Four young Americans are entangled in a web of deceit and corruption while doing anthropological research in a Campa Indian village. Living among the natives of the upper Ucayali River turns deadly as the Shining Path, a group of Communist guerrillas, shows its true colors, wreaking chaos and destruction on the village and its inhabitants. Determined to stop the brutal group of killers, Mark Erwin abandons his academic pursuits and sets his sights on a more dangerous quarry.