In the Bornean rainforest Dr. Anne Russon, primate psychologist, broaches new territory in the attempt to understand orangutan intelligence and psychology. Orangutans, like humans, have "culture." They do not rely solely on animal instinct for survival. Instead a rich and complex society of elders and peers provides the young with critical knowledge that is necessary for their survival in the rainforest. The destruction of the orangutan's habitat to make way for palm oil plantations and the illegal pet-trade threaten the lives of these great apes. When they are taken out of their habitat or when it is destroyed, their culture is disabled.
Dr. James Brewster (Bela Lugosi) and his colleague Dr. Randall (Henry Hall) are involved in a series of scientific experiments which have caused him to transform into an ape-man. In an attempt to obtain a cure Brewster believes that it will be necessary to inject himself with recently drawn human spinal fluid. When Randall refuses to help him by providing the fluid, Brewster and his captive gorilla must attempt to find an appropriate donor.
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, 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.
Deep in the South American jungles, plantation manager Barney Chavez (Burr) kills his elderly employer in order to get to his beautiful wife Dina Van Gelder (Payton). However, old native witch Al-Long (Gisela Werbisek) witnesses the crime and puts a curse on Barney, who soon after finds himself turning nightly into a rampaging gorilla. When a wise but superstitious police commissioner Taro (Chaney) is brought in to investigate the plantation owner's death and a rash of strange animal killings, he begins to suspect that all is not as it seems. Dina is also becoming suspicious of Barney, who seems to be more in love with the jungle than with her. She follows him one night into the jungle, only to be attacked by the feral Barney. The police chief follows her screams in the jungle and shoots Barney.
An airplane crashes in the jungle, stranding passengers Gamage Dean (Yolande Donlan), Diana Penrod (Betta St. John), "Doodles" Fletcher (Wilfrid Hyde-White), Carl Kraski (George Coulouris), and Dick Penrod (Peter Arne). Before the plane slides into a gorge the group is rescued by Tarzan (Gordon Scott), who undertakes to lead them back to civilization. Diana is kidnapped by warriors from Opar under Chief Ogonooro (Orlando Martins). The Oparians desire the strangers as sacrifices for their lion god. She is recovered by Tarzan and hunter Tusker Hawkins (Robert Beatty), whose advances Diana rebuffs. Secretly, however, Hawkins is in league with the Oparians, and plans to sell the castaways to the natives for a fortune in ivory. Tarzan, rightly suspecting Hawkins' untrustworthiness, exposes his treachery. Now openly in league with the natives, the hunter helps them take the white party captive in Tarzan's absence. The ape man returns to save them before the sacrifice can take place, aided by his chimpanzee ally Cheeta, who sets fire to the native village. He then leads them to the safety of a nearby settlement. Hawkins meets his fate at the hands of the Oparians, to whom Tarzan has signaled his double-dealing by a creative use of jungle drums.
À la suite d'un accident d'avion, un petit singe capucin né en captivité, se retrouve seul dans la forêt amazonienne. Pour lui commence une grande aventure.
Mickey est l'employé de Tony dans sa boutique d'animaux. Mais l'un des pensionnaires, Beppo le gorille, arrive à s'échapper de sa cage. Il prend en otage Minnie. Mickey se bat contre les animaux de la boutique afin de sauver sa fiancée.
Mickey consulte les informations et apprend qu'un gorille s'est échappé. Paniqué, Mickey appelle Minnie, qui n'est nullement effrayée, chantant une chanson pour le montrer. Mais le gorille arrive derrière elle et l'attrape. Mickey court précipitamment pour la sauver.
Tarzan sauve une jeune Amazone des griffes d'un tigre, sous les yeux de Boy et de Cheeta. Il la ramène dans la cité perdue de son peuple, endroit qu'il est le seul à connaître. Mais Boy l'a suivi et découvre ce site merveilleux. Jane revient d'Angleterre, accompagnée d'un groupe de savants dirigé par Sir Guy Henderson. Un bracelet en or pur, perdu par l'Amazone, tombe entre leurs mains. Si Henderson n'est là que pour observer des civilisations disparues, d'autres membres de l'expédition se montrent plus cupides. Jane est chargée de convaincre Tarzan de leur montrer le chemin de la cité.
Krazy and his spaniel girlfriend (who is wearing a blond coily wig in this short) are attending an outdoor party organized by a community of apes. The apes sing, dance, and play instruments. Krazy and the spaniel join in the activities. But the celebration of the apes gets interrupted when their master, a labrador holding a whip, shows up. It is shown that the apes are forced laborers who work on sowing and harvesting crops for little rewards.
The Bantons (father, Abel (John Carradine) and four sons, Coy (Jock Mahoney), Ethan (Ron McDonnell), Johnny (Gary Cockrell) and Martin (Al Mulock)) rob a pay office in a settlement, killing some people. Coy Banton is tracked down to their camp and taken away by a policeman, Wyntors (John Sullivan). Taking him back to town, Wyntors is killed as two of the brothers seek to rescue Coy. Tarzan appears and kills Ethan Banton. The other brother escapes. Tarzan decides to take Coy to Kairobi for the $5000 reward so he can give it to Wyntors' widow. However, no one in the town of Mantu (same town as beginning of Tarzan's Greatest Adventure) wants to help him. The boat he is waiting for to take him and his prisoner to Kairobi is ambushed by the Bantons, who send the passengers off and destroy the boat.
The plot involves a disparate and desperate group of plane crash survivors thrust into a savage mountainous desert region somewhere within present-day Namibia. Brian O'Brien - played by Stuart Whitman - is a big game hunter and the best survivalist of the group. Shortly after his plane crashes, stranding its passengers, he risks his life by re-entering the burning wreck and recovering vital supplies, including a hunting rifle; however, O'Brien's motives are far from noble. Thinking his own chances will be improved by the absence of competition, he ruthlessly eliminates his fellow survivors, one by one, intending to leave only Grace Munkton (Susannah York) alive, an "Eve" for his "Adam."