In prehistoric times, an asteroid crashing to Earth ends the age of dinosaurs, while in the present day industrialist John Greystoke, Mark Deklin, funds an expedition to Uganda to locate the meteor and harness its energy. Aided by scientist James Porter, the effort ends in failure, and John decides to depart with his wife and their son, hoping to leave the mystery behind.
While flying over a semi-active volcano, the Greystokes' helicopter falters and must land on the meteor itself. John explores a cave and discovers glowing rock formations, and when he uses his pickaxe to sample them, a chain reaction rouses the volcano. Their escape is thwarted as the helicopter crashes, and only the boy survives. He is found by Kala, a Mountain gorilla who has recently suffered a loss, and she adopts him into her troop. Adopting the name Tarzan, Kellan Lutz grows up learning the ways of the jungle.
After the Greystokes vanish, Dr. Porter funds further expeditions by working as a jungle guide for wealthy tourists. During a routine safari, a client strays from the group, drawing the attention of a cassowary. Jane saves him by placing herself in danger, even as she is bitten by a viper. Infatuated with the girl, Tarzan carries Jane to a shelter and nurses her back to health, though she returns to her father’s camp with only hazy memories of the night.
Confused by exposure to humans after so long, Tarzan decides to leave his ape family and eventually wanders to the site of the helicopter crash. There he finds the meteor rock his father took and builds a shelter to survive. Years later, Tublat, the apes’ abusive leader, circles Tarzan’s refuge and inadvertently triggers the helicopter’s emergency beacon. The signal is received by Greystoke Energies. Clayton, its current CEO, Trevor St. John sees a chance to profit and promises Jane, who now works for a conservation group, funding in exchange for joining his Africa trek to speak with her father.
In Africa, Jane is repulsed by Clayton’s greed. She leaves the party, wanders into the jungle, and encounters Tarzan, now a man. He guides her to his hidden refuge, and as a mark of their growing bond, Tarzan gives her a piece of the meteor rock. The rest of the group closes in, and Clayton is stunned to realize the Greystoke heir is alive. Seeing Tarzan as a threat to his power, Clayton opens fire, forcing the couple to flee into a valley blighted by meteor-induced mutations that transform flora and fauna into terrifying forms.
Together they endure numerous perils and eventually reach the meteor, where Tarzan recognizes his father’s long-abandoned pickaxe. Jane discovers Tarzan’s true identity as John’s son, and Tarzan returns to his ape tribe to claim his place as leader, introducing Jane to Kala and challenging Tublat for authority. In the ensuing clash, Tarzan defeats Tublat and exiles him, while Tarzan and Jane confess their love that night.
Meanwhile, Clayton reshapes Dr. Porter’s base into a mercenary stronghold. A fierce confrontation erupts between the lovers and Clayton’s men. Kala rushes to protect Tarzan and Jane, but is wounded by gunfire. Tarzan is captured and placed in a cage, yet with the help of his gorilla friends he escapes, carries Kala to safety, and vows revenge. Clayton shifts his operation toward the meteor, rigging it with explosives as a last-ditch bid for triumph. Jane and her father are rescued, but the meteor’s awakening reopens the volcano as Tarzan summons the jungle’s forces with a cry, sending the surrounding mountain to crumble.
Clayton and his crew fall to their deaths, while Tarzan and Jane escape to safety. The couple is finally reunited with Tarzan’s family, pledging to protect the forest they call home. Dr. Porter, meanwhile, clings to the meteor’s edge, climbing the cliff to secure a remaining fragment as the drama closes.
