When a group of chimpanzees freed from a research facility goes on a ravenous rampage, the virulent disease they carry quickly becomes a horrifying human pandemic. And when a bicycle courier (Cillian Murphy) awakes from a coma in a deserted London Hospital, he finds himself in a post-apocalyptic world where survival of the fittest means staying a few steps ahead of the infested... who create more of their own by ravenously attacking the fit!