Supergirl is stunned to learn that a part of Krypton survived. Alex is attacked while out with Ruby, and Lena considers how far she will go to keep Reign contained.
Kara investigates a new group that has a mysterious connection to Supergirl, while Samantha feels like she's letting Ruby down. Later, J'onn confesses an old secret.
Kara investigates when an alien ship crash lands deep underwater beneath National City. Hank attempts to bond with his father. Samantha looks to her estranged mother for answers.
Supergirl teams up with Saturn Girl, Livewire and Psi to recover a prisoner who has information on how to defeat Reign.
When Reign starts hunting Ruby, Supergirl and Alex work together to keep her safe. Supergirl and J'onn look to Sam's mother for advice on how to stop Reign.