The Planeteers argue about their priorities concerning different ecological problems. Sly Sludge dumps waste in a salt mine. Gaia assigns the Planeteers to intervene so they can end the dispute between themselves.
Linka leaves the Planeteers and returns home to look after her sick grandmother. Something is poisoning the water and the Planeteers begin to investigate. After they discover the culprit, Linka rejoins her friends.
Dr. Blight succeeds in constructing a machine, which switches the minds of two affected bodies. She manages to take over Gaia's body and Gaia herself inhabits Dr. Blight's body.
The Planeteers struggle to return endangered species to their habitats as they are being destroyed by the eco-villains. They end up rescuing far more animals than returning, to Gaia's dismay.
Gi visits a dolphin research center. Hoggish Greedly is behind a number of dolphins getting hurt due to his use of them to collect toxic waste from a submarine.
Zarm travels to the future and summons the great-great-great-grandchildren of 3 eco-villains. Captain Planet and the Planeteers can't handle the futuristic villains. Captain Planet is trapped and melted into a toxic acid bubble.
Wheeler's father is ill. Although they were never close, Wheeler heads back to New York. There he meets his old friends. Wheeler discovers that his friend Trish became Trash and turn to crime under Verminous Scum's orders.
The Planeteers go undercover to investigate a series of explosions at a plant. It turns Hoggish Greedly is behind the explosions, and the Planeteers call Captain Planet, who captures Greedly.