Scientist André Delambre (David Hedison) has invented a matter transporter. To perfect his machine, he decides to test the device on a human subject -- himself. He steps into the chamber unaware that an ordinary housefly has accompanied him. His head and arm become horrifically switched with those of the fly. Now Delambre and his wife (Patricia Owens) are faced with a gruesome dilemma in this classic sci-fi horror co-starring Vincent Price.