Primatologist Davis Okoye prefers to stay away from humans and befriends George, a remarkably intelligent male gorilla he's raised since birth. But a genetic experiment gone out of control turns the docile ape into a fierce monster. What's more, it's soon discovered that other modified predators exist. While the freshly created monsters turn North America into ruins, wiping out everything in their path, Okoye, along with a disgraced genetic engineer, tries to invent an antidote, tearing through an endless battlefield, not only to prevent a global catastrophe, but also to save the fearless creature who was once his friend.