Ankers portrays an aviatrix who walks out of the jungle looking decades younger than her chronological age due to a secret fountain of youth but gradually begins a terrifying accelerated aging process. Against Tarzan’s wishes, she and Jane begin a desperate search for the fountain.
Varga (Fernando Wagner), a villainous white pearl thief posing as the god Balu has chooses a lovely young native girl, Mara (Linda Christian) to be his bride. She escapes the island of Aquatania and meets Tarzan (Johnny Weissmuller) and Jane (Brenda Joyce) who agree to help her and she gives Jane a rare black pearl. She is recaptured, however, and taken back to the island. Tarzan goes to her rescue. Tiko (Gustavo Rojo) to whom Mara is betrothed meets Jane. Benji (John Laurenz), the singing mailman takes Jane’s pearl to the region’s commissioner, who decides to visit the island, picking up Jane and Tiko along the way. They are captured and Varga’s henchman, Palanth (George Zucco), in his role as high priest, is about to sentence them to death when Tarzan, disguised as Balu, arrives to have them released. Tiko and Mara are about to be married when the real Balu appears and all the outsiders are ordered to be thrown to their deaths into the sea. Tarzan unmasks the false god and the two villains meet the fate they had tried to impose upon the others.
Due to a shortage of animals in American zoos following World War II, Tanya Rawlins, a big-game “huntress,” Carl Marley, her financial backer and Paul Weir, a cruel trail boss, are given permission by King Farrod, to capture a male and female of each species of animal on his land.
In a subplot, Oziri, nephew to King Farrod, colludes with Weir to allow him to trap more animals than bargained for. He also has Weir’s men kill King Farrod and his son, Prince Suli, in order for him to take over the throne. Farrod is shot in the back and killed, and Suli is thrown into a pit full of crocodiles, but, unknown to all watching, he lands on a hidden ledge and is knocked unconscious.
Boy trades two lion cubs to the trappers for a flashlight. When Tarzan finds out, he returns the flashlight, retrieves the cubs, and calls all the animals from King Farrod’s land across the river to his part of the jungle. When the hunters begin trapping on his side of the river, Tarzan and Boy sneak into their camp at night, take their guns and hide them in a cave behind a waterfall. They then begin to systematically release all the trapped animals from their cages.
Cheeta inadvertently reveals the location of the cache of weapons to Rawlins and her safari.
Prince Suli is able to make his way through the jungle, and is found by Tarzan. Tarzan, Boy and a herd of elephants defeat both the usurping nephew and the huntress, but the latter escapes onboard a plane.
Travellers 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, and Boy take in Kimba, a boy who claims to have become lost in the jungle. Kimba (Tommy Cook) 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.
Kimba has a goal of his own: to take the heart of Jane (Brenda Joyce) a deed that would make him a warrior in the eyes of the cult. The Leopard Men wear leopard skins that form a cowl and cape, with iron claws attached to the back of each hand. Queen Lea (Acquanetta) wears a headband, wrist bands, ankle bands, halter top and miniskirt made of leopard skin. As “Variety” put it: “She displays plenty of what it takes to stir male interest and handles her acting chores adequately.” She works her followers into a frenzy in an underground chamber, “These skins are your disguise. These claws are your weapons. Go not as men, but as leopards. Go swiftly, silently.”
They attack a caravan bringing four teachers (Iris Flores, Lillian Molieri (Miss Central America of 1945), Helen Gerald and Kay Solinas) and bring the maidens back for sacrifice. They also capture Tarzan, Jane, and Boy. Tarzan brings down the roof of the cavern, destroying the cult and rescuing his friends.
Tarzan and Boy, on their way to meet Jane, who is returning from nursing work in England to support the war effort, rescue an “Amazon” woman from an attack by a black panther. During the attack, she drops a golden bracelet which Cheeta picks up. The Amazon woman’s ankle is twisted in the incident and she cannot walk. Telling Boy to wait for him, Tarzan carries the woman through a mountain pass to the valley where her city of Palmyria is located. Boy disobeys Tarzan, follows them at a distance, and discovers the location of the city, then returns to wait for Tarzan.
