reveal the location of the facility. Caitlin and Cisco ask Barry to train them in Flashtime so that they can save the hostages and Barry can follow DeVoe through the breach before it closes. In the last stages of pregnancy, Cecile's telepathy causes her to take on the personality and thoughts of anyone nearby. Harry and Iris track Marlize to London, and use the last extrapolator to get there. Caitlin and Cisco are able to rescue the hostages. Searching her mind for Killer Frost, Catlin has Cisco vibe her into a repressed memory of a childhood accident; Killer Frost was already part of Caitlin decades before the particle accelerator had created any metas. Barry manages to follow DeVoe through the breach and destroys one of the satellites with Amunet's bomb. DeVoe takes control of S.T.A.R. Labs and uses its satellite to replace the one destroyed. He initiates the Enlightenment protocol in the time vault.

After the Enlightenment begins, Marlize joins Team Flash as Cecile goes into labor. Marlize uses Cecile's powers to send Barry into DeVoe's consciousness to find the good left in him. Barry finds Ralph alive in DeVoe's consciousness and together they find the "good" DeVoe dead. DeVoe attempts to keep them from reaching the nexus of his mind, as he follows Team Flash to a pocket dimension. In his consciousness, DeVoe multiplies himself to fight Barry and Ralph as he takes down Team Flash. Barry and Ralph make it to the nexus; Barry wakes up in the real world and Ralph reclaims his body just as DeVoe was going to kill Cecile. DeVoe reappears as a hologram through his chair until Marlize destroys it, killing him. Barry, Cisco and Ralph shield civilians from the falling satellites and the mysterious girl helps Barry destroy the last one. Harry's brain resets but is mostly restored by Marlize; he decides to return to Earth-2 to be with Jesse. Team Flash celebrates DeVoe's defeat with Wally (who returned from the Legends) and Cecile's newborn daughter Jenna. The mysterious girl arrives to reveal herself as Barry and Iris' daughter from the future, Nora; she claims to have made "a big, big mistake".

Team Flash meet Nora, Barry and Iris' daughter from the future. While Iris expresses excitement, Barry is concerned that she could alter the timeline based on his own mistakes with time travel. When Barry tries to send Nora home, Wally reveals that Nora's blood is saturated with negative tachyons, which prevents her from using the Speed Force or the Legends' Waverider to time travel. Barry asks Nora what happens to him in the future, so she reveals that he never returned after disappearing in 2024 and that she traveled back in time to meet him. A new metahuman named Gridlock, who is able to harness kinetic energy, causes a plane to fall, so Barry, Nora, Wally, and Cisco team up to save it, with Nora providing Barry a Flash ring suit. They phase the plane through the buildings so it lands safely in the river. While Gridlock is being transported to prison, the convoy is attacked by a masked individual, who tells Gridlock that he plans to wipe out all metahumans before approaching him with a lightning-shaped dagger.

Barry struggles to train the overeager Nora, who gets herself hired as a CSI intern to spend more time with her father, much to Iris' discomfort. Caitlin and Ralph try to help Cisco following his breakup with Gypsy, with Cisco eventually accepting he needs to move on. Caitlin refuses to pursue the idea that her father might still be alive, despite Ralph's insistence. Cecile starts to lose her telepathy and struggles to connect with her child without being able to know her thoughts. Meanwhile, a new meta called "Block", who can create blocks of dense air, steals weapons from her old gang, and while trying to stop her, the team has their first encounter with Cicada: the masked man who killed Gridlock. He stabs Block, but Nora manages to speed her away from the scene. Cicada then uses his dagger, which he has telekinetic control of, to neutralize the team's powers, beat them severely, slash Cisco's hands, and nearly kill Barry before Nora drives him off. Cisco vibes Caitlin, learning that her mother is involved with her father's disappearance. Iris reveals that she has been investigating the masked individual, and the team discovers that Nora already knows about him.

The team recruits Harrison Sherloque Wells to help them catch Cicada, who Nora reveals is unstoppable in the future. Caitlin and Ralph confront Caitlin's mother Carla Tannhauser, who denies forging her husband's death certificate. They later break into her files and find a suicide note from Caitlin's father. Sherloque pinpoints Cicada as David Hersch, as he was previously correct 37 times. As a result of Nora's tampering with the timeline however, his identity on Earth-1 is different. Cicada attacks Joe to lure out Vibe and when Cisco arrives, Cicada stabs him and breaks his arm. Barry arrives, but is easily defeated. Nora enacts an explosion to drive Cicada off, which results in Cisco's apparent death. However, Cisco reappears, having used a breach machine to escape. With the public and Cicada believing that Vibe is dead, Sherloque agrees to help the team. Caitlin deciphers a hidden message from her father, Thomas, asking her to come find him. Cicada visits his comatose niece in the hospital. Nora agrees to stay with her parents, despite her seemingly strained relationship with Iris. Sherloque begins to suspect that Nora is not in 2018 for the reasons she gave.

The team discover articles about XS, written by one of Iris' former colleagues, Spencer Young, which are all published just before the events take place. Iris contacts Spencer to ask her to refrain from putting XS in her articles in order to protect Nora, but fails. Spencer is revealed to be in possession of a phone that allows her to control people's minds so she can create articles for her blog. Iris learns from Nora that she does not like her because in the future, the former implanted her with a meta dampening chip that disabled her powers. Barry and Nora go to the stadium when a bomb threat is reported, where Spencer uses her tech to hypnotize XS into trying to kill the Flash. Iris eventually stops XS by shooting her with a tranquilizer dart, allowing Nora to regain her mind and Barry to arrest Spencer. The team discover that Spencer's phone and Cicada's dagger have meta abilities, created from DeVoe's satellite explosion, meaning meta-tech could be in the hands of anyone. It is later revealed that Cicada has acquired super-strength.

Barry and Nora go to stop some art thieves, with Iris getting frustrated when Nora cuts her off. Nora reveals that in the future, Iris is cold, distant, and critical of her actions. Nora goes to spend some time with Cecile, finding out more about Iris from her. Later, a new meta called Rag Doll attacks an architect and destroys his office, though the Flash saves him. Iris and Barry try to investigate the new meta, but the latter gets captured by Rag Doll and held hostage on a rooftop with power dampening cuffs (though the villain is unaware of Barry's abilities). Ralph and Iris go to save Barry, with Iris jumping off the building to remove Barry's cuffs while he is falling and allowing him to save them just as Ralph defeats Rag Doll. Iris later reconciles with Nora, and the two start to grow closer. Meanwhile, Cisco, Caitlin, Ralph, and Sherloque investigate Caitlin's father and track him to a university office and a chem lab before Cisco suddenly collapses. As his damaged hands negatively affect his health while using his powers, Cisco takes control of DeVoe's satellites so he can try and find both Thomas and Cicada.

Barry, Cisco and Caitlin find her father, Thomas, in an arctic facility and bring him to S.T.A.R. Labs, where he reveals that both he and Caitlin developed ice powers as a result of his experiments in trying to treat their ALS gene. Thomas claims he is dying as a result of never having manifested an alternate personality like Killer Frost, but Cisco is suspicious. He teleports back to Thomas' lab, where he discovers "Thomas" is actually an alternate personality wearing skin grafts to pose as him. Caitlin realizes that a serum she created to cure her father would actually kill his human side. Cornered, Thomas' alter ego, "Icicle", emerges and attempts to kill Team Flash with absolute zero temperatures, but Caitlin proves to be immune. With the rest of the team incapacitated, Killer Frost returns and defeats Icicle, forcing him to flee. Team Flash determines that Dominic Lanse / Brainstorm's powers caused Killer Frost's disappearance and they also learn the name of Cicada's niece, Grace.

Barry attempts to see Grace, but Dr. Ambres impedes him. Barry and Nora later stop a freak lightning storm from hitting Central City's power grid. Team Flash suspect Mark Mardon, even though he's in jail, but Nora and Barry instead encounter his estranged daughter, Joss Jackam / Weather Witch, who wields a weather control staff like her father. Barry and Nora bring Mardon to her in order to appease her, but to no avail. An angered Joss attacks an airport with a lightning tornado, so Barry uses Mardon's wand to absorb Joss' lightning and subdue her. Team Flash finally discovers Cicada's identity: Orlin Dwyer. In flashbacks, Orlin is shown adopting Grace after her mother's death in a metahuman attack and while bonding, debris from DeVoe's satellite put Grace in a coma and impaled Orlin with shrapnel that would later become his dagger. Blaming metahumans for what happened, Orlin vows to exterminate them all on Grace's behalf.

Barry and Nora time travel to gather items needed to stop Cicada; a highly magnetic alloy from Savitar's armor, Harry Wells' Speed Force transmitter, and dark matter. They first travel to Team Flash's final battle with Savitar. After a Time Wraith appears, Barry distracts it so Nora can retrieve a piece of the armor. They next travel to when Zoom stole Barry's speed for the transmitter, which Barry obtains from Harry. Zoom discovers Barry and Nora and gives chase before he is stopped by the Time Wraith; though this breaks the transmitter in the process. Even though he is reluctant, Nora convinces Barry to ask Eobard Thawne for help. Despite some initial difficulty, Barry convinces Thawne to fix the transmitter by claiming he will never get home if he does not. Finally, Barry and Nora travel to the night of the particle accelerator explosion. In the Time Vault, Gideon reroutes part of the dark matter through the shard and transmitter, and Barry reveals to Nora that Thawne killed his mother. Back in the present, Team Flash separates Cicada from his dagger temporarily before he escapes. Nora returns to 2049 to confront Thawne at Iron Heights.

On a decimated Earth-90, the Flash is seen crawling towards a book, but a mysterious stranger picks it up and uses it to destroy that reality; though the Flash escapes. On Earth-1, the stranger presents the book to Arkham Asylum psychiatrist Dr. John Deegan, and instructs him to rewrite reality as he sees fit. The following morning, under threatening red skies, Oliver Queen and Barry discover that they have swapped lives, with everyone believing they are each other. When they seek the assistance of Team Flash, they do not believe them and lock Barry and Oliver in the pipeline. Barry and Oliver use each other's abilities to escape and convince a reluctant Iris to allow them to flee to Earth-38 to enlist the help of Kara Danvers / Supergirl and her cousin, Clark Kent / Superman. Back on Earth-1, the heroes join forces to stop A.M.A.Z.O., an android that can copy their abilities. They stop the android and, after seeing a vision of the stranger from Cisco, they realize they must travel to Gotham City.

This episode begins a crossover event that continues on Arrow season 7 episode 9 and concludes on Supergirl season 4 episode 9.

Nora refuses to continue working with Thawne upon learning he killed her grandmother. Barry and Nora encounter a new villain, Silver Ghost, who possesses meta tech allowing her to access any car. An encounter with her and her tech leaves Barry phasing uncontrollably, so Nora and Team Flash help him into the pipeline, where he can stabilize for 24 hours. Silver Ghost frees Joss Jackam from CCPD's custody so she can help her steal a WayneTech car in A.R.G.U.S.'s possession. Silver Ghost uses the car's tech to evade capture, until Cisco patches Nora's voice into the radio, urging Joss for a second chance and to turn herself in. Joss secretly disables the car, before escaping with Silver Ghost. Caitlin helps heal Cisco's hands and they agree to try to develop a meta cure with the caveat that it is never forced on anyone. Nora returns to the future and reluctantly agrees to help Thawne, who has less than an hour left to live. Sherloque gains access to the Time Vault, but discovers the files on Nora West-Allen have been deleted by her.

