Dr. Decker (Michael Gough), a botanist and university professor, is the sole survivor of a plane crash in Africa. When he returns from the jungle he brings with him a baby chimpanzee, 'Konga' (Paul Stockman). During the course of his experiments, Decker discovers a serum that causes Konga to grow to the size of a gorilla - and, eventually, to obey his will. Encountering both opposition to his experiments and a potential love affair thwarted by a rival, he decides to put the supersized ape to terrifying use...