Johnny Weissmuller's take on Tarzan
James Parker (C. Aubrey Smith) and Harry Holt (Tarzan) (Neil Hamilton (actor)) travel in Africa on a quest for the legendary elephant burial grounds and their ivory. They are joined by Parker's daughter Jane Porter (Tarzan) (Maureen O'Sullivan). Holt is attracted to Jane, and tries somewhat ineffectively to protect her from the jungle's dangers. He notably fails to prevent her abduction by the jungle's guardian, the mysterious Tarzan (Johnny Weissmuller) and his ape allies.
Tarzan and his wife Jane Porter (Tarzan) live in the jungle, along with their chimpanzee Cheeta. Harry Holt (Tarzan) and his business partner Martin Arlington, leading a large party of locals, meet them on their way to take ivory from an elephant burial ground. Holt had visited the burial ground with Tarzan on an earlier trip, during which he had also met Jane. Holt had sought Tarzan out, as he was the only one who knew the way to the burial ground. On this trip, Holt tries to convince Jane to return with him to civilization by bringing her gifts such as clothing and modern gadgets. Jane tells him she would rather stay with Tarzan. She does agree to convince Tarzan to act as their guide.
An expedition seeking to bring Jane back to civilization, and Tarzan into captivity, gets more than it's bargained for.
A plane flying to Cape Town, carrying a young couple and their baby, crashes in the jungle. Everyone on the plane dies, except for the baby who is rescued by Cheeta, Tarzan's Common chimpanzee. Tarzan and Jane adopt the child and name him "Boy." Five years later, a search party comes looking for Boy, because he is the heir to the Greystoke family fortune worth millions. The search party is led by the Lancing family, who are distant cousins of Greystoke. Tarzan and Jane claim the child is dead and that Boy is theirs, but the elder Lancing, Sir Thomas, recognizes Boy's eyes. The younger Lancings suggest leaving Boy and taking the inheritance. When Sir Thomas objects, they say they will take him back and, as legal guardians, still control the inheritance. Sir Thomas says he'll tell Tarzan, but the rest of the party imprison Sir Thomas in a tent and plan to abduct Boy. Tarzan overhears them plotting; he steals their guns and throws them into a deep lake. Jane arrives the next day and learns what has taken place, and admits that Boy is Greystoke. She persuades Tarzan to retrieve the cache of guns, without which the search party can't survive. Tarzan retrieves them but Jane drops the rope so that Tarzan is trapped.
An expedition team arrives on Tarzan's escarpment. By chance, the two villainous members Medford (Tom Conway) and Vandermeer (Philip Dorn) find out that there is plenty of gold on the escarpment. They kidnap Jane and Boy in order to make Tarzan show them the location of the gold. After Tarzan complies, Medford shoots him and mistakenly presumes he is dead. Soon the group is captured by natives, whereupon Tarzan, comes to their rescue.
Workers land an aircraft in the jungles of Africa in search of lions for their circus. While trapping lions, the three men meet with Tarzan (Johnny Weissmuller), Jane (Maureen O'Sullivan) and their adopted son Boy (Johnny Sheffield). Watching Boy's tricks with the elephants, the head of the circus, Buck Rand (Charles Bickford), realizes that Boy would be a great act for the circus. The group is attacked by natives, and it appears that Tarzan and Jane have perished in a jungle fire. The men take Boy on their aircraft and return to the United States. Tarzan's loyal chimp Cheeta wakes Tarzan and Jane before they are burned-to-death by the fire. Cheeta tells Tarzan that Boy has left with the men on their aircraft.
Tarzan and Boy are living on the Great Escarpment, though Jane has returned to England to tend to her sick mother. A small force of German paratroopers lands and takes over the lost city of "Palandrya" as an advance base for the conquest of Sub Saharan Africa. Tarzan continually ignores the requests for help from the helpless and enslaved Palandrians, saying, "Jungle people fight to live, civilized people live to fight."
Like its immediate predecessor, ''Tarzan Triumphs'', the film makes reference to Tarzan's mate, Jane, played in earlier Weissmuller films by Maureen O'Sullivan, but it does not show her on screen. The explanation given is that she is in England helping the war effort. (When the character of Jane finally did return in the next Tarzan film, she was played by Brenda Joyce (actress), not O'Sullivan.)
Travelers near Zambezi are being killed, apparently by leopards. The commissioner (Dennis Hoey) asks Tarzan to look into the matter. Tarzan immediately doubts that leopards are the problem. At the same time, Tarzan, Jane Porter (Tarzan), and Boy take in Kimba, a boy who claims to have become lost in the jungle. Kimba Tommy Cook (actor) is the brother of Queen Lea, leader of a leopard cult. She has dispatched him to spy on Tarzan. Queen Lea also conspires with Ameer Lazar (Edgar Barrier), a Western-educated doctor who resents the West's domination of the area.
To escape from an arranged marriage to Aquatania's pagan god, a desperate maiden ends up in Tarzan's fishing net. But soon, he, too, finds himself before a well-planned conspiracy. Can Tarzan save the mermaid from the barbaric idol's will?