Cicada returns, killing metahumans from an arrest log provided by someone inside CCPD. When Team Flash tries to stop him, the villain paralyzes Nora and slows down her speed healing. Once the team determines Cicada's pattern, Cecile tracks down the informant while the rest round up the remaining metas on the log. Caitlin continues working on the metahuman cure, but needs blood from a recently created one. Cicada finds the meta group protected by Team Flash. While Ralph helps the metas escape, Flash and Killer Frost distract Cicada; the latter drawing blood from him for the cure. Incensed from what happened to Nora, Flash nearly kills Cicada before she rushes over to stop him; inadvertently allowing the killer to escape. Sherloque ignores Iris' order to stop investigating Nora and discovers two handwriting styles in her journal. While having dinner with Iris and Nora, Barry comes up with the idea to appeal to Cicada's heart by trying to wake Grace up.

The team plan to wake Grace up using Sherloque's Memory Machine from Earth-221. Despite his instructions however, Nora enters Grace's memories by herself to prevent the others from learning about her secret alliance with Thawne. To her horror, she discovers that Grace is consciously aware of Orlin's actions and wholeheartedly supports him in his anti-metahuman agenda before she is attacked by a female version of Cicada. Meanwhile, Barry and Iris discover what Nora did and go in after her, only to end up in her memories of the Flash Museum and attacked by the Reverse-Flash exhibit. Despite heavy resistance, Barry and Iris manage to escape Nora's memories and save her from Cicada. But they are unable to bring Grace as she refuses to wake up and believes Nora is a liar. Upon further review of their adventure, Caitlin learns that a satellite shard became lodged in Grace's brain and created a barrier around it, meaning they cannot try again. Iris establishes the Central City Citizen, which Nora reveals was originally founded in 2021; meaning Iris is changing the future. Cisco makes some headway on the meta cure, which Barry decides to use on Cicada.

Team Flash completes the metahuman cure, but require Cicada to hold still long enough for it to take effect. Ralph finds a device capable of doing so in the hands of a metahuman crime boss called Goldface. Despite Barry's hesitation, he and Ralph go undercover as criminals to retrieve it from him. Though he is suspicious, Goldface decides to take the heroes on a job to steal a 3-D printer from Ivo Labs in exchange for the device. Even though they are discovered, Barry and Ralph are able to stop Goldface and his men. Elsewhere, Iris starts investigating Cicada for the Central City Citizen and discovers where he lives. She is able to get inside, but he sees through her and tries to kill her. After a protracted fight, she discovers his weakness; but when Team Flash investigate, they find Cicada gone. Under orders from Thawne, Nora tries to steer Sherloque away from her by helping him fall in love with a woman named Renee Adler. Despite a bad first meeting, Sherloque and Renee eventually fall for each other. After discovering she is a meta, Sherloque devotes all of his attention to protecting her from Cicada.

Barry takes the meta cure into the Speed Force for an hour to help speed up the synthesizing process, leaving an uneasy Nora behind. Elsewhere, Cicada kidnaps Iris, but she manages to alert Nora and Killer Frost to her location. They arrive, but Cicada slays Killer Frost, distressing Nora to the point where she runs so fast, she resets the timeline. When Nora tries to prevent Iris' death, Cicada ends up kidnapping Ralph instead, and although the situation plays out like last time, Ralph dies instead. Nora repeatedly resets the timeline, but on each new attempt, one of Caitlin, Cecile, Cisco, and Ralph always gets killed. Finally, Cisco reveals the loops to the team, forcing Nora to confess what has happened. Cisco consoles her, and together with the rest of the team, works on a new plan to stop Cicada. This time, they make it so that Cicada accidentally stabs himself with his dagger, forcing him to flee. Once Barry returns and learns what Nora has done, he warns her against altering time any further. Elsewhere, Sherloque manages to decode Nora's entire journal using symbols she unwittingly revealed during the meeting with the team.

The metahuman cure is finished and Team Flash decides that King Shark would be the ideal subject to test it on. The team travels to A.R.G.U.S. and ask Lyla to get in contact with King Shark, who aggressively attacks the team under the mind-control of Gorilla Grodd. Barry reacts by injecting the cure into King Shark, turning him back into his human form - Shay Lamden. Back at S.T.A.R. Labs, Caitlin discovers that although the cure worked, there is still dark matter in Shay's pituitary gland and his body rapidly changes back and forth between his two forms. Shay's wife, of Earth-1, Tanya, is convinced by Sherloque to talk with Shay. Later, Grodd mind-controls Cisco and Caitlin into stealing Dr. Lamden's telepathy-crown to amplify his powers so he can control all of Central City. Seeing no other option and wanting to make amends for his crimes as King Shark, Shay gives up his chance of being human to help Team Flash stop Grodd; even in spite of the possibility of never being human again. Meanwhile, Joe returns home to Cecile and trains Iris to overcome Cicada who Barry suggests they offer the cure to instead of forcing it on him.

In 2049, Thawne warns Nora that they have to act fast to stop Cicada once and for all because a new timeline is trying to push its way into being -- and bring something really big with it. In the present, Nora and Barry confront a new metahuman, Acid Master, whose burn mark was on a newspaper article shown to Nora in the future, which leads her to deduce that the final confrontation with Cicada is upon them. Meanwhile, Joe and Cecile interrogate Dr. Ambres about working with Dwyer. She then reveals to them that Dwyer's niece Grace is a metahuman now. Barry reveals this to Dwyer, which makes him reconsider his whole vendetta, and successfully convinces him to take the metahuman cure by bringing up the possibility of curing Grace. Dwyer is taken to S.T.A.R. Labs and given the cure, but during the operation the facility is attacked by a new Cicada, who gains control of Dwyer's dagger and uses it to kill Dr. Ambres, before abducting Dwyer. At a cabin in the woods, the new Cicada unmasks herself to reveal an adult Grace.

In 2049, Thawne is surprised by the appearance of a new Cicada and with no other options, asks Nora to reveal the relationship between them to her father. The adult Grace comes from a future where metahumans thrive to complete what she believes is still her uncle's mission. Team Flash discovers that the new Cicada arrived in a Time Sphere, stolen from S.T.A.R. Labs' storage in the future. Following some leads, including a police file stolen by the new Cicada, they correctly deduce her identity. Cicada targets Vickie Bolen, a metahuman who accidentally caused an explosion that killed her parents, but Team Flash intervenes. Orlin arrives and tries to talk his niece into abandoning her vendetta, which leads to her killing him. Meanwhile, Sherloque finds out that Thawne, when he was posing as Dr. Wells, cracked a source code for the multiverse. Identifying Thawne as the second person who wrote in Nora's journals, Sherloque exposes her partnership in front of the team, causing Barry to lock his daughter in the pipeline.

Team Flash read Nora's journal and learn that she discovered her powers and relation to the Flash after subsequent encounters with two speedsters: August Heart / Godspeed and Thawne. Flash-forwards show Nora working as a forensic scientist like her father. After being hit by Godspeed, Nora discovers she had a chip implanted into her that dampened her powers, which causes a rift between her and her mother. After Godspeed's citywide rampage kills Nora's best friend and co-worker Lia, Thawne helps Nora control her newfound powers and defeat the rampaging speedster; after which Thawne becomes her mentor as he did with Barry. With Thawne's help, Nora finds the Time Vault, where she learns that her father was the Flash. In the present, Iris releases Nora out of guilt after learning of her future self's deception, but Barry sends her back to her time out of distrust, stating that he would feel any future attempts made by her to time travel. Barry then visits Thawne at Iron Heights, glad that he is awaiting execution for his crimes.

Barry and Iris fight over him sending Nora back without consulting her. Iris reprograms the Time Sphere and travels to 2049, where Nora wants Thawne to teach her to use the Negative Speed Force to time travel without detection. After an unsuccessful attempt, Nora and Thawne are confronted by Iris. Instead of going with her, an angered Nora enters the Negative Speed Force. Thawne admits he made a mistake and tells Iris to reunite her family. Meanwhile, Icicle steals a cryo-atomizer from Tannhauser Industries and kidnaps Caitlin and Carla, planning to eliminate their human sides. Later, Killer Frost fights Icicle, while Barry saves Carla from the cryo chamber. Unbeknownst to everyone, the chamber turns Carla into a meta. Before Icicle can kill Caitlin, Thomas Snow finds the strength to return to his human form. Cicada, who earlier kidnapped her younger self, arrives and fights Killer Frost. Thomas sacrifices himself for his daughter by stepping in front of Cicada's dagger, after which Cicada escapes with the cryo-atomizer. Barry admits he was wrong and he and Iris agree to work together to help their daughter. Elsewhere, Nora emerges from the Negative Speed Force with glowing red eyes.

Nora plans a heist at McCulloch Technologies, who have made weapons from the satellite shrapnel. Needing accomplices who will not be affected by the meta-power dampeners on-site, she recruits Brie Larvan / Bug-Eyed Bandit, Rag Doll, and Weather Witch. After going through the dampeners, the Rogues turn on Nora and threaten to kill all the employees unless the Flash reveals his identity. While Sherloque distracts the Rogues as a hologram of the Flash, Barry, Iris, and Joe show up with guns. Iris and Joe help the hostages escape and take down Rag Doll, while Barry and Nora team up to disable the dampeners and apprehend the others. Nora reveals she was trying to steal a mirror gun capable of destroying Cicada's dagger. She makes amends with her parents and agrees to abandon Thawne's plan. Barry, however, wants to use the gun. Meanwhile, Caitlin and Ralph discover that Cisco's metahuman cure prototypes have been stolen and realize that Cicada can weaponize a lethal version of the cure with the cryo-atomizer. Elsewhere, Cicada works on the cryo-atomizer, envisioning her uncle beside her.

Team Flash decide to gather the metahumans in Central City at the CCPD and distribute the cure to protect them against Cicada. Sherloque goes to get Renee, but she refuses the cure and is sent to safety on his Earth. Nora reveals she is still connected to Grace's mind from using the Memory Machine and feels her anger through the Negative Speed Force. She wants to look through Grace's eyes to locate her, but her parents decide it is too dangerous. Ralph is trying to figure out Thawne's plan, but the others are more interested in stopping Cicada. After Cicada collects the final pieces for her weapon, Barry and Iris agree to let Nora connect to her and expose herself to the Negative Speed Force. She locates Cicada just as she attacks CCPD. Cicada uses the metas' dark matter as a battery for the cryo-atomizer. While the others engage Cicada, Cisco disables the cryo-atomizer. Ralph figures out Thawne's plan just as Barry shoots Cicada's dagger with the mirror gun. In 2049, Thawne's time is up and he is about to be executed. As he is strapped down, it is revealed that his powers are being dampened by Cicada's dagger.

Ralph saves the dagger, which Cicada then reclaims before escaping. After Thawne's plan is explained, Nora realizes she has been played and comes up with a plan to eliminate Cicada without destroying the dagger. The team tracks Cicada to her younger self where Nora enters her mind and with help from a reformed Orlin successfully convinces her to take the metahuman cure. However, the shard in Grace's head counteracts the cure, forcing Barry to destroy the dagger with the mirror gun, resulting in the adult Grace being erased while in 2049, Thawne regains his powers. The entire team confronts and fights Thawne, with Barry and Nora finally subduing him; however, the new daggerless timeline threatens to erase Nora. Thawne escapes after revealing the only way to save Nora is for her to reenter the Negative Speed Force. However, Nora refuses to become like Thawne and is erased while hugging her parents. Sherloque returns to his Earth while Cisco takes the metahuman cure. Captain Singh gets promoted to chief of police and names Joe as his replacement, while also revealing he knows Barry is the Flash. Barry and Iris discover a farewell message from Nora. The date of the crisis in the future newspaper changes from 2024 to 2019.

