In a new clip from "The Girl Who Has Everything," the next episode of "Supergirl," Non reveals to Astra that he gave Kara the Black Mercy, an alien parasite that causes the host to believe she is living her greatest desire. The Black Mercy sends Kara back to a Krypton that was never destroyed -- something Non believes is a mercy she doesn't deserve.
According to the official episode description, "Kara’s friends must find a way to save her life when a parasitic alien attaches itself to her and traps her in a dream world where her family is alive and her home planet was never destroyed. Also, Alex, Hank and the DEO must fend off a Kryptonian attack while Kara is out of commission."
The episode is an adaption of Alan Moore and Dave Gibbons' classic Superman story "For the Man Who Has Everything," which originally appeared as 1985's "Superman Annual" #11. In the comic, Superman fell victim to an alien plant known as the Black Mercy, a parasite that attaches itself to Superman's chest and forces him into a catatonic state where he dreams of his perfect life that could have been, had Krypton never exploded. Eventually, the dream turns bad, and Superman overcomes the Black Mercy's powers.
"Supergirl" airs Mondays at 8 pm EST on CBS. Developed by producers Greg Berlanti, Ali Adler and Andrew Kreisberg, the series stars Melissa Benoist, Calista Flockhart, David Harewood and Chyler Leigh.