Rick Hellar is a troubled teenager living alone with his mother, Margaret, who immerses herself in her work as an animal behavioral scientist. Rick occupies himself by quickly becoming the chief of misbehavior and trouble-making. Unable to control her son, Margaret hands him the duties of cleaning up her lab... a job which Rick learns to loathe. It is in the lab where Rick finds a companion of equal disobedience in Katie, a three-year-old gorilla. As the bond of friendship grows, Katie's owner, Gus Charnley, stakes claim on the gorilla to be an animal attraction at his flea market. Rick cannot bear the fate of his furry friend, and, with the help of a recluse, sets out to free her.