Tarzan discovers a missile while chasing Cheetah, perhaps nuclear, so Jack makes a call to US forces. When Buzz McAllister appears, Tarzan takes him to the weapon but the rest learn Buzz is actually a rogue arms dealer. Learning of the deception, Tarzan and his adversary fight near a snake pit.
Ben and Jim emerge uninjured from a plane crash, telling Tarzan they were traveling to a martial arts competition. Tarzan is confused about that kind of fighting and Cheetah brings a mysterious powder from the downed aircraft that Jane analyzes. The two men are smugglers and Tarzan must battle them to save his friends.
Tarzan and Cheetah discover a leaking barrel of pesticide, causing Cheetah's friend Tolki to rampage through camp. Jane, trying to cure the infected chimp, becomes sick and heads into the jungle hallucinating. Tarzan must find Jane and give her the antidote.
Sleeping sickness has broken out and local authorities response threatens the animals of the jungle. Tarzan vows to prevent this but is injured swinging through the jungle and reverts to someone who doesn't speak or know Jane. In a race against time, Jane must help Tarzan return to his usual self.
While looking for water during a drought Jane and Roger discover oil. A sheik arrives, willing to destroy the jungle to get the oil while Tarzan vows to do everything to stop him.
Jane and Roger are busy and they harshly ask Cheetah and Tantor to leave them. The animal friends run away towards an area with a dangerous lion and Tarzan goes to rescue them after explaining to Jane and Roger that animals have feelings.
Jack wins a hot air balloon in a poker game and offers to teach Roger how to fly it but on their intial flight they crash far from camp. Contacted by radio, Tarzan and Jane go on an overnight journey to rescue them and grow closer.
Bruno escapes from prison, armed with dynamite, seeking deadly revenge on Tarzan and his friends. After Jane, Roger, and Carl are subdued and tied up, Bruno heads to the tree house to end Tarzan's time as protector of the jungle.
Roger discovers an old mine in the lagoon and after it explodes, a creature rises from the water. The rest doubt Roger's account but after it kidnaps Jane, Tarzan goes after the manfish. But does the creature actually mean any harm?
Jack's first love visits a singer recovering her voice, hoping to stay in the jungle. Jack fears she won't be happy there, that she'll leave and he'll never see her again.
Jane and Roger's lives are at risk when he wrecks the jeep in an area where fire comes from the ground. An angry Jane berates Roger, hurting his pride. Roger returns to the site to prove his worth and Tarzan follows to secretly help him.
Jane agrees to host famous movie star Nick Dimato as a favor to Roger's father but the actor annoys everyone with his arrogance. Refusing to heed Tarzan's warnings about the jungle's dangers, Nick needs rescuing repeatedly.
Kiki Bluet, an attractive cosmetics heiress, crashes in the jungle and Tarzan takes her to the compound. Roger and Jack are very attentive, making it easy for Kiki to get them to help her. But she leaves Roger in danger in her quest for a secret ingredient to an anti-aging face cream.
Roger mentions to Tarzan that Cheetah is more pet than wild animal so Tarzan resolves to return his ape friend to the jungle. Jane insists that she and Roger go along but it happens that they need rescuing, not Cheetah.
Roger and Jack are both attacked by a secret man in the jungle. As they recover, Jane discovers the river is being poisoned so Tarzan seeks the reason for these problems. He discovers his enemy Manuel who is using chemicals to mine uranium.
Paul Shaka returns to the jungle after leaving as a young boy. Tarzan agrees to escort Shaka back to his village but isn't told the trip is being sabotaged as a rite of passage by a witch doctor.
Roger is severely burned while swimming by a chemical substance coming from a pipe. After treating Roger, Jane joins Tarzan in finding the origin of the toxin which turns out to be the villainous Hauser. Tarzan must battle Hauser before he despoils the water.
Tarzan encounters a burning mist that is killing trees and small animals. He finds the man responsible, Gonzalez who claims to be testing a defoliate to combat the drug trade. But Tarzan and Roger discover the truth which endangers their lives.