The Emerald Forest

Bill Markham is an engineer who has moved to Brazil with his family to complete the construction of a large hydro-electric dam. The construction requires large areas of forest to be cleared, even more to be flooded. Its completion will bring more people to the areas who will clear the jungle for agriculture and living space.When the film opens, Markham has taken his family to the edge of the forest for a picnic to show them the jungle and the progress of the dam's construction. The site is abuzz with workers and machines cutting and clearing, but is situated right on the edge of a vast expanse of dense and unexplored Amazon terrain. His young son, Tommy, aged seven, wanders from the cleared area to just inside the treeline where he amuses himself by feeding his picnic snacks to the large jungle ants. It is then that an Indian from one of the indigenous tribes known as the Invisible People notices him, and is struck by the boy's blonde hair and bright green eyes, which are the colour of the forest. Tommy sees the tribesman, who smiles warmly at him and speaks softly in his language. Young Tommy then runs out of the treeline to inform Markham that the jungle is full of "smiling people" but his father laughs him off skeptically, telling him he'll be right there to check it out. When Tommy returns to the treeline just ahead of Markham, the tribesman decides that it is unfair to leave the child with these strange people, who, in his opinion, are destroying the world. He abducts the child. As Markham realises his son has just been taken, a warning shot from an unseen archer lands in a tree near his head. Regardless of the arrow, Markham pursues them, calling upon all the nearby construction workers to help. Frantically hacking his way through the undergrowth, Markham comes to a ridge in a clearing that reveals before him an endless valley of dense jungle. His son is gone.The story jumps ahead some ten years. The dam is nearing completion. Tommy, or Tommé as he is now called, has become part of the tribe that he lives with, adopting their language, culture and way of life. The tribesman who took him is revealed to be the chief of the Invisible People, and has taken Tommé for his own son. Tommé is depicted going through rituals of manhood and courtship, becoming involved with a beautiful member of the tribe named Kachiri. After their marriage ceremony, he undergoes a vision quest, where his spirit animal shows him what he must do to help his tribe: retrieve the sacred stones from a remote spot deep in the jungle, at the foot of a waterfall. The sacred stones are essentially a mossy-green clay, out of which the Invisible People make their signature body paint that allows them to blend in so seamlessly with the jungle. The chief of the tribe informs Tommé that the quest will be dangerous, as the Fierce People have moved into the area. The Fierce People are a hostile tribe of cannibal warriors, who ironically had been displaced from their own lands years earlier by the beginning of the dam's construction. They are now coming into uncomfortably close proximity to the Invisible People.Meanwhile, in the years after their son's abduction the Markham family has not given up hope of finding Tommy. Bill's wife Jean is now a social worker, heavily involved with orphans and displaced children. Bill himself has become well versed in tribal Amazonian culture in his search for the elusive people who took his son, to the extent that he has become nearly fluent in a few local Indian dialects. One day Bill hosts a particularly obnoxious journalist who is doing an exploitative piece of the subject of Markham's search among Indian peoples, and the two of them set off for a mission on the river. The only clue Markham has to seek out answers is the arrow that was originally shot at him when his son was abducted. Because of the particular fletching used in the arrow, local Indians on the river are able to identify the tribe that Markham has been seeking, and inform him that he quite unsurprisingly hasn't found them up until this point because they are known as the Invisible People. However, Markham and his journalist companion, whose cynicism and sarcasm concerning indigenous peoples is beginning to wear on him, set off for a likely place along the river where they intend to camp and set off fireworks and bottle rockets to attract the attention of any uncontacted but curious tribes in the region. Unfortunately, the tribe they do stumble upon happens to be the Fierce People, who quickly take them into captivity. Markham, who is armed with a CAR-15 carbine, is able to defend himself adequately and just long enough to have an exchange with the leader of the Fierce People. The chief informs Markham that he admires his tenacity, comparing him to a jaguar, and that after a night's head-start into the jungle he will be hunted at daybreak. The journalist is not so lucky, and is gutted on the spot by the tribe's women. Markham then flees the jeering Fierce People into the jungle, firing bursts from his carbine into the darkness behind him.Shortly after dawn, Markham, in hot pursuit and low on ammunition, stumbles into the foot of a waterfall and sees a young Indian underneath the falls gathering stones. Right before he shoots, the young Indian steps forward toward Markham and is revealed to be Tommé, and the two instantly recognise each other. The moment is shattered when the Fierce People burst from the jungle above and behind them in full force, during which Markham takes an arrow in the shoulder. Tommé and his father fight off the Fierce warriors and manage to escape downriver, but Markham loses his carbine in the process.Back home with the Invisible People, Markham spends time recovering from his injuries and fighting off a fever. He comes to understand his son's transformation and the tribe's way of life, forging a begrudging respect for the chief who took him as a child. Markham himself undergoes a vision quest, discovers his spirit animal, and wakes up back in civilisation having been dropped off by the Invisible People at the edge of the dam's construction zone while he was unconscious.During these events, it is revealed that the chief of the Fierce People has been busy trying to figure out how to work the carbine Markham left behind, which he immediately understands is a formidable weapon. The chief is seen working himself up into a rage whilst stuffing bones and rocks into the firing chamber of the carbine in an increasingly desperate and futile attempt to make it shoot. Later, at a seedy brothel and cantina on the edge of the construction zone, the Fierce People wander from the jungle with the M4 in hand to essentially ask someone from civilisation how to work the thing. Seeing an opportunity, the unscrupulous owners of the brothel manage to communicate to the Fierce People that if they are brought some women (motioning to the adjacent jungle) that they would then give the Fierce warriors all the guns and bullets they wanted.When coming back to their village from taking Markham back home, Tommé and his friends in the tribe discover to their horror that the village has been violently raided, many have been killed and all their young women are missing. It is then discovered that the Fierce People have sold them all to the brothel for rifles and liquor. Tommé and his best friend from the tribe then embark upon a harrowing quest into the city, where he will find his old home according to his childhood memory, and ask his father for help. During the journey, the two tribesmen meet and are helped along by two other young men who are revealed to have been former members of the Bat People tribe, but who now live in the city. Tommé manages to navigate from memory to his parents' multistory condo, which he climbs like a tree. Tommé is seen by his mother during this encounter for the first time in a decade. Markham agrees to help Tommé and his tribe by rescuing all the women from the brothel.Coordinating his attack with the Invisible People to take place at night, while all the members of the Fierce People are wildly drunk outside the building, Markham initiates a shootout in the brothel whilst all the women are sprung from captivity. However, during the attack, several members of the Invisible People are killed, including the chief, Tommé's adopted tribal father. In the aftermath of this event, Tommé becomes chief of the tribe. Markham warns Tommé that the dam, imminently nearing completion, will bring more people, reduce more jungle, and likely end their way of life, but Tommé is obstinate, insisting that the rains will wash the dam away when the frogs sing loudly enough.Soon afterward, during a particularly bad storm, Markham places demolition explosives at key points along the dam, blowing it up during the peak of the rains. With the dam washed away, Tommé and the tribe can live in relative peace for a little while longer.The film ends with Tommé and Kachiri sitting at the swimming hole near their village in the jungle, watching the members of their tribe splash and play. The tribe even includes a few new members in the two young men from the Bat People who had helped Tommé earlier. Tommé and Kachiri laugh together and leisurely speculate on which members of the tribe would make good couples.

Question: Who blew the up the dam?
Answer: Markham