A spoof on the mad scientist films of the 1950s. Alice Cable is a government agent sent to replace a man who has disappeared while guarding a secret experimental lab in the middle of the Louisiana bayous. Cable is soon wooed by Dr. Alec Holland, who is working on a concoction that combines plant and animal cells. Arcane is the criminal mastermind who is trying to steal the secret recipe for the potion. When Arcane and his mercenaries break into the government camp, they kill Holland's sister Linda, and the scientist is accidentally doused with his own formula and bursts into flames, then dives into the swamp. Arcane's men pursue Cable, but she is rescued by a mysterious green man. It takes several rescues for her to understand that the Swamp Thing is Dr. Holland, transformed by his own formula.