Primatologist Davis Okoye keeps his distance from people and shares a close bond with George, an exceptionally intelligent alpha male gorilla he has raised since birth. When a failed genetic experiment turns George into a raging monster, Okoye discovers that other modified predators have also been set loose. As the creatures tear through North America, he teams up with a disgraced genetic engineer to develop an antidote, hoping to stop the catastrophe and save his friend.