Moments after losing their daughter Nora West-Allen, Barry and Iris find her message destroyed. Four months later, they have seemingly come to terms with what happened, but the others are not convinced. While recovering Nora's discarded suit at the junkyard, Iris is nearly sucked into a black hole. Her investigation into what caused it leads her to Chester P. Runk, who built a machine to open black holes only to end up catatonic after half of his consciousness was absorbed into it. Even worse, the black hole opens over Central City; much larger than before. Using tech from Nora's back-up gauntlet, Barry dives into the black hole, retrieves Chester's consciousness, and puts it back into him; restoring him and closing the black hole. Meanwhile, Caitlin helps Frost learn how to live her own life and tries to dissuade her colleague Ramsey Rosso from using dark matter to cure his patients. Rosso ignores Caitlin's warnings and tests his cure on himself, only to exhibit metahuman powers. Elsewhere, Barry and Iris learn that the Monitor destroyed Nora's message to discourage Barry from changing his fate during the impending Crisis; telling him the Flash must die so billions can live.

Refusing to give up hope, Barry decides to time travel to the day after he disappeared to find out what really happens during the Crisis. However, an anti-matter barrier prevents him from getting there. After suffering a unique wound, he travels to Earth-3 to see Jay Garrick and his wife, Joan Williams. Using a machine Jay built, they send Barry's mind through the anti-matter wall, causing him to see billions of timelines where the multiverse is destroyed and the one where he dies saving it. The experience leaves him unsure of what to do, though Joe later reassures him his death is not a sign that he gave up. Meanwhile, Cecile takes on a case involving young meta, Allegra Garcia. Her powers tell her she is innocent, so she asks she be released. However, Allegra turns up at a crime scene having seemingly killed someone. Even in spite of Joe telling her how her job works, Cecile still believes Allegra's innocent. Just then, Allegra's meta cousin, Esperanza, attacks CCPD to kill her. Barry defeats her and clears Allegra's name. Following this, Cecile decides to become a defense attorney for metahumans. Elsewhere, Rosso continues to learn more about his powers.

Rosso inadvertently turns gunrunner Mitch Romero into a zombie, leading to him attacking and killing his own crew in search of dark matter to strengthen himself. Barry and Frost investigate, though the former also works to help the latter learn how to go on without him following the Crisis and how to live her life to the fullest. Using Caitlin's memories, Frost immediately suspects and tracks down Rosso, and Barry convinces him to help. Though Rosso nearly steals dark matter while at S.T.A.R. Labs, Barry persuades him not to; bonding over their borrowed time after Rosso reveals he is dying of HLH, which took his mother. Romero gets inside S.T.A.R. Labs, where Rosso learns he can control him before Barry and Frost overdose him on dark matter and destroy him. Meanwhile, Cisco and Iris briefly encounter adventurer Harrison "Nash" Wells, who has come to Earth-1 in search of a substance called "eternium". Ultimately, Barry and Iris come clean with Team Flash about the former's fate in the Crisis while Rosso discovers he can manipulate the blood-like substance Romero produced and use it in his cure; quickly developing a desire for more.

While Rosso steals more blood for his cure, flashbacks show how he once cared for his mother before she was diagnosed with HLH and how he became upset with her for apparently giving up before she died. While Team Flash processes what Barry and Iris told them, Cisco refuses to accept it and vows to save the former. In response, Barry decides to train Cisco to become the new leader of Team Flash after he's gone by working with him to save Rosso. Nash appears and offers his assistance in exchange for a "crypto-circuit" he claims only Cisco can build. The three raid McCulloch Technologies for a regenerating serum, though Cisco pockets it to save Barry instead and claims it was sold off. Barry later finds out and they have a falling out. Barry gives the serum to Rosso, hoping it'll save him, but it does not work; causing Rosso to realize he needs blood flooded with adrenaline to save himself. He attacks the hospital and kills several people even in spite of the Flash and Frost's arrival and escapes. As Barry vows to stop him, he and Cisco mend their friendship. Elsewhere, Nash searches the sewers; tracking the Monitor's movements.

Barry and Iris go on vacation; leaving Cisco in charge while they're gone. Suddenly, Breacher shows up to tell Cisco that Cynthia was murdered by a hacker she was hunting named Echo. Cisco works with Breacher and the Collectors to figure out who Echo really is, only to learn it is him. Breacher nearly kills Cisco, but ultimately relents and chooses to give him an hour to turn himself in. Upon further investigation, Cisco discovers Echo is actually his Earth-19 doppelgänger, who used their shared face to frame his Earth-1 counterpart. After a confrontation, Cisco manages to trap Echo so the Collectors can arrest him. Breacher apologizes to Cisco as both realized Cynthia lured Echo to Earth-1 knowing the latter would be able to bring him to justice. Meanwhile, Rosso offers Caitlin immortality in exchange for joining him, but she declines. He disavows her as a friend and escapes. Elsewhere, Joe tracks Nash in the sewers, but both become trapped in it until Ralph rescues them. After Team Flash offers to help, Nash reluctantly agrees and tells them he knows how to save Barry from his impending death.

Ralph Dibny follows up on a lead regarding Sue Dearbon, who he has been searching for since the past summer, in Midway City. Barry, wishing to help Ralph live without him following the Crisis, asks to come along. While infiltrating a criminal gala, Barry tips their hand and arouses the suspicions of the host, Remington Meister; who allied himself with an escaped Esperanza. While searching for Dearbon, Barry accidentally gets himself and Ralph captured and left to die. As Ralph teaches Barry that both of their identities are important, they manage to escape, defeat Esperanza, and foil Meister's auction; though they do not find Dearbon. Later, Barry holds a press conference to officially recognize Elongated Man as one of Central City's protectors. Meanwhile, Nash asks Allegra for help, requiring her abilities to illuminate a wall filled with eternium, which will destroy the Earth if struck. She hesitates, fearing she will turn out like Esperanza, but Nash assures her that will not happen unless she chooses to, so she assents. Elsewhere, Cecile helps Chester get his life back now that his powers have stabilized. After Ralph tells Iris Esperanza and her mysterious benefactors turned up at the gala, Rosso attacks him.

Despite Ralph's best efforts, Rosso drains his blood. Frost gets Ralph to S.T.A.R. Labs, where Barry gives him a blood transfusion. However, a trace of Rosso's blood enters Barry's bloodstream; causing him to pass out. The Speed Force, in the form of his mother Nora Allen, tells him that Rosso's blood contains his consciousness and is slowly infecting him as well as grants him access to Barry's mind; including knowledge of his secret identity and impending death. Using his memories against him, Rosso tries to convince Barry to join him; promising him the power to avert not only his death, but countless others. The Speed Force tries to dissuade Barry, but accidentally provokes him when he surmises he was their pawn and he will never get what he wants while serving it. Cisco and Frost eventually revive Barry, but when Iris comes to check on him, she quickly realizes it is not him. Fully infected, Barry attacks his friends and reports to Rosso, who is ready to enact his masterstroke. Elsewhere, Iris, Kamilla, and Allegra investigate the organization that turned Esperanza into a killer. They learn the group's name, Maelstrom, but their only lead is mysteriously killed.

With the Flash under his control, Rosso attacks Central City and converts most of its citizens into his "Blood Brothers and Sisters". Cisco and Iris argue over how to save Barry and stop Rosso, but both of their plans fail. However, Rosso chooses not to convert them in favor of enacting the final phase of his plan; taking the particle accelerator to spread his blood across all of Central City. As he makes his way inside, Cisco and Iris realize that during their last encounter, Barry used his connection with Rosso to secretly save them and tell them how to beat him. Using a combination of Rosso's blood, the particle accelerator, and Allegra's powers, Team Flash subvert Rosso's plan to cure Central City of his influence. With his plan foiled, Rosso transforms into a blood monster to kill the Flash and begin anew, only to be distracted by a hallucination of his mother long enough for the speedster to trap him in Chester's prison. While Rosso is remanded to A.R.G.U.S.'s custody, Team Flash spend their last moments before Crisis together just as red skies loom over them. Meanwhile, Nash uncovers a wall of symbols before a blinding light pulls him inside.

Ray Palmer's "Paragon detector" identifies Barry, J'onn J'onzz, and Ivy Town scientist Ryan Choi as the remaining three, so Ralph, Iris, and Ray leave to recruit Choi. After the Monitor restores Cisco's powers, Team Flash and Nash (now Pariah) return to the chamber the latter found; where they find an anti-matter cannon and Earth-90's Flash powering it. Cisco successfully frees him, but the cannon starts going critical, so Pariah recruits Black Lightning from another Earth to help contain the energy. As Barry prepares to destroy the cannon, Earth-90 Barry stops him so he can sacrifice himself in his place. Elsewhere, John Constantine, Mia Smoak, and John Diggle visit Lucifer on Earth-666 to get Oliver Queen's soul back, which they find in Purgatory. Before they can leave, Jim Corrigan appears so he can pass the Spectre's power onto Oliver. He accepts and Constantine's team is sent back without him. While the heroes regroup, the Anti-Monitor sends a brainwashed Harbinger to attack them and kill the Monitor so he can finish destroying the multiverse. Before he's killed, Pariah teleports the Paragons to the Vanishing Point; where they learn Lex Luthor used the Book of Destiny to replace Earth-96's Superman with himself.

Following Oliver's sacrifice while averting the Crisis, Iris, Allegra, Kamilla, and Cecile form Team Citizen to investigate a secret organization called Black Hole as well as McCulloch Technologies. While investigating the latter, its CEO Joseph Carver denies any connection to the former. Despite this and Cecile's legal advice, Iris writes a story on their work, prompting Black Hole to hire metahuman assassin, Kimiyo Hoshi, to kill her. Meanwhile, Diggle arrives in Central City to give Barry the mask he gave Oliver the first time they met. Barry notices traces of Mirakuru serum on it and believes it contains a warning Oliver left behind regarding a new threat and heads to Lian Yu, where Diggle helps him come to terms with Oliver's death. Back at S.T.A.R. Labs, Team Citizen sets up a trap for Hoshi while Iris blackmails Carver. Under duress, he calls off the bounty and suggests his missing wife Eva McCulloch is involved. While investigating further, Iris is pulled into a mirror. Elsewhere, still reeling from what happened during the Crisis and feeling guilty for taking the metahuman cure beforehand, a newly depowered Cisco decides to leave Team Flash to catalogue all the changes that occurred.

Barry and Iris' Valentine's Day date is interrupted by Amunet Black, who steals a valuable briefcase containing a mysterious device. The two track Amunet to Ivo Labs, where she is confronted by her ex-boyfriend, Goldface, who gets away with the device she was attempting to steal. Barry and Iris witness the confrontation before leaving with the briefcase. After a brief argument with Barry over life choices, Iris allies herself with Amunet. Flash later encounters Amunet and Goldface while they're fighting over a Rappaccini's Daughter flower they both want before stopping them by exposing them to its pollen; allowing the two crime lords to reconcile, as do Barry and Iris. Unbeknownst to him, the Iris that he worked with the entire time is an impostor, as the real one is still trapped in the mirror at McCulloch Tech. Meanwhile, Frost convinces Allegra to reconnect with her ex-boyfriend. After Nash provides additional advice, he sees hallucinations of his doppelganger, Harry Wells.

