Season 1 Episode 13
"For the Girl Who Has Everything"
A parasitic alien attaches itself to Kara and traps her in a world where Krypton was never destroyed, leaving Alex, Hank and the DEO to fend off a Kryptonian attack without her.
Agent Danvers finds Kara in her apartment with a parasite feeding off her.
Kara is caught in a dream world of her home planet.
Astra and Supergirl say their last goodbye's.