A 1985 film directed by Creator/JohnBoorman, based on a true story.

Bill's son is kidnapped by an Amazon tribe. Bill tried to pursue but lost them in the jungle. Over a decade later, he tries to arrange an expedition to find his son. The results are a disaster. His partner is eaten by cannibals and he flees only to find his son as one of the natives trying to kill him.

Tommy, now a young man, recognizes his father and helps him escape. Tommy takes him to friendly natives who care for Bill. Bill learns of how completely Tommy has transformed into a tribal man speaking their language as if it was native and as if his father's language was foreign. Then the tribe drugs Bill and takes him back to civilization. Bill wakes up with no clue where his son is.

A deadly conflict arises between some of the natives and the ones who ate Bill's partner try to kill Tommy's adopted family. Tommy goes on a quest into the city even though he's a tribesman. He finds his dad and the two of them rescue Tommy's adopted family. Bill helps the tribe further as Tommy returns to the jungle to live.

!! ''The Emerald Forest'' contains examples of:
* TheAmazon: Set where the city clashes with the jungle.
%% * TheCaptivityNarrative: Subverted on two counts: It's a boy and his tribe is rescued.
%% zero-context, and is it really a subversion?
* GoingNative: Tommy was forced to go native in the beginning but even when he had the chance to return to the city, he stayed a native.
* LanguageBarrier: Downplayed since both Bill and Tommy understand a little of each other's language but they still have very different native tongues.