On a dark and stormy night, a bus skids into a high-tension wire electrocuting all passengers but one: Dynamo Dan McCormick (Lon Chaney Jr.), who survives because he has built up immunity to electricity through his carnival performances. Dan is now the perfect specimen for the evil experiments of mad scientist Dr. Rigas (Lionel Atwill), who is working to create a race of electrically controlled men to do his bidding. The innocent Dan agrees to let Dr. Rigas study him but soon turns into a voltage addict manipulated by the doctor's commands. Before long, Dan becomes a monster whose fiery touch can, and does, kill.