Believing that Swamp Thing can grant him immortality, Anton Arcane turns three swamp thugs into human-animal hybrids, the Un-Men, and sends them to capture him. Instead, they capture two lost boys, so Swamp Thing and friends intervene.
Arcane takes a native Amazonian tribe hostage in order to force them to assist him in his quest for eternal life. It's up to Swamp Thing and the gang to stop him and rescue the tribe.
A nuclear satellite crashes in the swamp and while Swamp Thing wants to retrieve the satellite in order to protect his domain from contamination, Arcane wants it to make super strong radioactive Un-Men.
A benevolent but misguided female scientist and her assistant capture Swamp Thing to learn how his DNA works. Anton Arcane turns more of his henchmen into mutants to retrieve Swamp Thing and experiment on him himself.