When the Danvers celebrate Thanksgiving, Alex tries to find the right time to tell her mother Eliza that she's gay. Meanwhile, Lena is forced to choose when Supergirl tells her that Lillian plans to unleash a virus that will wipe out every alien in the city.

Crossover among four CW shows: Supergirl "Medusa"; The Flash "Invasion!"; Arrow ‘Invasion!"; DC's Legends of Tomorrow "Invasion!"

Livewire escapes prison, but the DEO soon realizes that she wasn't a willing escapee. Meanwhile, Megan collapses and Hank refuses to mind-meld with her to find out what is wrong with her, and James considers telling Kara that he's Guardian.