In the final-minutes of "Human for a Day," Hank Henshaw (David Harewood) came out of the superhero closet by revealing to Alex Danvers (Chyler Leigh) he is in fact DC Comics' iconic green-skinned shapeshifter Martian Manhunter, aka J'Onn J'Onzz.

Before he made that reveal, he made Alex promise not to disclose his secret to her sister Kara. At some point Supergirl has to find out the truth, but when?

Harewood told Entertainment Weekly that it will happen soon as "he actually pretends to be Supergirl" in an upcoming episode. "She gets to see Supergirl for the first time, as Kara," he added. "It’s quite a thing for her to see herself taking off and flying into the sky. It fills her with pride that there’s this female superhero. She looks awesome."

"Hostile Takeover" episode of Supergirl will air Monday, December 14 at 8PM on CBS.