A small-town doctor's experiments leave a trail of dead bodies.

Expelled from his studies in medical research in Vienna, Dr. Peter Blood, a frustrated biochemist, returns to the Cornish village where his father is a general practitioner. Certain that by utilizing a South American arrow tip poison he can transfer the heart of a "worthless" living person to a "worthy" corpse and restore life, Peter kidnaps several villagers and uses them as living subjects for the experiments he is conducting in an abandoned mine. He becomes attracted to his father's nurse, Linda Parker, whose husband died in an accident a year ago and who is still grieving. Eventually, Linda discovers Peter's activities and threatens to expose him, but Peter exhumes her husband's corpse and gives it the heart of a hobo he has abducted. Faced with the horrible sight of her revivified husband, Linda becomes hysterical. Peter seizes the living corpse when it attempts to strangle Linda, and the doctor and his monster become locked in a death struggle. As they destroy each other, Linda stumbles from the mine.