Urubu plot
George Breakston and Yorke Coplen plan to go on an expedition into the jungles of Matto Grosso, then fly from Los Angeles to Brazil. Their Brazilian guide is the explorer Mike Roginsky. Accompanied by Brazilian natives, Breakston and Coplen search for an English explorer who disappeared into the jungle twenty-five years earlier and is said to now be the leader of a group of Native Americans. Along the way, the expedition encounters an alligator, piranhas and a doctor who informs them about a teacher who has been captured by Indians of the Urubu tribe.