The Animal Liberation Alliance, an eco-terrorist group, saves a pregnant chimpanzee from an animal testing facility—only for her to deliver a half-human, half-chimpanzee "humanzee" called Charlie! Fifteen years on, Charlie's human foster parents are at last prepared to enroll him in a regular high school, where he befriends a human girl named Lucy. Meanwhile, however, the ALA's views have grown increasingly radical, and they are now intent on dragging Charlie into their terrorist scheme...