Supergirl and her allies face down a version of Power Parasite, with elements of Lovecraft and Environmentalism. James Olsen, whose comic-book career has had him play superhero more than once, makes his first appearance as obscure DC superhero, The Guardian.

On The Flash, Alchemy plots something diabolical, Wally wants to become Kid Flash, Caitlin reveals her powers, a new metahuman casts shade, and the new Harrison continues to irritate. And why is Barry’s new labmate not around? Could he be….?

Here’s the place to discuss this week’s first half of CWDC Universe shows.