Years after leaving the jungles of Africa behind, John Clayton III, also known as Tarzan, has acclimated to life in London as a member of the British aristocracy with his beloved wife, Jane. He's invited back to the Congo to serve as a trade emissary of Parliament, unaware that he is a pawn in a deadly convergence of greed and revenge plotted by the corrupt Belgian Captain Léon Rom. Rom's ambition is to capture Tarzan and deliver him to an old enemy in exchange for diamonds that will secure Belgium's colonial empire in the Congo.

Tarzan reluctantly returns to the Congo with Jane and an American envoy, George Washington Williams, who suspects the Belgians of enslaving the Congolese population. Although his return rekindles his affinity for the jungle and its wildlife, it also reignites the animosity of Chief Mbonga, who has a personal vendetta against him. As Tarzan and Jane reconnect with the communities and friends from their past, they are unwittingly drawn into Rom's sinister plan, leading to Jane's capture by Rom as leverage against Tarzan. With the stakes raised, Tarzan must navigate the dangers of his former home, confront his historical enemies, and uncover Belgium's imperialistic schemes before it is too late.