In Colombia, siblings Rudy and Gloria and their friend Pat prepare for a journey into the rain forest. They plan to prove Gloria's theory that cannibalism is a myth. The trio encounter two men named Mike and Joe. Joe is badly wounded; Mike explains that they were attacked by cannibals. During the night, Gloria goes missing and Rudy finds a native village while looking for her. Due to Joe's injuries, the travellers decide to stay in the nearly deserted village. Mike seduces the naive Pat and in a cocaine-fuelled rage, he encourages Pat to kill a native girl. She is unable to do it, so Mike kills the girl himself. In his dying moments, Joe reveals that he and Mike were responsible for the cannibals' aggression. They came to the region to exploit the natives for emeralds and cocaine. One day while high on cocaine, Mike brutally tortured and killed their native guide in full view of the tribe. A badly charred body, previously believed to be that of a different guide, is this native.