In the mirrorverse, Iris meets Eva, who had been trapped there ever since the particle accelerator knocked her in. Recalling Sam Scudder, Iris suggests using liquid nitrogen to shatter the mirror so they can escape, but it fails. Distressed by this, Eva discovers she can control the mirror. Iris' double asks for access to the mirror gun, but Barry denies her. She heads to the S.T.A.R. Labs archives to retrieve it, but fails to after bumping into Nash while he was retrieving Harry's journal. Meanwhile, after months of searching, Ralph finally tracks down Sue, but she claims she cannot go home because she is being targeted by gangster John Loring. Ralph joins forces with her to take down Loring, revealing his secret identity in the process. However, Sue double-crosses Ralph to steal a diamond. Loring catches Sue red-handed, but Ralph saves her. Suddenly, Esperanza arrives to kill Sue. The two women fight until Sue tricks Esperanza and Ralph in order to escape. Elsewhere, Joe comes to Barry with evidence of a mole inside CCPD, Joe tells Barry that only family can be trusted. In response, Barry is convinced to give "Iris" the mirror gun. While investigating the diamond, Sue uncovers Black Hole's symbol.

While looking for the cemetery where his parents are buried, Barry finds Hartley Rathaway robbing a jewelry store. Kamilla and Chester provide assistance as the rest of Team Flash is busy, but Hartley escapes. While updating Gideon, Barry accidentally ends up in Grodd's mind while the latter is still in his neural inhibitor-induced coma. Grodd tells Barry that because of the Crisis, he wanted to make amends for what he has done and return to Gorilla City to live in peace. Barry does not believe him, but when he tries to escape, he is stopped by the "gatekeeper", a manifestation of Solovar. After Barry reconciles with Grodd, they work together to defeat Solovar while Chester helps separate their minds. Following this, A.R.G.U.S. arranges for Grodd to be released on probation. Meanwhile, Iris and Eva make another attempt to escape the mirror dimension, but the latter burns her arms. When Iris leaves to get bandages, Eva contacts mirror Iris, who suffered the same injuries while working for her before Eva heals them. Elsewhere, Allegra learns she had a doppelgänger who worked for Nash. When Nash tries to explain himself, he hallucinates another doppelgänger of his, Sherloque Wells, warning him that "he is coming".

Wally West and Cisco return to Central City, with the former confronting Barry over Oliver enhancing his speed during the Crisis.[a] As a result, the Speed Force dies, and in a few weeks, all speedsters will permanently lose their speed. Meanwhile, Frida Novikov, a metahuman who can manipulate time, attempts to exact revenge against those who ruined a past crime spree she committed. Dubbing her "Turtle II", Cisco develops Velocity-X to negate her powers, and with help from Flash and Kid Flash, Joe eventually manages to arrest her. Following this, Cisco is attacked by Eobard Thawne, who took possession of Nash's body, but cannot access his speed as his host does not have powers. Cecile incapacitates him, allowing Team Flash to imprison him in the pipeline. After Thawne reveals that he still has access to the Negative Speed Force, Barry gets the idea to create an artificial Speed Force to save himself. Before he leaves, Wally voices his suspicions about Iris to Joe. Elsewhere, Kamilla discovers evidence of mirror Iris' true nature, but the duplicate shoots her with the mirror gun to silence her.

Joe informs Chief Singh of the CCPD mole, but he is skeptical. Elsewhere, Cisco gives Barry a "Speed Gauge" to monitor his waning powers before building a device to "exorcise" Thawne, who was fused with Nash alongside the other Wellses following Crisis. While inside Nash's head, Cisco, Cecile, and Barry learn that Thawne is using Nash's traumatic past with Allegra's doppelgänger, Maya, against him. With this knowledge, they help Nash come to terms with her death and expel Thawne. Meanwhile, Eva sends Mirror Iris and Mirror Kamilla to steal a Prismatic Refractor from Mercury Labs, only to find Black Hole operative, "Sunshine", has beaten them to it. They call in Frost and Flash, but despite using Velocity-X, Flash's speed falters and Frost is nearly killed, though CCPD intervene and force Sunshine to escape. After "Iris" reminds him of the idea of limits, Barry works with CCPD to trap Sunshine in his lab with the windows shuttered, blocking her powers. While arresting Sunshine, Singh suspects she was the mole because of her powers. Following his experience with Thawne, Barry decides to use Nora West-Allen's journal to create his artificial Speed Force while the mirror clones deliver the refractor to Eva.

As Iris becomes acclimated to the mirror dimension, she reveals to Eva that her husband is the Flash, who might be able to save them if they can communicate with him. Eva directs Mirror Iris to ensure Barry loses his speed. Meanwhile, Carver hires Rag Doll to kill Joe. After his car is sabotaged, Singh urges Joe to go into Witness Protection; but he refuses. Rag Doll attacks Joe directly, who gets shot when Barry fails to catch all of the bullets. While Joe tries and fails to get evidence on Carver, Rag Doll kidnaps Cecile. Barry battles Rag Doll while Joe rescues Cecile. These incidents convince Joe to take up Singh's offer while Singh is revealed to be another of Eva's duplicates. Eva has a mirror sent to Carver to give him one last chance to apologize to her, but he refuses and destroys the mirror. Mirror Iris is furious that Barry failed to protect Joe and that she could not say goodbye to him before kicking him out just as his Speed Gauge drops to the danger zone. Meanwhile, Ralph and Cisco find Sue robbing Carver's banks, who she claims is blackmailing her parents. She apologizes for manipulating Ralph, but continues to reject his help.

Barry becomes suspicious of "Iris", and with a skeptical Cecile's help, discovers Kamilla's evidence. However, Eva switched his equipment, causing Team Flash to believe he is the fake and lock him up, though Cecile frees him. The mirror duplicates approach Rosso for his blood in exchange for freeing him, with Mirror Kamilla sacrificing herself to do so. Though Rosso donates his blood, he chooses to remain imprisoned as part of his own plans. Iris discovers Eva's treachery, but gets captured. Mirror Iris gives Eva the blood and wounds a weakened Barry. While watching the battle, Iris taunts Eva with her love for Carver, causing Eva to suffer a mental breakdown and impair Mirror Iris. Barry encourages Mirror Iris to live for herself, but Eva shatters her before stepping out of the mirrorverse and wounding Barry further. Despite his weakened state, Eva chooses to leave and enact her plans instead of killing him. As he heals, Barry and Iris promise to hold on for each other's sake before the latter searches for Kamilla and Singh. Meanwhile, Cisco and Ralph find Caitlin suffering from a hypothermic reaction due to her fight with Sunshine. Once she counters it, Caitlin decides to visit her mother.

Barry visits Joe to tell him what happened before telling Team Flash about the mirror clones. Following attacks by four incommunicable Godspeed drones throughout the past year, Godspeed himself seemingly attacks so he can drain Barry's speed using thunderous vibrations. Realizing they need a vibrations expert, Barry finds Hartley, who resents him in the post-Crisis timeline after he destabilized his henchman and boyfriend, Roderick's, molecules years prior. The two reconcile and bond over taking responsibility for their loved ones before learning that Godspeed acquired his drones' speed and taken hostages. Barry and Hartley join forces to combine their powers and defeat Godspeed. Though they discover it was another drone and that it was sent by someone wanting infinite velocity, they are able to use its "charged sound" to save Roderick. Following this, Cisco becomes inspired to build a perpetual motion machine using Atlantean materials to save their friends from the mirrorverse. Meanwhile, Iris finds Kamilla, but begins to succumb to neural dissonance like Eva did, Ralph helps Frost come to terms with properly meeting Caitlin's mother, and Eva prepares to confront her husband.

Barry warns Carver about Eva after Mirror Singh destroys Black Hole's warehouse, but he rebuffs him until he learns Eva captured his metas, forcing him to accept. Mirror Singh offers to return Iris in exchange for Carver, but Nash has them flee before he can answer. Hiding at McCulloch Tech, Ralph discovers that Sue joined Black Hole to kill Carver, so he tries to dissuade her. Having sided with Eva, the Black Hole assassins disable the security system and attack. As Nash, Allegra, Elongated Man, and Sue battle them, Mirror Singh sacrifices himself to get Eva inside and knock out Barry. Despite the Flash's best efforts, Eva kills Carver and takes her company back, though she lets Team Flash go. Eva reveals herself to the public, claiming she was held hostage by a crime syndicate and Carver died saving her. With Carver dead, Sue celebrates her family's freedom until Ralph reveals Eva framed her for his murder. As Joe returns from witness protection, Team Flash plan to rescue their friends from the Mirrorverse while Caitlin departs with her mother for treatment. Meanwhile, Iris is able to concentrate enough to find Singh, but the neural dissonance intensifies until she inexplicably vanishes.

Having cryogenically frozen himself to preserve his 1% Speed Force energy, Barry Allen awakens when Eva McCulloch is spotted destroying Black Hole's remnants. He tries to convince her to stop and release his wife, Iris West-Allen, from the Mirrorverse, but to no avail as Eva ends her latest attack by destroying Sam Scudder, her first mirror duplicate, in front of Rosalind Dillon. Cecile Horton interrogates Dillon, learning that she is working with Eva. Using her empath abilities, Cecile gets Dillon to reveal that Eva plans to use a bomb to destroy a Black Hole plane over Central City. Meanwhile, Nash Wells and the Wellses occupying his mind realize they can activate Barry's Artificial Speed Force (ASF) generator, but it would result in Nash's death. He attempts to explore other methods, but with time running out, Nash sacrifices himself and the other Wellses to restore Barry's speed. Barry saves Central City and intends to inform his friends about Nash's sacrifice. Elsewhere, Iris attempts to escape the Mirrorverse while Eva discovers she is also a mirror duplicate and that the real Eva died in the S.T.A.R. Labs particle accelerator explosion.

After mourning Nash and the Wellses, Barry and Cisco Ramon work towards saving Iris, Kamilla Hwang, and CCPD Captain David Singh by opening a portal to the Mirrorverse. Barry discovers the ASF granted him speed-thinking, allowing him to predict outcomes while causing him to become impersonal. Using his new abilities, he exposes Eva as an imposter on live television, forcing her to flee. However, a choice emerges: save Iris or save Kamilla and Singh. When Barry prioritizes saving Iris exclusively, Cisco, Frost, and Allegra Garcia join forces to stop him, but fail. Meanwhile, Iris plans a rendezvous with Kamilla and Singh, but they experience seizures. When Barry opens the portal, he forces Iris to come through alone, but she also experiences seizures. This shocks Barry into realizing what he has done and disabling the ASF. Elsewhere, a maddened Eva schemes to take over the world by replacing everyone with mirror duplicates while a confused Earth-1 Harrison Wells materializes where his corpse was 20 years after his death.

Eva begins replacing people with mirror duplicates. Sue Dearbon and Ralph Dibny return with evidence to exonerate her of Eva's crimes, but he became a blob after McCulloch Technologies was destroyed. Though Eva convinces Barry he cannot win, Wells comes to S.T.A.R. Labs and reminds him that he is the Paragon of Love. As Barry checks on Iris, he revives her. Barry and his team re-activate the ASF and fight the duplicates while Barry revives the original Speed Force before he and Iris convince Eva to stand down. Showing remorse, Eva tries to stop her duplicates, but they become too powerful, so she joins forces with Barry and Iris to destroy them. After freeing her prisoners, Eva leaves for the Mirrorverse to start anew. Claiming that he can now perceive all of his life at once and travel freely through time and space, Wells decides to put himself in a time loop so he can live peacefully with his wife, Tess Morgan, while an exonerated Sue and a recuperating Ralph travel the world to stop other Black Hole-esque organizations. 18 hours earlier, when Barry and Iris revived the Speed Force, they unknowingly released four differently colored lightning bolts.

