Four students (Meche, Toño, Manuel, and Edwin) travel to the jungle to conduct research. Manuel becomes friendly with a local girl named Yaqui. That night, a party is held, which the students, Yaqui, and other local youths attend. Yaqui ventures deeper into the jungle and is attacked by the Yara, a jungle spirit. The Yara, disguised as Yaqui, seduces Edwin and Manuel and drowns them in the river. She is about to do the same to Toño, but he is rescued by Meche. The bodies of Yaqui, Edwin, and Manuel float down the river. The next day, Meche sets off on a raft with Manuel, who is still very weak from the previous night's events. As the raft drifts away, we see Meche's body lying drowned in the river. The one piloting the raft is actually the Yara.