The November 28 episode of "Supergirl," titled "Medusa," will serve as a lead-in to The CW crossover event "Invasion!" which sees the Arrowverse come together to take on the invading alien threat of the Dominators, and new images reveal how Kara Danvers is recruited into the superhero team-up.
While "Medusa" is not fully a part of the larger crossover story, images show Barry Allen and Cisco Ramon visiting Kara's Earth to ask for her help in fighting the Dominators. Other images introduce Kara and Alex's mother, Eliza, inspecting a sickly-looking Mon-El, and Hank Henshaw/Martian Manhunter having a serious conversation with Supergirl.
A NIGHT OF CONFESSIONS; THE EPIC SUPERHERO CROSSOVER KICKS OFF TONIGHT — Eliza (guest star Helen Slater) comes to town to celebrate Thanksgiving with her daughters. Alex (Chyler Leigh) decides it’s time to come out to her mother; Kara (Melisa Benoist) is shocked when Eliza suggests Mon-El (Chris Wood) has feelings for her, and Winn (Jeremy Jordan) and James (Mehcad Brooks) consider telling Kara the truth about the Guardian. Meanwhile, CADMUS unleashes a virus that instantly kills any alien in the vicinity so Kara enlists an unexpected ally – Lena Luthor (Katie McGrath). The epic superhero crossover kicks off tonight when Barry Allen (guest star Grant Gustin) and Cisco Ramon (guest star Carlos Valdes) seek Kara’s help with an alien invasion on their Earth. Stefan Pleszczynski directed the episode written by Jessica Queller & Derek Simon (#208). Original airdate 11/28/2016.
The crossover begins Monday, Nov. 28, on the midseason finale of “Supergirl,” and continues Tuesday, Nov. 29, on “The Flash” and Wednesday, Nov. 30, on “Arrow” before concluding Thursday, Dec. 1, on “DC’s Legends of Tomorrow.”