On the island of Mogahl, Looten Plunder and Dr. Blight have teamed up, and Blight's new cloning device will be used to clone workers for Plunder's flamethrower factory. They test it on the first living subject they find - a locust. But before they can capture the other one to test for side effects, it gets away. While searching for it, they come across Vico, a boy of a local village. He becomes the source for cloning workers for the factory. He becomes out of control with cloning when his appetite goes on a rampage, and threatens to wipe out the island. Now, the Planeteers (with the help of Captain Planet) must reverse the effects of the cloning ray, and also stop the locust(s) that have been cloned.

Sludge and four of the Planeteers learn first hand the terrible effects of untreated sewage when MAL and Dr. Blight shrink the EcoSub (and them) to microscopic size and put them into polluted water that Kwame unwittingly drinks. The Planeteers must battle hideous water-borne parasites in Kwame's body so that he can recover, and restore them to proper size.