Deep in the African jungle, native women are being abducted by Pico Church, henchman for corrupt lawyer Arco, who wants to set tribes against one another so he can control the area through the criminal leadership of M'Gono. Professional guide Jungle Jim, absent from the jungle for three months, returns and meets territory police Lt. Barry, who informs him of the recent uprisings and says that Commissioner Kingston needs Jim's assistance in an arraignment against M'Gono. Barry tells Jim that Arco, M'Gono's lawyer, is suspected of being behind M'Gono's attacks and the kidnappings, but proof is needed. Going to Watsabi, Jim and Barry come across Church, who kills his latest kidnapping victim before fleeing. At the arraignment, M'Gono is charged with murdering a constable, but Arco proves the victim was not a certified officer of the law and the charge is dropped. As the circuit judge will not be in the area for another six months, M'Gono is freed until new charges can be levied. Kingston worries that the tribes will perceive M'Gono as a hero and assigns Jim and Barry to escort government agent Mr. Bradley through the jungle to conduct critical tribal treaty negotiations. Bradley is traveling with interpreter Ellen Shaw, whose missionary father was killed in the recent native uprisings. Meanwhile, Church reports his discovery of a small oil well to Arco, who notes that the oil is located in M'Gono's territory of River Valley, which years earlier was known as Valley of the Head Hunters. Later, Church eavesdrops on Bradley telling Jim that his mission includes getting approval from the tribal chieftains to lease mineral rights for copper to the government. Jim does not believe the natives will comply, but agrees to escort Bradley and Ellen down the river. Church reports to Arco, who resolves to force M'Gono's tribe to resume their violent head hunter past and then blame it on the government, so that he can take over the mineral leasing rights to access the oil. Arco presents his plan to M'Gono, who would subdue all the tribes and as their supreme chief would sign the land lease rights over to Arco. When Arco threatens to abandon M'Gono at his next court date, he accepts and with his men disguised as head hunter warriors destroys a nearby village. Jim takes Bradley, Barry and Ellen down the river, but the government agent has no success negotiating with the two tribes. Jim and the group hear native drums announcing the village burnings, and during the following week, several more are attacked. On board their boat, Bradley and Jim meet with chieftains Bagava and Gitzhak who, despite their respect for Jim, blame the government for instigating the attacks as a means to force them to sign the land treaty. Meanwhile, Arco tells M'Gono he has convinced several tribal chieftains that Jim is responsible for the attacks and that if M'Gono brings in a captive Jim to the upcoming tribal meeting, he will be made chief of the territories. The next day Jim and his group are ambushed by M'Gono's men, and at the tribal meeting, all the chiefs except Bagava and Gitzhak select M'Gono as their leader. Later, Jim's chimpanzee Tamba steals a knife and frees Jim. Jim seizes Church and gets him to confess Arco's plan and then forces him to repeat the disclosure to Bagava and Gitzhak. Just then, Arco and M'Gono's men attack, freeing Church and capturing Jim, Bradley and Barry, but Jim creates a diversion and all three manage to escape. Jim then plans to trap Arco and his men between the dangerous lion's grotto and Bagava's village, while Barry brings a boat up the river to cover all avenues of escape. In the clash, Church is killed and M'Gono and Arco finally subdued. Later, Bagava and Gitzhak sign Bradley's treaties and promise to encourage the other chieftains to do the same, and peace returns to the jungle.