Storyline: With Professor Pyg striking fear throughout Gotham, Gordon and Bullock head into the Narrows to look for clues. Bruce Wayne meets a former friend, Grace, who convinces him to come along for a night out with some old classmates. Meanwhile, Sofia's relationships with Penguin and Gordon continue to evolve.
Storyline: Kara investigates when an alien ship lands deep underwater beneath National City; Hank attempts to bond with his father; Samantha looks to her estranged mother for answers.
Storyline: Kara and Alex head home to Midvale for a little R&R. While there, Kara recalls a painful memory of a childhood friend's death and how that traumatic experience brought the Danvers sisters closer together.
Storyline: When multiple children get sick from lead poisoning, Morgan Edge points the finger at Lena and blames her creation of the lead bomb she made to save National City from the Daxamites. While Lena knows she never intended any harm, she fears there may have been a flaw in her design, leaving her responsible. Kara teams up with Samantha to clear Lena's name, but it turns out to be harder than they thought. Meanwhile, Alex and Maggie make a crucial decision about the future of their relationship.
Storyline: Kara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl. Meanwhile, Samantha feels like she's letting Ruby down.
Storyline: Maggie reaches out to her estranged father when Eliza throws her and Alex a wedding shower, while Supergirl joins J'onn on a personal mission.
Storyline: Psi, a thief with psychic powers, attacks National City. Able to immobilize people by tapping into their worst fears, Psi proves a formidable opponent for Supergirl. Meanwhile, James and Lena are at an impasse, and Samantha starts her new job at L-Corp.