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.

A shipping disaster in the 19th Century has stranded a man and woman in the wilds of Africa. The lady is pregnant, and gives birth to a son in their tree house. Soon after, a family of apes stumble across the house and in the ensuing panic, both parents are killed. A female ape takes the tiny boy as a replacement for her own dead infant, and raises him as her son. Twenty years later, Captain Phillippe D'Arnot discovers the man who thinks he is an ape. Evidence in the tree house leads him to believe that he is the direct descendant of the Earl of Greystoke, and thus takes it upon himself to return the man to civilization.

The film starts off with a woman and a baby on a plane. The plane, for no apparent reason, fails and crashes into a jungle. The baby survives and is adopted and brought home by a gorilla named Shina. She brings him to her troop, where he is ridiculed for being different from the rest of them. The yet to be named baby is allowed to stay on the condition that he is to go if he causes any trouble. Shina names him Lord and he quickly adjusts to life as a gorilla.