 In Montreal, the industrial François Delambre (Vincent Price) is called late night by his sister-in-law Helene Delambre (Patricia Owens). She tells him that she has just killed her beloved husband Andre Delambre (Al Hedison), using the press of their plant to press his head and left hand. François calls his acquaintance, Inspector Charas (Herbert Marshall), and later the reluctant Helene is convinced to tell them what happened. She explains that François had invented a matter transportation apparatus, and while experimenting with himself, a fly entered the chamber, exchanging one hand and the head with him after the transference.