Dr. Eric Vornoff (Bela Lugosi) is a mad scientist trying to create a race of superbeings. The process he uses, which includes clamping a metal lampshade onto the heads of his subjects and zapping them with radiation, usually kills them. However, Lobo (Tor Johnson) survives this experiment, and becomes the scientist's assistant. Together they conduct experiments on trespassers into his swamp. When Vornoff tries to get nosy reporter Janet Lawton (Loretta King) to mate with Lobo, things become difficult. Janet's fiance, along with local police, decide to go to Vornoff's old house to find Janet. What they find instead may surprise them.