One week after Eva's attack, Central City begins to rebuild as Iris and Allegra work to cover the Mirrorverse incident for the Central City Citizen. The former struggles to face the trauma from her ordeal in the Mirrorverse while Barry grapples with his guilt over not deducing Mirror-Iris was an impostor. Meanwhile, Abra Kadabra returns and lets himself be arrested by A.R.G.U.S. so he can complete an anti-matter bomb that he intends to use on Central City in retaliation for his family being erased from existence following the Crisis and to make Barry suffer. Barry successfully talks Kadabra into disabling the bomb, but they are suddenly attacked by a monster, which absorbs the bomb. Kadabra attempts to save Barry, but is killed by the monster. It nearly kills Barry as well, but it winces in pain and runs off. Allegra is promoted to staff writer and Iris joins a Mirrorverse support group. Elsewhere, after both suffering from headaches, Frost and Caitlin Snow reveal to Cisco that they have separated from each other.

Due to Eva using her Mirror Gun on Caitlin, Frost's metahuman DNA created a new body. Caitlin and Frost argue over whether to re-merge or stay separated, but eventually agree to the latter. Barry is visited by the Speed Force, as his mother Nora Allen, carrying the same energy signature as the monster that attacked Barry and Kadabra, nicknamed "Fuerza". Barry gives the Speed Force his speed gauge to monitor its health before fighting a new enemy, Psych, who is using fear waves to trap everyone in Central City in perpetual nightmares. Barry is injured by one involving Eobard Thawne and Savitar. Team Flash uses Barry's speed, Cecile's abilities, and Clifford DeVoe's hover-chair to produce a courage wave to stop Psych. However, he disappears and Barry returns to his cryogenic chamber to recover. Elsewhere, Kristen Kramer, a liaison from the Governor's Municipal Logistics Commission, arrives at the CCPD, where she tells Joe that she is there to arrest Frost. Later, the Speed Force says that she was attacked by Psych and Fuerza and both of them are "like her".

Cisco and Chester P. Runk start creating devices to detect Fuerza and Psych. While setting one near Chester's hometown however, they are trapped in a time loop of the day before Chester's dad, Quincy, died in a car crash. With Quincy's help, Chester and Cisco build a device to detect and protect themselves from the "time god", Deon Owens, a high school quarterback who is attempting to prevent an injury that ruined his football career. Chester convinces him to let go of his past and that the future remains unwritten, causing Deon to realize he can change everyone's futures before vanishing, ending the time loop, and returning Chester and Cisco to the present. The two fail to find Deon, though they believe he is unaware of the Speed Force's revival. Cisco later discovers three other "forces", names them Still, Strength, and Sage, and determines Deon, Fuerza, and Psych are their respective conduits. Meanwhile, Barry emerges from his cryo-chamber and Iris bonds with the Speed Force before inviting it to stay with her and Barry. Elsewhere, Chester begins working on his father's old project while Joe warns Frost of Kramer, though Frost refuses to hide.

Despite healing from his battle with Psych, Barry's powers glitch whenever he is around the Speed Force. It tries to help, but its appearance unsettles Barry. Meanwhile, a microchip is stolen from Ivo Laboratories and a driver is killed by someone with ice powers. Kramer believes Frost is the culprit and issues a warrant for her arrest. Despite being asked not to, Frost visits her old bar to find information on the criminal from the new bartender, Mark Blaine. Now calling himself "Chillblaine" however, he reveals that he created the microchip before he was fired and used his own cryogenic technology to replicate Frost's powers and frame her. He defeats her, but she stabs him. Barry and Allegra arrive and they provide medical attention while Frost reveals she recorded Blaine's confession. As Kramer and the police arrive, Frost chooses to turn herself in and surrenders peacefully. Barry and "Nora" acknowledge that she is different from the Speed Force entity he knew before and the two vow to fight the other Forces.

Barry and "Nora" leave to combat Fuerza in Keystone City and meet Alexa Rivera, but "Nora" believes Alexa is Fuerza and scares her. After gaining her trust, Barry learns Alexa has been blacking out whenever she gets angry. She agrees to go to S.T.A.R. Labs, where Team Flash confirms she is Fuerza. "Nora" attacks Iris, and "Nora" uses Barry's powers to kill Alexa. Meanwhile, at Frost's trial, Kramer attempts to force her to take the metahuman cure instead of prison time. Distraught, Caitlin has her mother, Carla Tannhauser, test if the cure would harm Frost. Cisco helps Caitlin and Allegra break into CCPD to neutralize the cures. However, Kramer accuses Frost of the act and reveals another vial she procured from A.R.G.U.S. Tannhauser confirms the cure will not harm Frost and urges her to take it, but Frost is worried she will lose her identity. Kramer reveals to Frost that she lost a platoon to a metahuman during "Operation Griffin". In court, Frost expresses how unjust forcing the cure on someone is and requests life imprisonment without parole, which the judge agrees to.

"Nora" tells Iris and Barry that they created the other forces and vows to kill Psych and Deon. Barry wants to travel back in time to remove their connections to the Forces, but Iris and Cisco disagree. Cisco gives Kamilla a camera that can detect the forces, which shows a connection between them and Iris, allowing Team Citizen to track down "Nora". Barry, Cisco, and Chester enhance the tachyon device to extract the Forces' particles before Barry retrieves Wells to create a "time bubble" to protect the timeline. Realizing Barry's intentions however, Deon arrives and destroys the device. During Team Citizen's search, they are ambushed by Psych, who gives Iris nightmares of "Nora". Chester fixes the device while Joe tries to dissuade Barry from his plan, but Barry and Wells go back in time regardless. The extraction revives Alexa and erases Psych and Deon in the present. However, Barry destroys the device to undo the changes upon realizing his allies are right. Caitlin notices Alexa's revival, so Barry and Iris use their connection to the Forces to revive her. Wells leaves and Cisco and Kamilla realize they need to leave Central City while "Nora" confronts Deon.

While "Nora" reasons with Deon, Psych attacks billionaires. Iris learns Psych is Bashir Adil Malik, a former rich kid who was abandoned by his adoptive and biological parents. Kramer returns to the CCPD and asks Joe to bring in Barry to discuss metahuman transfers after getting information that Rainbow Raider went missing. She later reveals she had created bullets containing the metahuman cure with the governor's approval. Cecile advises Joe that Kramer must stop her hunt on her own, leading to Joe resigning from the CCPD to remain righteous. Concurrently, Barry, Cisco, and Caitlin train Alexa to control Fuerza, though Barry's over-determination to have Fuerza fight Psych results in Alexa injuring Cisco and becoming unmotivated. To help her, Caitlin gives Alexa a device to communicate with Fuerza. After Fuerza defends Barry from Psych, Barry convinces Psych to come to S.T.A.R. Labs. However, Deon and "Nora" arrive and attack Iris, Alexa, and Psych.

Iris, Alexa, and Bashir fake their deaths and escape using an illusion. Bashir convinces Alexa to go back and fight "Nora", who conjures a storm that knocks out Cecile and sets prisoners at Iron Heights free, though Frost stops Chillblaine. After failing to recruit Deon, Barry confronts "Nora", but she reveals that the other forces conjured the storm. Deon betrays "Nora", but is forced to retreat. Joe proves to Barry and Iris that they are not bad parents and they reconcile with Alexa, Bashir, and Deon. They overpower "Nora" while the storm nears critical mass and threatens to destroy everything. Bashir and Deon show "Nora" a future completely empty of others, overwhelming her and convincing her to stop. With time running out, the forces aid Barry so he can run fast enough to stop the storm. The forces reconcile and depart to expand the Speed Force while Cecile regains consciousness. Frost returns to Caitlin's apartment after the district attorney's office grants her time off for good behavior for her efforts during the storm and admits to having a crush on Chillblaine. While trying to process everything, Barry and Iris decide to start a family.

Cisco accepts a job at A.R.G.U.S. and reveals that he and Kamilla are moving to Star City. Barry and Caitlin hide their feelings about Cisco leaving so as not to dissuade him, but this upsets him. Elsewhere, metahuman Carrie Bates, later nicknamed Rainbow Raider 2.0, tricks a bank teller into giving her money by placing him in a euphoric state. Barry and an overenthusiastic Cisco confront Bates using a device they used to stop the original Rainbow Raider, but Bates destroys it and sways Cisco, who ruins a second confrontation with Bates, allowing her to sway Barry. Chester returns them to normal, and Cisco has a tearful reconciliation with Barry and Caitlin. After Bates secures a blimp she can drop money out of to "save people from the system," Barry convinces Bates to stand down and work on Mayor Sampson's economic development committee. Cisco gives his tech to Chester before the former and Kamilla are given going-away parties. After revealing she is about to close a case, Cecile vows to find a psychic mask manifesting in her reflection.

After revealing gaps in Kramer's past to Joe, Cecile, under the control of Psycho-Pirate's mask's "psychic spirit", sends Barry's consciousness to a mindscape where he finds the real Cecile's consciousness, which had been trapped since the Force Storm two weeks prior. "Psycho-Cecile" tricks Iris, Chester, Caitlin and Sue into stealing the mask from the Central City Museum, which she uses to gain enhanced psychic powers. She later uncovers DeVoe's hover-chair in order to amplify and feed off of Cecile's powers. In the mindscape, Cecile reveals to Barry that they are in a memory of a psychiatric ward in Texas where she was a patient following her mother's death, which depressed and institutionalized her. Iris and Chester destroy the hover-chair and Cecile overcomes her grief, allowing her and Barry to reclaim their bodies while the mask is confined at A.R.G.U.S. After reuniting with Cecile, Joe reveals Kramer had worked with her enemies and intentionally led her unit into an ambush during Operation Griffin.

As Barry and Iris go on vacation, Allegra's cousin Esperanza Garcia / Ultraviolet resurfaces to kill a Dr. Olsen, who contributed to turning Ultraviolet into an assassin at the cost of her voice, and attack Allegra to dissuade her from looking for her. Believing that there is some good left in her cousin, Allegra and Sue eventually track Ultraviolet and Olsen to a warehouse, where Allegra unlocks her powers' full potential and defeats Ultraviolet. Olsen is sent to jail while Caitlin, Allegra, and Sue offer to help Ultraviolet and restore her voice using Olsen's research. Meanwhile, Joe offers Kramer his help, but she refuses and threatens to have him arrested. During a second meeting however, she reveals it was her adoptive brother, Adam Creyke, who led her men into the ambush, though she blamed herself ever since. She eventually asks Joe to help her find Creyke. Elsewhere, Frost meets with Chillblaine, who claims he has been released from prison for turning state's witness, much to Frost's surprise.

Barry dreams about his future daughter Nora West-Allen, leading him to believe Iris is pregnant, so he develops a way to test Iris' hCG levels. Despite Barry wanting to keep it a secret, Cecile and Chester find out. Meanwhile, Frost reluctantly brings Chillblaine to S.T.A.R. Labs after he gets injured in a fight and returns his technology. Suddenly, six modem-speaking Godspeed clones arrive in Central City to target Barry, so Chester creates a translating algorithm and activates S.T.A.R. Labs' defenses. When the clones break in, Chester flees to the Time Vault and has Gideon boost a modem-speak signal to confuse them, allowing Barry, Chillblaine, and Frost to combat them. When one of the clones destroys Gideon, Barry flees into the city with all of the clones pursuing him, but six more appear and attack the first six before all of them disappear to recharge. While recovering, Frost and Chillblaine share a romantic experience until he escapes while Barry learns Iris is not pregnant. Elsewhere, Cecile helps Caitlin remove Esperanza's Black Hole chip and Joe and Kramer are attacked while staking out Creyke's boat.

