After losing Mon-El, Kara decides to give up her human life and dedicate herself full-time to being Supergirl. Meanwhile, a new menace threatens National City, and real estate mogul Morgan Edge makes a bid to buy up CatCo. Also, Alex confesses a secret to Maggie, a citizen of National City has a mysterious connection to Kara, and Lena makes a bold move.

Supergirl goes with Hank to Mars in response to M'gann's telepathic request for help. Meanwhile, Maggie invites her estranged father Oscar to her and Alex's wedding shower that's sponsored by Eliza.