Primatologist Davis Okoye shares an unshakable bond with George, the extraordinarily intelligent gorilla who has been in his care since birth. But a rogue genetic experiment gone awry transforms this gentle ape into a raging monster. As these newly created monsters tear across North America, destroying everything in their path, Okoye teams with a discredited genetic engineer to secure an antidote, fighting his way through an ever-changing battlefield, not only to halt a global catastrophe but to save the fearsome creature that was once his friend.