Barry dreams about Nora again, who warns him that her future is in danger. John Diggle arrives and helps Barry trap a Godspeed clone, who reveals that they are searching for the "prime" August Heart, and requests Barry's aid in killing him, but escapes after Barry refuses. Diggle convinces Barry to go to 2049 to check on Nora, but he is knocked out of the Speed Force by Godspeed clones. Barry then finds Deon protecting Iris, who is inexplicably phasing through temporal planes. Diggle, Cecile, and Frost find an amnesiac Heart, but soon make him remember his identity. Following this, Diggle vows to resolve something he has "been putting off". Meanwhile, after Caitlin treats her, Esperanza requests Allegra's help in stopping other Black Hole remnants, but Allegra refuses. However, Barry's actions prompt Allegra to join Esperanza, but Esperanza is killed. Elsewhere, Joe and Kramer trap their attacker, Creyke, who reveals he betrayed Kramer and the military as revenge for experiments he endured due to his abilities. Joe stops Kramer from killing Creyke and they arrest him. Afterwards, Nora arrives from 2049 alongside Bart Allen, Barry's future son.

Barry allows Bart and Nora to stay in the past and join him in fighting off a squad of Godspeed clones. After they target Bart, he explains that he considers Godspeed "his Thawne" since he witnessed Godspeed murdering Jay Garrick, who had always encouraged Bart's impulsive attitude. While Barry attempts to contact Wally West for help, Iris returns. After several losses against the clones, Barry and Iris decide to bench Nora and Bart. However, rebel clones capture Jay in Keystone City while he was recovering his speed and demand Bart in exchange for his life. Bart leaves to fight them, but he is knocked out and nearly killed by the clones. Barry and Nora rescue Jay and Bart while Cisco arrives and traps the clones. Meanwhile, Chester asks Allegra for help with charging a device to remove the clones' speed and consoles her upon learning of Esperanza's death. Meanwhile, Joe and Kramer turn Creyke over to the FBI, but return to witness many of Central City's citizens fleeing to escape the "Godspeed War". Afterwards, Cecile helps Barry enter Heart's mind, where he encounters a version of Heart with his memories.

Godspeed demands "organic speed" in exchange for ending the war. The Speed Force reawakens Bart and grants Iris super-speed, and they fight the Godspeed clones alongside Team Flash. However, the Speed Force is forced to retreat when the clones begin to feed off of her energy, but Allegra arrives with Chester's device and removes the clones' speed. Barry decides to grant Heart's request, restoring his memories. Against Cecile's urging, Heart merges with the clones. Suddenly, Eobard Thawne arrives and incapacitates Heart and makes a failed attempt on Barry's life before escaping. Heart is sent to Iron Heights with his memory of Barry's identity removed. Meanwhile, after using super-speed to rescue Joe from an attack, Kramer learns that she is a metahuman with the ability to mimic others' abilities like she did with Creyke and leaves with a new perspective on law enforcement. Barry and Iris renew their wedding vows in front of their friends and family.

In 2031 Central City, psychic alien Despero witnesses the end of the world. Six months after the Godspeed war, Barry Allen's skills have gradually improved. After stopping a train collision in record time, he apprehends the Royal Flush Gang during a cryptocurrency heist. Iris West-Allen heads the larger and stronger Central City Citizen Media and interviews Kristen Kramer, who has disbanded the meta-task force. She promotes Allegra Garcia, who struggles to control her new staff, but is able to shift their focuses to the voice of the people. Meanwhile, Ray Palmer arrives in Central City for a tech convention, and Chester P. Runk surprises him with a group of tech start-ups, but Ray turns them down. Suddenly, Despero arrives and attacks the tech convention. He attempts to kill Barry, stating that he is responsible for the end of the world. Ray suits up as The Atom and sends him away. Cecile Horton confirms that Despero was telling the truth. Later, Ray decides to create an organization in Chester's father's name that will help new start-ups and leaves. Barry gives his identity to Despero, who gives him one week to prove his innocence.

Despero informs Barry that he will lose himself to madness. The following day, Barry investigates an insane security guard, but Kramer forces him to turn in his badge over a federal investigation suggesting that he was a mole for Joseph Carver. Later, S.T.A.R. Labs is raided and shut down after a radiation spike, so Barry has Gideon erase everything. Alex Danvers assists Team Flash in researching Despero and learn about his home planet of Kalanor that was destroyed by an evil despot, and his power source, the Flame of Py'tar. Frost asks Chester to build a weapon to harm Despero, despite his pacifism. With a hint from the guard, Barry goes after psychic meta-criminal Xotar. She causes him to go insane and attack his team, but later depowers her during a jewelry heist. Barry suggests they celebrate with Joe West, but is informed that he died six months prior. News footage shows Barry attacking residents of Central City after Xotar had been depowered, but he does not remember this or Joe's death. Despero arrives to kill Barry, but the team allows him to escape to the Hall of Justice, where he meets with Jefferson Pierce.

In compliance with the Injustice Protocols, Barry asks Jefferson to remove his powers. He begins to, but stops when Barry mentions Despero. Barry lashes out at Jefferson, but is eventually convinced to stand down. Meanwhile, Iris suspects that Barry was framed and that Joe's death was set-up. She investigates with Allegra, discovering a unique set of coincidences that suggest foul play. She begins to see temporal particles and meets with Deon Owens, who discovers that someone tapped into the Negative Still Force to change the timeline and kill Joe. Concurrently, Cecile coerces Rosalind Dillon into helping her find Barry. Dillon tells Cecile to suppress her grief, but Caitlin Snow convinces her to embrace her love instead. Despero turns on the particle accelerator, absorbs its power, and attacks Cecile's group. He learns Barry's location and travels there, but is held off by Jefferson, Iris, and Deon. Deon informs Barry of his findings and sends him to 2031, where he witnesses a future Iris celebrating her engagement to Eobard Thawne alongside Team Flash, Alex, Ryan Choi, and Ryan Wilder, who are unhappy to see him.

Barry finds that he is the Reverse-Flash in this new timeline. Thawne reveals that he killed Joe and framed Barry for the attacks in Central City, then traveled back in time to kill Barry as a child and became The Flash. At midnight, the Reverse-Flashpoint timeline will solidify and Barry will disappear. Barry partners with this timeline's Damien Darhk and plots revenge against Thawne, but Darhk learns Barry's true nature and helps Barry restore the original timeline upon learning that his daughter Nora Darhk is alive in it. Meanwhile, Wilder visits Iris while she struggles to write her vows to Thawne. Alex helps Chester and Allegra admit their love for one another, and convinces Choi to love again. The speed required for Barry to return to 2021 will cause Armageddon through extinction-level natural disasters, so Barry visits Iris to say goodbye. He is intercepted by Thawne, but Iris lets him escape. Thawne chases him while Darhk holds off Frost, Chillblaine, Choi (as The Atom), and Sentinel. As Barry returns to 2021, Thawne's changes are undone and Barry tells Despero to check 2031 for himself. Thawne arrives in 2021 in the Time Vault as the Reverse-Flash.

Barry reunites with Joe, but the two are interrupted by Darhk whose erasure is being delayed due to his Time Stone. Thawne attacks CCPD, but is stopped by Barry and Mia Queen, who is searching for her brother William Clayton. Thawne asks Barry to save him from his own erasure. Despero returns and urges Barry to let Thawne die, but Joe convinces Barry and Iris to let him live. Despero takes control of Mia and has her hold off Team Flash while he threatens to destroy Central City to take out Thawne. Iris and Cecile help Mia regain control while Barry deduces that Despero was the despot on Kalanor. With technology from Chester, Barry depowers Despero and sends him away. Barry then drains Thawne's speed to prevent his erasure and has him remanded to A.R.G.U.S. custody. During a celebration, Iris helps Mia with a lead on William and convinces her to visit Felicity Smoak. Darhk gives his Time Stone to Joe and bids farewell to his daughter Nora who appears in his place. In CCPD, the timeline changes to show Bart Allen and Nora West-Allen in a photograph with Eddie Thawne from 2014.

After their parents' vow renewals, Bart and Nora return to 2049 to find Jay Garrick alive and Joan Williams erased. Their and Godspeed's overuse of the Cosmic Treadmill caused temporal shifts, so they travel back to the earliest one on December 31, 2013 to when Joe is shot during a jewelry heist. While posing as intern CSIs on a coffee run for Eddie, they meet a girl named Avery who is studying quantum mechanics. Bart rescues Joe from being shot, but this only changes the timeline more as metahuman Mona Taylor (who will become Queen of the Royal Flush Gang) eavesdrops on their conversation and plans a deadly heist. With help from Avery, Bart and Nora learn that they cannot stop the heist, but they can stop the casualties. Bart evacuates the building, but is injured by Queen, though Nora is able to remove all of the bombs in time. Bart shares a kiss with Avery and returns to 2049 with Nora, where Jay and Joan are both alive. In the present after Team Flash leaves for brunch, Iris' hairbrush disappears in a green light.

Kramer is frustrated by how Flash drops off criminals without context. Joe suggests that Kramer have a line to Flash, but Barry is hesitant. That night, Goldface leads a gas attack on CCPD in search of bullets that can remove metahuman abilities, knocking out Barry and Kramer. They awaken with explosive meta-dampening cuffs, though Kramer's mimic abilities are able to short-circuit them. Despite her inability to control her powers, Barry inspires her to mimic Goldface's abilities to stall him while he defeats his crew as Flash. Later, Barry reveals his identity to her, though she has already deduced it and agrees to train and communicate with her. Meanwhile, Caitlin and her date Dr. Marcus Ficus are interrupted by Frost and Mark. Caitlin angrily expresses her distrust for Mark, though Mark helps her realize that she was afraid to commit to Marcus and instead focused on her hatred. Caitlin apologizes to Frost and Mark. Meanwhile, objects in Joe's house begin disappearing before Iris. She seemingly loses time, and her eyes flash green.

The recently-paroled Jaco Birch is arrested for the incineration of O'Shaugnessy's manager Stan Mullen who he was arguing with a night prior. He professes his innocence and his desire to be there for his son Harold. With there being no hard evidence against Jaco and with it being Henry Allen's birthday, Barry tries to convince his team of Jaco's innocence. Flash and Frost find bartender Donna Winters incinerated, but Chester discovers that the methods of burning do not match Jaco's abilities. Flash and Frost stop Jaco from kidnapping Harold from social services, and they work together to stop a lava channel from erupting. At CCC Media, Iris has Allegra interview social media influencer Rosie Levin with her constituent Taylor Downs, but Allegra shirks the interview to pursue a story involving ex-con Lydia Sanchez. Iris publishes both stories and has Allegra apologize to Taylor, but she refuses to listen. That night, Jaco and Harold reunite while Joe's family celebrates Henry's birthday. Later, Team Flash focuses their efforts on finding the real killer.

