Supergirl realizes that in order to stop Lex and Leviathan she must work with the one person she never thought she'd trust again - Lena. Nia keeps dreaming about Brainy but struggles with what the dreams are trying to tell her. Meanwhile, Brainy realizes there is only one way to stop Lex.

Supergirl and the team go head to head against Rama Khan and Leviathan. Meanwhile, Lena and Lex must join forces when Project Non Nocere fails, leaving the two siblings in serious danger.

Lex proceeds to lay an intricate plan to bring Lena closer to him, defeat Leviathan's latest attack, and pit Supergirl against Leviathan; how Lex came into power after Crisis is revealed.

Alex uses a pair of Obsidian contact lenses to visit a virtual National City where she takes on a whole new persona. Meanwhile, Kelly helps William investigate Lex. Kara deals with difficult news.

Nia's roommate, Yvette, is attacked by a man targeting Dreamer because he doesn't like that Dreamer is transgender and wants her to quit being a superhero. Determined to protect her community from additional harm, Dreamer refuses to give into his threats and puts herself in the line of fire to stop him. Supergirl stands by Dreamer and enlists additional help from Brainy. Meanwhile, Alex, J'onn and Kelly attempt to rescue a man stuck inside a virtual reality escape room.

Lex tasks Supergirl with protecting Andrea from an anti-tech extremist, but his nefarious purpose goes beyond merely keeping Andrea alive. Meanwhile, Lena moves forward with Non Nocere, with Lex's help.

Mxyzptlk returns with a proposition for Kara – what if she could go back in time and tell Lena her secret before Lex did, would things turn out different? Looking back over key moments throughout the series, Kara must decide if she wants to change history to become friends with Lena again.

Supergirl helps Winn face his greatest fear. After Alex sets out to find evidence against Lex, Brainy must decide between helping his friend or continuing to secretly work for Lex.

As Supergirl tries to thwart a Toyman copycat, Winn Schott returns from the future.

The subsequent complications from the Crisis leave Supergirl to face a chaotic threat.

Harbinger gathers the greatest heroes of several worlds to battle the Anti-Monitor, his shadow demons, and the anti-matter wave that is sweeping across the multi-verse. While Lois, Brainiac-5, and White Canary search for Kal and Lois' missing son Jonathan, Alex asks for Lena's help evacuating Earth-38's population before it's too late.

Alex is torn between destroying Lena before she can unleash Myriad, or using Malefic to stop the Luthor's mind-control plan. Meanwhile, Khan prepares to wipe humanity from the planet.

Leviathan's leader comes after Lena to get the medallion, and Lena convinces Supergirl to take her to the Fortress to find a weapon capable of stopping him. Kelly makes a confession to Alex, and John reaches out to his brother.

The connection between Lena and Andrea is explored via flashback, as Lena attempts to redeem her stepbrother's legacy. In the present, Leviathan launches an attack on the DEO to eliminate Rip Roar.

On the eve of the worldwide launch of Andrea Rojas's VR contact lenses, Kara and William team up on an investigation that exposes a terrorist plot. Kelly and Alex celebrate an anniversary, but Alex's safety is in jeopardy.

Kara continues to investigate what William is up to, while Malefic launches an attack on John's friends through Alex. James and Kelly return to their hometown and discover corruption... and no one willing to stand up to it.

Kara meets with Lena for the first time since she admitted her secret identity to her. J'onn recruits Nia to help him dwell further into his memories, and Nia deals with her relationship with Querl. An old friend visits Kelly and asks for help with his memories, but he isn't what he seems.

John tells the others about Malefic's attack on him, and discovers that some of his memories have been erased. While Kelly helps John determine the extent of the psychic attack, Supergirl, Alex, and Querl search for Malefic. Meanwhile, Andrea demands more from Kara at work, and Lena questions Eve's loyalties.

Kara prepares to accept a Pulitzer for her writing, and comes to a decision about sharing her secret identity with Lena. A new villainess and former foe emerges from the Phantom Zone to fight John, and Lena sells CatCo to an associate who has big changes in store for the organization.