Zod and his soldiers release a virus into the air that turns humans into zombies. The only way to stop it is to make an antidote from the blood of another Kryptonian. After Lois is infected, Chloe pleads with Clark to donate his blood to stop the epidemic, even though it risks outing him to Zod.
original airdate--October 9,2009 rating--2.30 million
song--Theme song--"Save Me" by Remy Zero
Trivia: Jody Thompson appears as a police officer who makes out with Oliver. She also appeared as Gia in Season Five's Fade, where she kissed Clark.