Deon visits Iris to treat her for her "time sickness", though he is unsure of what it is or how she contracted it. Barry and Chester discover another incineration and contain a mysterious "Black Flame" from it. Chester has a nightmare of it breaking out. The Black Flame does so and he fears that it's the ghost of his father Quincy. It manifests as him and strikes again; Cecile realizes that it's feeding off of Chester's grief. Chester rejects the entity and it disappears. Joe returns and states that the incinerated victims were dealing with grief, and the team deduces that the Black Flame is a sentient entity trying to survive. Meanwhile, Iris and Sue Dearbon travel to Coast City to investigate the Coast City Phantom, who they identify as Tinya Wazzo. While searching for her, Iris opens up to Sue about her time sickness. They find Tinya at her missing adoptive mother's home. She has also been searching for her birth mother, who abandoned her, and Iris convinces her to come with her and Sue. That night, Deon visits Iris with bad news.

Deon tells Barry and Iris that she is causing time to fracture around her. After Frost is attacked by the Black Flame, she and Carla Tannhauser enact a plan to amplify Frost's cryokinetic abilities to draw it out and trap it in a fusion sphere, but fail and Frost is injured. Caitlin is upset that Carla would use Frost as bait, but Carla reveals that she will soon develop cryokinetic abilities, and that the plan will work if she and Frost draw out the Black Flame together. However, the sphere's structural integrity is compromised and Carla goes into cardiac arrest, so Frost pulls her out and the Black Flame escapes. Team Flash comes together later to revamp the plan. In Coast City, Iris and Sue bring Tinya to an adoption agency to find her mother. The receptionist leaves and returns to find the entire room completely empty. Tinya finds her mother Renee and they talk, but Iris's eyes flash green and Renee vanishes in a green light. Meanwhile, the Black Flame appears to Caitlin and speaks to her using Ronnie Raymond's voice.

Ronnie begs Caitlin to save him. At S.T.A.R. Labs, she recognizes each of the Black Flame victims and realizes it has been searching for her. Despite Barry's suspicions that the Black Flame is manipulating her, she and Chester devise a plan to rescue him. She also tells Marcus who then breaks up with her. Ronnie contacts Cecile and begs her to set him free. She feels his agony and proposes to Team Flash that they put him out of his misery. The Black Flame then goes to where Ronnie and Caitlin proposed to one another, and Flash tries to trap him in the fusion sphere. Caitlin and Frost arrive and destroy it, and Cailtin uses a quantum splicer on the Black Flame; Ronnie is freed and he faints. Meanwhile, Allegra worries that Chester's openly-sourced technology will fall into the wrong hands. In Coast City, Tinya angrily causes Iris to disappear. Sue goes back to Central City and tells Barry. That night, Ronnie awakens and reveals to Caitlin that he is not the real Ronnie and transforms into Deathstorm.

Flash rescues Caitlin from Deathstorm, who escapes and continues incinerating grieving people, so Kramer mobilizes the CCPD. Cecile connects to S.T.A.R. Labs' search systems to track Deathstorm, but he possesses her and demands Caitlin. After having a manifestation of Esperanza Garcia fight Allegra, Deathstorm kidnaps Caitlin and announces his intention to make her his bride, but lets her go stating that she isn't ready. Team Flash deduces that Ronnie's grief was transported away by the singularity and that it's been traveling through space for the past seven years. Chester plans to modify the Mental Augmentation Chamber (MAC) in order to emit cosmic energy that can harm Deathstorm and Frost volunteers to harness it. Meanwhile, Iris inexplicably returns as her time sickness pulled her into the Still Force and saved her. However, it infects Deon, preventing him from seeing Iris's future and he inexplicably vanishes. Sue is able to stop Iris from doing the same. That night, Eddie Thawne appears in her apartment.

The ghost of Eddie (conjured by Deathstorm) attempts to goad Iris into grieving his death, but she resists. Sue wakes up, and together they manage to contact Joe for help, but fail to escape. At S.T.A.R. Labs, Caitlin's condition worsens, though Frost, Barry, and Chester have almost completed the MAC. Deathstorm attacks S.T.A.R. Labs, and sends ghosts of Team Flash's past to haunt them and feed off their grief, fueling Caitlin's transformation. Deathstorm tells Frost that she has no grief or real emotions, as she is a copy of Caitlin and made only for protecting her. Mark arrives at S.T.A.R. Labs to help, and with some of Caitlin's grief, is able to help Frost transform into Hellfrost. They lure Deathstorm, and Hellfrost manages to defeat Deathstorm and absorb his grief, but at the cost of her own life.

Team Flash struggles to adjust to Frost's absence. Allegra and Cecile join Flash in the field to stop Blockbuster, a bank robber who stole a powerful exosuit from Ivo Labs, but fail to detain him and he flees with untraceable cloaking technology. Iris struggles with writing Frost's obituary, though she is able to collect stories from the public about Frost's positive impact. While Chester and Allegra argue over the right way to honor Frost, Mark gets immensely drunk at O'Shaughnessy's. Barry completes every item on Frost's bucket list. After being convinced by Barry to go to the funeral, Caitlin realizes that Frost's voice lives on in her. Caitlin brings Mark to her apartment and resolves to bring back Frost. That night after discussing Flash's new allies in the field with Taylor at CCC Media following Blockbuster's defeat, Iris vanishes in a green light.

Barry awakens to find Iris missing and goes to Tinya for help, but to no avail. Deon returns and states that Iris is lost in the Still Force. Against Joe's advice, Barry follows him in with an isotopic sensor that can help locate Iris. They find Renee, but she vanishes again. Deon then finds a temporal particle in place of Iris, but he steals it, destroys the sensor, and escapes. Barry gets trapped in a facsimile of Joe's house with Nora, who Deon dragged in from 2049. Eventually, Barry is able to connect to the Still Force and he and Nora are able to smash through the temporal barriers blocking their exit and escape. Meanwhile, Kramer brings in Chester to analyze a device found after an explosion. He discovers that it was built using his openly-sourced technology, but later learns it was in an attempt to provide hot water to citizens in need. Later, someone hacks into Chester's computer and downloads all of his files. Though initially reluctant, Mark agrees to help Caitlin bring back Frost.

David Singh asks Barry to locate a gamma absorption array stolen from Mercury Labs. He finds the thief, Pytor Orloff, but is blasted by the array, causing him to age 30 years. The more Barry uses his speed, the faster he’ll age. He struggles to catch Orloff while suffering from body pain and memory loss. He and Cecile find a laptop with his work, and Chester deduces that Orloff’s plan is to become immortal by stealing energy from everyone in Central City, aging them hundreds of years. He activates his machine, though Barry is able to force the gamma field backwards, inverting the energy charge and reverting the changes to Orloff and Barry. Barry is de-aged to 29 years old and Orloff is sent to prison. One week later, Barry goes to Caitlin's apartment and learns about her plan to restore Frost. She refuses to accept that Frost is gone, so Barry wrecks her equipment.

A new speedster stops a fire at Ivo Labs, but also steals a Newton Battery. Fearing it could be Thawne, Barry checks on him on Lian Yu. Thawne is aware of Frost's death and deduces that the speedster started the fire by accident. Meanwhile, Lydia informs Allegra about hostility from their former gang, the Arañas, now led by Kimiyo Hoshi and Millie Rawlins. They attack CCC Media during an interview, so Chester activates a forcefield. Taylor exposes Allegra as a former member of the Arañas to her employees, so Allegra reveals herself as the light-based meta assisting Flash to regain their trust. Allegra holds Hoshi and Rawlins off while Lydia exposes the Arañas live, prompting them to flee. Taylor reconciles with Allegra, but also tells her that she can’t hide from the world. Caitlin tells Team Flash that she needs to step back to figure things out. That night, Flash catches a Ninja Speedster returning the Newton Battery. The Ninja Speedster is revealed as its inventor and the CEO of Fast Track Labs, Meena Dhawan. Flash agrees to mentor her.

After training Meena, Barry is shown the Biometric Lightning Oscillation Chamber (BLOC), which grants her speed. She introduces him to its co-inventor: Thawne, with his original face, though he doesn't remember his past or Barry. On Lian Yu, the imprisoned Thawne theorizes that the other is from another timeline. Barry tries to stop Meena from using the BLOC, but she connects to the Negative Speed Force and begins draining power junctions. The alternate Thawne states that he fell in love with Meena and had visions of the BLOC, but was unaware of the NSF. He and Team Flash find Meena in Keystone City, and he is able to disconnect Meena from the NSF. Later, Ray Palmer informs Team Flash that the Flashpoint Thawne was revived by the Time Wraiths[N 2] and Barry theorizes that he was revived again and brought to Meena. Meanwhile, Cecile's powers grow when she stops a bank robbery and mugging, unaware she is stalked by a mysterious woman. Mark contacts Caitlin with a new plan to revive Frost. John Diggle approaches Thawne on Lian Yu for help in opening his box, but it disappears when Diggle chooses to remain with his family instead of accepting its power. Deon visits the imprisoned Thawne and tells him that it's time to "fulfill his destiny".

Flash reveals his identity to Meena and gives her the moniker Fast Track. Deon kills the imprisoned Thawne and attacks Meena and Flashpoint Thawne alongside Negative Force counterparts of Alexa Rivera and Bashir Malik. Iris reappears in 2049 and Joan Williams informs Bart and Nora that Iris's body is flooded with negative tachyons, preventing her from returning to 2022. Nora travels there to inform Team Flash and they realize that the Negative Forces infected Iris knowing that she would infect the Positive Forces. Meanwhile, Mark has Caitlin enter the Consciousness Resurrection Chamber (CRC). Cecile realizes that she stole Rosalind Dillon's powers so Joe brings them both to Iron Heights so Cecile can test her powers against Mona Taylor, but she ends up stealing her powers as well. Later, Barry helps Meena share her speed with Flashpoint Thawne and they fight the Negative Forces. Negative Deon summons Iris and uses her to shield himself from Flash's attacks, killing her. The dead Thawne is resurrected in Eobard's body.

The Negative Forces transform Thawne into their new avatar. In the Negative Speed Force, they explain to Barry that this is their revenge for when he weakened them by removing Thawne's speed. Barry, Meena, Bart, and Nora fight Thawne in Central City, but he sends the latter three back in time. Meanwhile, Cecile rescues Bashir and transfers her powers to him which he uses to rescue the other Forces so they can aid Barry. Iris is saved by the Time Stone and Damien Darhk helps her resurrect herself. Jay Garrick reunites her with Barry. With help from the Forces, he reverses a powerful attack from Thawne back into him, destroying him and removing him from the timeline. After the universe "resets", Iris is cured of her time sickness and the speedsters return to their native time. The BLOC is depowered and Meena loses her speed. The CRC malfunctions and Mark encounters a new Frost claiming to be "a friend". Mona and Dillon's powers are restored while Cecile develops telekinesis. Tinya and Renee are reunited. Iris mentions that the NSF will find a new avatar and Barry states that he'll be ready. A blue crystal is shown at a laboratory in 2049.

One week after Eobard Thawne's defeat, Barry Allen creates a "map book" noting future events, including his promotion to director of the Central City Police Department (CCPD) CSI Division from Kristen Kramer, Cat Grant offering to buy Central City Citizen Media from Iris West-Allen and his fight against Owen Mercer / Captain Boomerang. The battery for the Roemer Accelerator that Mercer was stealing explodes, trapping Barry and Iris in a time loop, and they argue about their future. Joe West and Cecile Horton tell Barry that the future is something you create, not follow, prompting him to burn the book. On the final loop, Barry phases with the accelerator, nullifying a nuclear blast while Chester P. Runk and Allegra Garcia share a kiss. Barry and Iris accept their offers, with the latter acquiring the Coast City Gazette. Joe and Cecile talk about leaving Central City. Barry finds that "Caitlin Snow" is now neither Caitlin nor Frost. Mercer delivers the power source to a speedster with a bat-like emblem.

