Tarzan, having acclimated to life in London, is called back to his former home in the jungle to investigate the activities at a mining encampment.

Following his parents' death in Africa, John Clayton has been be raised by an ape, was known by the name Tarzan, but eventually left Africa and for his parents' home in England, along with the woman he fell in love with and married, Jane Porter. He is asked by Belgian King Leopold to go to Africa to see what he has done there to help the country. Initially, he refuses. But an American, George Washington Williams, wants him to accept so he can accompany him.

He says that Leopold might be committing all sorts of atrocities to achieve his goal, like slavery. Clayton agrees and his wife insists that she accompany him because she misses Africa. When they arrive, a man named Rom, who works for Leopold, attacks their village and captures Tarzan and Jane. With Washington's help he escapes and sets out to rescue Jane by going across the jungle. Washington joins him despite being told that he might not make it.