Eliza comes to town to celebrate Thanksgiving with her daughters. Alex decides it’s time to come out to her mother; Kara is shocked when Eliza suggests Mon-El has feelings for her, and Winn and James consider telling Kara the truth about the Guardian... (more). Meanwhile, CADMUS unleashes a virus that instantly kills any alien in the vicinity so Kara enlists an unexpected ally – Lena Luthor. Barry Allen and Cisco Ramon seek Kara’s help with an alien invasion on their Earth. The crossover continues on The Flash S03E08, Arrow S05E08, and DC's Legends of Tomorrow S02E07.

Brenda Strong, Carlos Valdés, Grant Gustin, Helen Slater, Katie McGrath, Robert Gant