The Secret of the Sacred Forest (1970)

Provost plays a brave teenager who sneaks into the Philippines in order to search for his brother, Parsons, a famed investigative reporter whose plane crashed in the middle of the jungle while he was trying to expose a drug-smuggling ring. American embassy official Merrill learns the boy has entered the country illegally and heads off into the bush after him. In the meantime, Provost has found a guide, native boy Martinez, to help him in his search. Pursued by black marketeers, unsympathetic government agents, headhunters, and Merrill, Provost finds his brother and is shocked to learn that he is a member of the drug-smuggling ring. The confusion ends, however, when Parsons explains that he staged his disappearance in order to join the smugglers so that he could expose them.