Kara is surprised to find that CatCo has a new owner who has brought in a star reporter; new couples emerge and explore their budding relationships; J'onn J'onzz receives an unexpected visitor.
Supergirl, Alex and Brainiac thwart an alien attack while William investigates Kara; J'onn J'onzz and Kelly use Obsidian tech to solve a problem.
Kara tries to mend her relationship with Lena; J'onn J'onzz goes deep into his memories; Kelly tries to help an old friend.
Kara's investigation into William Dey's "criminal" activities results in the shocking revelation he is not who she thinks; the conflict between Malefic and J'onn J'onzz reaches a boiling point.
On the eve of the worldwide launch of Andrea Rojas's virtual reality 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.
While a new villain is under arrest at the D.E.O., Supergirl uses him to find information on who is responsible for the recent attacks; Andrea and Lena think back on their tumultuous past.
Supergirl finally learns the truth about Lena while tangling with Leviathan; J'onn J'onnz makes a discovery about his brother's whereabouts.
Supergirl's struggle against Leviathan reaches a boiling point as she faces off against Rama Khan; as Lena and Hope work to launch Project Non Nocere, Hope proves to be an invaluable asset to Lena.
The Monitor sends Harbinger to gather the worlds' greatest heroes -- Supergirl, The Flash, Green Arrow, Batwoman, White Canary, The Atom and Superman -- in preparation for the impending Crisis; Lena must find a way to save the people of Earth-38.
The subsequent complications from the Crisis leave Supergirl to face a chaotic threat.
Supergirl tries to thwart a Toyman copycat; Winn Schott returns from the future.
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.
Mxyzptlk returns with a proposition for Kara; Kara must decide if she wants to change history to become friends with Lena again.
Lex tasks Supergirl with protecting Andrea from an anti-tech extremist; Lena moves forward with Non Nocere, with Lex's help.
Nia's roommate is attacked by a man targeting Dreamer; Dreamer refuses to give into the man's threats and puts herself in the line of fire to stop him; Alex, J'onn and Kelly attempt to rescue a man stuck inside a virtual reality escape room.
Alex uses a pair of obsidian contact lenses to visit a virtual National City where she takes on a whole new persona; Kelly helps William investigate Lex; Kara deals with difficult news.
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.
Supergirl and the team go head-to-head against Rama Khan and Leviathan; Lena and Lex must join forces when Project Non Nocere fails, leaving the two siblings in serious danger.