When Cunda, a man living deep in the Brazilian rainforest, is bitten by a snake, he has a hallucination of four chimpanzees. Once he recovers, he is shocked to find the four chimpanzees waiting for him at home, and, believing them to be special, decides to take them to the city in order to sell them.
According to an Amazonian legend, every month, during the full moon, a Brazilian fishing village receives a mysterious guest: the Boto, who transforms into a human to seduce and be loved by women and hated by men. One of her conquests is the daughter of a fisherman, who has a son with the Boto. He constantly reappears to seduce her, and even when she marries, he continues to look for her. This provokes the ire of the husband, who wants to kill him anyway.
Bill Markham, un ingeniero estadounidense, supervisa la construcción de una presa en la selva amazónica. Mientras está trabajando, unos indígenas raptan a Tommy, su hijo de siete años. Diez años más tarde, Bill consigue encontrarle viviendo con la tribu Los Invisibles, a la que Tommy, ahora Tomme, pertenece. Esto dará lugar a un significativo choque cultural entre ellos.
