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.
Supergirl and the super friends take drastic action after a loved one is kidnapped by Nyxly and Lex. An unlikely ally steps in to help the team.
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.
When Lex Luthor appears by Nyxly's side, Supergirl and team must deal with the emotional fallout of facing their two biggest foes at the same time. Alex makes plans for the perfect proposal to Kelly, but work keeps getting in the way.
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.
As Supergirl and Zor-El make their return to National City, they are determined to keep the Phantom Zone behind them and enjoy being superheroes together. Unfortunately, their overzealous efforts backfire, creating a whole new threat to National City.
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.
Part two of the flashback episodes pick up where things left off - Young Kara experiences kryptonite for the first time, Nia and Brainy are trapped by invading aliens, and a young Cat Grant may be the reason Supergirl never gets out of the Phantom Zone.
Supergirl makes a new ally. Lena and Lex battle for control of Luthor Corp.
As the stakes with Lex are raised higher than ever before, Lena must decide how far she is willing to go to stop her brother. Meanwhile, Supergirl and the team are faced with a challenge unlike anything they've ever dealt with before and it brings Alex to her breaking point.
Twenty-four-year-old Kara Zor-El, who was taken in by the Danvers family when she was 13 after being sent away from Krypton, must learn to embrace her powers after previously hiding them. The Danvers teach her to be careful with her powers, until she has to reveal them during an unexpected disaster, setting her on her journey of heroism.