Supergirl makes a new ally. Lena and Lex battle for control of Luthor Corp.

Nia and Brainy attempt to save Supergirl from the Phantom Zone by time traveling back to Kara's home in 2009. While determined to secure the item needed to help Supergirl, Brainy is worried about keeping a low profile so as not to alter the future timeline. However, when their ship crashes upon arrival, a young Kara Danvers is the first on the scene. Meanwhile, a young reporter named Cat Grant sets her sights on Midvale as she suspects there is a big story in the small town.

As the Super Friends brave the Phantom Zone to bring Supergirl home, each member of the team is confronted by visions of their worst fear.

Kelly meets Joey, a young orphaned alien boy, who is acting out in foster care because he fears there is something wrong with his brother Orlando, who is incarcerated. Kelly asks Kara to help her investigate and they stumble upon abuse at the prison. Meanwhile, Nyxly crashes one of Nia's dreams and asks her for help.

Supergirl and team must stop Nyxly from vanquishing a familiar face from Supergirl's past - Mr. Mxyzptlk. Mxy returns and explains Nyxly's dark history to the super team in the best way he knows how - in song form. Meanwhile, Lena visits her mother's birthplace in Newfoundland, eager to dig into her past but is shocked by the small town's icy reception towards her.

Supergirl and team race Nyxly for control of a magical totem that controls courage. Supergirl and Nyxly battle and each get a piece of the totem but learn the first person to pass the test of courage will gain control of the entire thing. Meanwhile, Lena is still struggling to make sense of her newfound gift.

Supergirl continues to fight Nyxly for the remaining totems but after Nyxly kidnaps William, Supergirl realizes she needs to take a more proactive stance to keep National City safe. Meanwhile, Alex faces the biggest challenge of her life.

Supergirl is determined to keep everyone safe from Lex and Nyxly so she doubles down on patrol, especially as Alex and Kelly's bachelorette party is coming up. Alex is torn between duty and finally allowing herself the time to enjoy her new family. Brainy receives heartbreaking news, and William clashes with Andrea over her recent coverage of Lex.

Supergirl is joined by familiar faces from the past to help her stop Lex and Nyxly for good. Meanwhile, Alex and Kelly prepare to walk down the aisle.