Story

At the Berlin Conference of 1884–1885, the Congo Basin is claimed by King Leopold II of Belgium. Five years later, after accruing massive debts in exploiting the resources of the Congo Free State, Leopold sends his envoy Léon Rom to secure the fabled diamonds of Opar. The expedition is massacred by warriors led by Chief Mbonga, who offers Rom diamonds in exchange for Tarzan. The man once called "Tarzan", The Rt Hon. John Clayton, Earl of Greystoke, has left Africa for his estate in Britain with his American wife, Jane, and embraced life as a wealthy nobleman. John's parents survived a shipwreck only to die in Africa, where their child, as a baby, was adopted by the Mangani, a race of apes. John is offered an invitation from Leopold to visit Boma. The Prime Minister and an American envoy, George Washington Williams, explain that Leopold is defaulting on his loans, and a visit from Greystoke – whose exploits as Tarzan made him a celebrity – would secure Britain's influence in the Congo. However, Greystoke refuses. George reveals to John his suspicions that Leopold is enslaving people and persuades him to go to the Congo to discover the truth. At Greystoke Manor, John remembers a time when he was 5 years old. After playing with his ape foster mother, Kala and foster brother, Akut, he was pursued by Kerchak. John, Jane, and George journey to the Congo, circumventing Rom and his corrupt financier Mr. Frum, and are welcomed by the Kuba village of John and Jane's youth. Rom and his men capture the villagers, killing Chief Muviro, and taking Wasimbu along with other young men to serve as porters. George rescues John, but Jane and the captive villagers are taken aboard Rom's steamship. Rom turns out to have arranged John's invitation from Leopold to deliver him to Mbonga. Pursuing the steamship, John, George, and the village's remaining warriors seize a train carrying Belgian officers and enslaved Congolese. An engineer informs them of Rom's plan to take over the Congo, sanctioned by Leopold: using slave labor, Rom has built forts across the region, linked by railway and river travel, for an army of 20,000 mercenaries soon to arrive. With Leopold bankrupt, Rom needs the diamonds of Opar to pay for the army. Finding documents that will expose Leopold, John and George leave the proof with the Kuba warriors and rescued slaves to deliver to Boma and continue on through Mangani territory. Confronted by the apes, John is forced to fight their leader, Akut. John loses, but he and George are permitted to travel on. Jane and Wasimbu escape the steamship and flee into the jungle. Jane sends Wasimbu off to rally the other tribes, knowing Rom's men will follow her. Jane encounters the Mangani, and Rom's men open fire on the apes. John arrives, saving some Mangani, and pursues Rom, who takes Jane to Mbonga's tribe. It is revealed that years ago, Mbonga's son killed John's foster mother, Kala. John killed him to avenge her. Mbonga attacks John, who wins the fight but spares the chief. George and the Mangani then arrive. The two foreigners convince Mbonga that Rom is their common enemy. Rom takes Jane and the diamonds to Boma, where the mercenary army approaches shore. John and George send a stampede of wildebeest through the town, overrunning Rom's men, as the Kuba warriors arrive by train and free their families. John rescues Jane and pursues Rom, who prepares to deliver the diamonds to Frum and the mercenaries. Williams sinks the steamship, while Rom strangles John with his rosary. Using a mating call to summon crocodiles, John breaks free and leaves Rom to be devoured. As the vessel's boiler explodes, John escapes. Frum and the fleet of mercenaries depart. George returns to London and presents the prime minister with an open letter to Leopold exposing the slavery and abuses of the Congolese people. One year later, John and Jane have relocated to Africa, in Jane's father's old house. They celebrate the birth of their son, and John returns to his rightful place among the great apes as Tarzan.