"Caitlin" introduces herself as Snow, a blank slate resulting from the Consciousness Resurrection Chamber (CRC)'s malfunction. Mark Blaine has Team Flash try to reverse the process but secretly tries to restore Frost as well, resulting in another malfunction. They learn restoring both Caitlin and Frost is impossible and vote on who to restore, but ultimately decide to let Snow choose. Meanwhile, Hartley Rathaway is attacked by a new Fiddler and goes to S.T.A.R. Labs for help. After talking with Snow, he tries to kill the Fiddler, but Flash convinces him not to, and they rescue his boyfriend Roderick and their crew from a vibrational phase. Mercer steals Hartley's sonic gauntlets and retreats with the Fiddler, who Team Flash identifies as Andrea Wozzeck. Snow chooses to live her own life as Khione. Hartley wrecks the CRC, enraging Mark, who vows to get revenge. The speedster uses the sonic gauntlets to stabilize into a physical form before planning to make Central City pay for Barry's actions.

The Rogues (Mercer, Wozzeck, and Michelle Amar / Murmur) steal a temporal scanner from Corbin Taft Industries. Barry realizes that they're building a Cosmic Treadmill and are missing a vibration engine. He assembles Hartley, Mark, Jaco Birch, and Goldface to steal it before the Rogues can, but they decide to do the mission without him until Barry can prove his trust in them. He does so, but Mark betrays the group and reveals his allegiance to the Rogues in exchange for Frost's resurrection. The Rogues intercept Barry's group while the speedster temporarily disables his speed and escapes with the engine. Meanwhile, Khione tries to convince Allegra to stop avoiding Chester. Iris worries that the speedster is the new avatar for the Negative Speed Force. Hartley, Jaco, and Goldface agree to continue assisting Team Flash. Chester informs Team Flash that the Rogues' equipment are Wayne Enterprises designs and that Ryan Wilder / Batwoman has gone missing. The speedster unmasks herself to the Rogues as Ryan.

Roy Bivolo and the speedster (now calling herself the Red Death) capture Barry and cause a citywide blackout. While imprisoned, Barry learns that Red Death's speed is artificial and tells Mark that it isn't too late to come back from his mistakes. Ryan goes to Iris, but Iris realizes that she is Red Death. Ryan reveals that she is from an alternate timeline where she and Flash became enemies.[a] After being rejected from the Speed Force, she landed in Iris's timeline and wants to use the Cosmic Treadmill to return home and use Iris as bait for her timeline's Flash. Red Death brings Iris to her hideout and threatens her life in order to coerce Barry into powering the treadmill, causing a lightning storm. Mark sabotages the treadmill and is overwhelmed by the Rogues while Team Flash evacuates Barry and Iris. Meanwhile, after seeing Cecile use her powers to rescue Jenna from the storm, Joe agrees to remain in Central City. Chester and Allegra agree to talk as soon as Red Death is defeated. Red Death vows to bring war to Flash.

The Rogues attack CCPD and capture Kramer. While rescuing Mark, Barry is attacked by Red Death, who drains his speed and creates psychic extensions of herself around the world with help from Gorilla Grodd. Khione learns that she can still help Team Flash without powers and wakes Mark with a kiss. After talking with Joe, Barry goes to Grodd, who joined Red Death because he felt abandoned after finding that the gorillas of Gorilla City had lost their sentience and were scattered following the Crisis. After Barry agrees to help Grodd restore his community, Grodd restores Barry's speed and dispels Red Death's doubles. With help from Hartley's group and the main timeline's Batwoman, Barry defeats Red Death and has her remanded to A.R.G.U.S. custody. Two weeks later, Joe moves to the countryside with Jenna. At his farewell party, Chester and Allegra begin dating and Khione announces Iris's pregnancy, which wasn't supposed to begin for another three months.

Rebecca Sharpe, who is alive on Earth-Prime, is framed for attacking her fiancé Dominic Stewart. Cecile and Allegra work to prove her innocence, but Rebecca is kidnapped by people with dark matter refractors that deflect Allegra's and Cecile's abilities. Cecile also misses her train to Joe's and worries about being far from Jenna, but Allegra consoles her. They realize that Dominic's brother Tony embedded a refractor in Rebecca's engagement ring in order to reverse her luck ability and extort her job as a dealer in order to pay off his gambling debts. Cecile telekinetically removes Rebecca's ring, destroying the refractor while leaving Tony for Kramer. Meanwhile, Mark is convinced that Khione has powers, believing that they're what woke him and that they're all that's left of Frost. Khione tells him that Frost lives on in his memories and conjures a snowfall. The next morning, Dominic wakes, Cecile invites Allegra to move into Joe's house, and Team Flash has a baby shower. Chester reveals that Khione is not a human or a metahuman.

Nia Nal has been searching for an ancient source of Naltorian dream energy. She loses her powers to a hooded robed figure while in a nightmare involving Iris and goes to Central City for help. Iris realizes that her article on the Red Death is the Pulitzer-winning article from the map book, and questions if she's following destiny instead of making her own choices. After Nia and Iris get pulled into a dream, Nia helps Iris realize that destiny is not one choice, but the result of a lifetime of several choices. Iris helps Nia realize that to increase her potential, she needs to, paradoxically, give up control. After doing so, Nia meets the spirit of the first Naltorian with dream abilities, who promises to teach her. They wake, and Iris publishes her article. Meanwhile, Mark takes Khione out to do activities that he did with Frost, ignoring all of Khione's ideas. She realizes that Mark still only sees her as Frost and leaves. Later, Mark apologizes to Khione and decides to leave Central City, causing Khione to inadvertently freeze Cecile's banquet out of sadness.

Barry, Iris, and a group of D.O.E. agents inspecting S.T.A.R. Labs get trapped in the speed lab. When Barry notes that a "time magnet" will be stored in the Flash Museum in 2123, the group deduces that one of them must have stolen the magnet from the future without its stabilizer, trapping them in the same moment. As one of the agents is replaced by a statue, the group realizes that exposure to the time magnet will eventually kill them. Barry and Iris realize that Inspector Tao knows nothing about her job and expose her as the thief. She reveals herself as Lady Chronos. Barry charges her belt so she can reunite the magnet with its stabilizer in 2123 and convinces her to let herself be arrested instead of dying. The timeline resets, freeing Barry and Iris and restoring the agents with no memories of the events. Meanwhile, Khione meets with Carla Tannhauser off-screen. After Chester tells Allegra that he loves her, she worries about her future with him. Cecile convinces her that their relationship is not doomed and she later admits her love to Chester.

Team Flash has a surprise birthday party for Barry with John Diggle and Wally West in attendance. While there, Wally talks about projecting his consciousness into other timelines. Ramsey Rosso arrives and knocks out the guests. He makes Barry feel guilty for getting extra years to live while his friends die and explains to Wally that the timelines are alternate Earths of a reborn multiverse. He takes over Wally's mind and has him kill Barry. Barry awakens in purgatory with Oliver Queen, whom after the Crisis has lived on as the Spectre, watching over and protecting the new multiverse. Oliver helps him accept the guilt he feels and resurrects Barry by punching in the face while temporarily returning with him as Green Arrow. Wally opens a gateway into the multiverse, allowing Rosso to spread his infection. Barry helps Wally break Rosso's influence and Khione restores Diggle, who joins the others in holding off Rosso. This allows Oliver to get a clear shot into the gateway and purge the multiverse of Rosso's infection, which restores everyone. Oliver depowers Rosso and cures his HLH. Afterwards, Oliver explains that Khione is connected to the natural world and says goodbye to Diggle and Barry.

Chester gives Allegra her first suit and Iris receives a Pulitzer nomination. Barry gets transported to the day Nora Allen dies. He goes to Joe for help and later sees his parents, but is knocked unconscious by Eobard Thawne. While investigating, Joe finds a blue crystal and becomes possessed. After being hospitalized and having lunch with his parents, Barry is approached by Thawne, who gloats about him being unable to stop his plan to kill Barry's younger self. Barry returns to the hospital and says goodbye to his parents. The possessed Joe then attacks him, stating that he is not the new Negative Speed Force avatar but still wants to correct the imbalance Barry's legacy leaves on the timeline. Barry frees Joe and returns him to his car, but the crystal disappears. Barry then participates in the fight in which Thawne kills Nora, warning his earlier self not to interfere. Afterwards, Barry tells Thawne that he has made peace with Nora's death before he is transported away again and Thawne loses his powers. Elsewhere, a man resembling Eddie Thawne is struck by lightning at Mercury Labs, finds a file about Eddie's death, and wonders who he is.

Chester finds traces of cobalt where Barry was taken. Mark returns, but he attacks members of Team Flash and is later shown to be possessed by the crystal. After he gasses CCC Media, Khione rescues Taylor and Aariz by growing plant cells in their bodies, but their skin turns green. They flee in horror, and Mark calls Khione an abomination. The Speed Force defends Iris from Mark and explains that he became a vessel for the Negative Speed Force. After the Speed Force convinces her to embrace her power, Khione frees Mark by disintegrating and reassembling his body, but the crystal disappears. Barry returns as Iris goes into labor but is pulled away again and Khione makes plans to leave Central City. Elsewhere, Malcolm Gilmore— Eddie's facsimile— goes to Captain Daisy Korber at the CCPD to learn about Eddie. After hearing a voice telling him to find Iris and seeing Eddie's memories, he breaks into CCC Media and digs up Eddie's grave, only to find it empty. He realizes that he is Eddie and pulls out the bullet he shot himself with.

The Speed Force warns Team Flash that Barry and the crystal are in 2049 before vanishing. Eddie watches Korber get pulled into a singularity that opens over his grave. At the Flash Museum, he sees a girl resembling Nora West-Allen claiming to be his daughter, but the real Nora stops him. Team Flash 2049 finds that Eddie is subconsciously opening the singularities. Nora becomes possessed by the crystal and tries to tempt Eddie into accepting its power, but Barry appears and escapes with him. Eddie is angered by how his sacrifice didn't erase the Reverse-Flash and how he was forgotten while Barry lived and married Iris. In 2023, Cecile projects her consciousness into her 2049 self, but returns when she learns that she rarely visits Joe due to work. After Chester (at Khione's urging) consoles her, she returns and frees Nora from the crystal's influence. Eddie asks 2049 Iris to be with him again, but she rejects him. As the Negative Speed Force begins to fracture the timeline, 2049 Iris talks with Barry before he is pulled away again. Now in possession of the crystal, Eddie accepts its power and opens a portal.

Now a speedster known as Cobalt Blue, Eddie resurrects Eobard Thawne, Hunter Zolomon / Zoom, Savitar, and August Heart / Godspeed and gathers them in the Negative Speed Force. In 2023, they fight Team Flash and Nora. Cecile adopts her future costume and codename Virtue, Allegra saves Chester from Eobard, and Jay Garrick steals Eddie's speed. Eddie retreats into the Negative Speed Force to gain more speed. Not wanting Eddie to die, Barry follows him in and convinces him not to become like Eobard and that they can create a better world by coexisting. Eddie destroys the crystal and says he is happy for Iris and Barry returns to her at the hospital. Mark reveals that Chester is a metahuman with black hole powers. The next morning, Nora is born and Harrison Wells tells Khione to ascend as the natural order's protector. She bids farewell to Team Flash and returns her body to Caitlin. At a celebration one week later, Barry apologizes to Caitlin for how they left things and Joe and Cecile get engaged. Barry unleashes a lightning bolt and chooses Avery Ho, Max Mercury, and Jess Chambers to become new speedsters, while continuing to be The Flash.