The DEO investigates the rash of dead animals; it spreads to humans, as people develop flu-like symptoms with a large scratch on their wrists. Imra believes this is the work of Pestilence, the third Worldkiller.
Kara and Mon-El fight Reign as Lena creates an antidote from the Harun-El. Once injected, Reign separates from Sam and disintegrates.
Two days after Kara’s defeat by Reign, the DEO and the Legion use the latter’s technology to heal Kara from her injuries. This saves her life but she remains in a coma.
Supergirl S03E13, Lena is poisoned with cyanide in her coffee by an unknown hitman. James pursues the hitman, who is eventually shot down by an unseen sniper.
Lena brings Sam out of sedation and tells her that her blood tests are normal, but further analysis shows Sam undergoes a metamorphosis at the cellular level when she becomes Reign