After they reunite with Jane, a group of explorers, led by Sir Guy Henderson, discover the bracelet Cheeta has, and its markings are matched to other relics supposedly from a lost city of Amazons. The explorers attempt to enlist Tarzan to lead them to Palmyria. Tarzan refuses, but Boy, believing he is aiding the advancement of science, is duped into guiding them there.
Boy and the party are captured by the Amazons, and their queen declares that in lieu of the death penalty for invading their city, they will all be forced to work the rest of their lives in the Palmyrian quarries with the other men they keep for labor. The woman Tarzan saved from the panther takes pity and releases them. The group, led by Ballister, Henderson’s unsavory second-in-command, and Anders, then sets about looting the city’s treasure vaults. When Henderson objects, Ballister kills him, then fatally knifes the woman who released them. She is able to sound an alarm before she dies, and the invaders are all killed save Ballister and Anders, who escape with two pieces of treasure.
Boy is recaptured and condemned to die. Cheeta warns Tarzan of Boy’s impending doom. Tarzan races to Palmyria, meets Ballister and Anders, and backs them into a mud bog in which they sink and die. He returns the Amazon’s treasure in exchange for Boy’s freedom.
The film revolves around Tarzan’s quest, at the urging of Jane, to find a rare African serum to help Allied troops. Tarzan’s son, Boy, manages to tag along as the apeman journeys into the Sahara, and the two are soon joined by a rambunctious horse and a female American magician, played by Nancy Kelly. The story is mostly a fantasy adventure—with “Arabian Nights”-style characters and sinister Nazi spies—but it also includes considerable comic relief and even science fiction elements. Critics complained that it was aimed more toward juvenile audiences than previous Tarzan films had been.
Tarzan and Boy are living on the Great Escarpment, though Jane has returned to England. 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”.
Only when Boy is kidnapped by the Germans does Tarzan shout, “Now Tarzan make war!” Tarzan infiltrates the lost city, destroying a machine gun and defeating the German invaders with his knife and an elephant blitzkrieg. The film’s final scene has Cheeta speaking into the defeated Germans’ short wave radio to call Berlin; the Germans mistake Cheeta for Adolf Hitler.
Circus workers land an airplane in the jungles of Africa in search of lions for their show. While trapping lions, the three men meet up with Tarzan, Jane and their adopted son Boy. Watching Boy’s tricks with the elephants, the head of the circus, Buck Rand (played by 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 a plane back to the United States. Tarzan’s loyal chimp Cheeta wakes Tarzan and Jane before they are burned by the fire. Then Cheeta tells Tarzan that Boy has left with the men on the plane.
Tarzan, Jane and the chimp track across the jungle and eventually end up in New York City where Tarzan is befuddled by the lifestyle and gadgetry of “civilization”. Tarzan displays his quaint, “noble savage” ways by complaining about the necessity of wearing clothing, commenting that an opera singer that he hears on a “noisy box” is “Woman sick! Scream for witch doctor!”, and expressing his childlike wonderment at taxi cabs. It is noteworthy that Tarzan comments that various African-Americans he sees making a living throughout New York City are from this or that tribe back in their jungle home.
Tarzan and Jane attempt to get Boy back first by legal means. This leads to a moving sequence where the judge asks Tarzan what the fishing is like back in Africa and what he considers to be important things that he needs to teach his adopted son. Unfortunately, the circus retains an unscrupulous lawyer who tricks Jane into admitting that Boy was not born in the jungle and is not her actual child and provokes Tarzan into attacking him in the court room. Tarzan makes a daring escape out the courtroom windows and after a rooftop chase by the police ends up doing a high dive off the Brooklyn Bridge into the East River.
Tarzan somehow finds the circus where Boy is being held and enlists the aid of circus elephants who are chained to stakes. He calls to them with his “jungle speak” and they take their revenge on their tormentors by tearing free from the chains and destroying the circus. In the ensuing bedlam, Tarzan is able to rescue Boy, and in the film’s conclusion the judge grants Tarzan and Jane full custody of Boy before the family returns to Africa.
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. Soon the group is captured by natives, whereupon Tarzan comes to their rescue.
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 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 a fortune worth millions. Jane tries to help the search party and Boy go back to civilization, against Tarzan’s wishes.
