Dr. Janos Rukh discovers a certain type of radium that has almost magical healing properties. But the element has a dangerous side, too, and it has already started affecting Rukh. Consumed by paranoia, he begins to suspect that his wife is having an affair. Wild for revenge, Rukh hatches a deadly plot...using his own poisoned body as a weapon to kill.

Working in Dr. Cranley's laboratory, scientist Jack Griffin was always given the latitude to conduct some of his own experiments. His sudden departure, however, has Cranley's daughter Flora worried about him. Griffin has taken a room at the nearby Lion's Head Inn, hoping to reverse an experiment he conducted on himself that made him invisible. But the experimental drug has also warped his mind, making him aggressive and dangerous. He's prepared to do whatever it takes to restore his appearance.