In the 1880s, an English couple and their infant son escape a burning ship, ending up on land near uncharted rainforests off the coast of Africa. The couple craft themselves a treehouse from their ship's wreckage, but are subsequently killed by Sabor, a rogue leopardess. Kala, a female gorilla who recently lost her own child to Sabor, hears the cries of the orphaned human infant and finds him in the ruined treehouse. Though she is attacked by Sabor, Kala and the baby manage to escape. Kala takes the baby back to the gorilla troop to raise as her own, an act of which her mate, Kerchak, disapproves. Kala raises the human child, naming him Tarzan. Though he befriends other gorillas in the troop and other animals, including the young female gorilla Terk and the paranoid male elephant Tantor, Tarzan finds himself unable to keep up with them, so he takes great efforts to improve himself. As a young man, Tarzan is able to kill Sabor with his crude spear and protect the troop, gaining Kerchak's reluctant respect.
It has been years since the man once known as Tarzan (Alexander Skarsgård) left the jungles of Africa behind for a gentrified life in London as John Clayton III, Lord Greystoke, with his beloved wife, Jane Porter (Margot Robbie) at his side. Now, he has been invited back to the Congo to serve as a trade emissary of Parliament, unaware that he is a pawn in a deadly convergence of greed and revenge, masterminded by the Belgian Captain Rom (Christoph Waltz).
John, Lord Clayton (Paul Geoffrey), the heir to The 6th Earl of Greystoke, and his wife Alice (Cheryl Campbell) set sail and are quickly shipwrecked on the African coast. After John (or 'Jack') builds a home in the trees, Alice gives birth to a son. Soon after, Alice grows delirious and dies. When Lord Clayton finds her recently dead, the tree house is visited by curious gorillas, and John is killed by one of the apes. The female of the group, Kala, carries her dead infant, but upon hearing the cries of the infant human in his crib, she adopts the boy and raises him among the family of Mangani. The little human child thus grows up naked, wild, and free.
70,000,000 years ago, a mountain-sized meteor, bristling with unknown energies, crashed into the Earth in what is now the Yucatán Peninsula in Mexico, with a major chunk of the object landing in Central Africa. The impact and resulting ecological catastrophe causing the extinction of the dinosaurs.
James Parker is a hunter in Africa, searching for a mythical "white ape". He is joined by his estranged daughter, Jane, after her mother's death. They discover the "white ape" is actually Tarzan, an uncivilized white man raised by apes living in the jungle. James continues to pursue Tarzan with the purpose of capturing him, dead or alive, and bringing him back to England.
Circus workers land an aircraft in the jungles of Africa in search of lions for their show. While trapping lions, the three men meet up 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 an aircraft 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.
James Parker (C. Aubrey Smith) and Harry Holt (Neil Hamilton), in Africa on a quest for the legendary elephant burial grounds (and their ivory), are joined by Parker's daughter Jane (Maureen O'Sullivan). Holt, attracted to her, tries somewhat ineffectively to protect her from the jungle's dangers, notably failing to prevent her abduction by the jungle's guardian, the mysterious Tarzan (Johnny Weissmuller) and his ape allies.
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. Tarzan and Jane claim the child is dead and that Boy is theirs, but 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 of 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.
Jungle medics Dr. Sturdy (Carl Benton Reid) and his daughter Anne (Jil Jarmyn) are opposed by witch doctor Futa (James Edwards) of the Nagasu tribe, who regards their work as a threat to his own livelihood. Futa incites the tribe to waylay Anne's fiance Dr. Ken Warwick (Harry Lauter), who is saved by Tarzan (Gordon Scott). Later Tarzan and his adopted son Tartu (Rickie Sorensen) enlist the doctors' services on behalf of Jane (Eve Brent), suffering from appendicitis. Futa hypnotizes Moto (Nick Stewart), a native assistant of Sturdy, to murder Jane, but Tarzan thwarts the plot. Learning that the young Nagasu chief (Roy Glenn) is sick, Tarzan attempts to persuade them to let Sturdy treat them. Seizing his chance, Futa has the ape man taken captive and condemned to death. To restore his own credentials, the witch doctor then undertakes to cure the chief himself, hedging his bets by having his henchman Ramo (Woody Strode) steal medicine from Sturdy. Unfortunately, Ramo purloins a poison by mistake. Freeing himself, Tarzan intervenes and prevents the administration of the poison to the chief; Futa then swallows it himself to demonstrate that there is no harm in it — and dies. Dr. Sturdy is consequently called in, successfully curing the chief.
The plot of the film reprises that of the 1932 version, with James Parker (Douglas) Harry Holt (Danova) and Parker's daughter Jane (Barnes) on an expedition in Africa in which they encounter Tarzan, a wild man raised by apes. Various adventures ensue.
A native village is robbed, supposedly by natives. Before a man dies, he mentions the name "Slade". Black colouring is found on his hand so they know it is white people who did it, disguised as Africans. Tarzan arrives, remembering Slade from a year previously as a man who let three of his men die during a hunt for a rogue elephant and has a grudge against him. A woman (Angie) turns up, Sanchez' latest woman, flying one of his planes. Later she buzzes Tarzan in his canoe, and crashes the plane so now Tarzan is stuck with her as he goes after Slade. Slade has 3 men and a girlfriend with him. He knows where a diamond mine is and has got his supplies for his trip by stealing them. Tensions run high amongst his men. Kruger is an ex-Nazi and a diamond expert. O'Bannion is an Irish rebel, a drunk and a trouble maker who keeps hassling Dino till Dino decides to kill him but falls foul of a wild animal and quicksand.
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.
The film makes use of a frame tale to present three self-contained "episodes" via flashback. Jane and Tarzan's first wedding anniversary has arrived, and Jane is trying to find a suitable present for her husband, with the help of the elephant Tantor, and the gorilla Terk.