Edwin Dingle (Danny Kaye) and Buzzy Bellew (also Kaye) are twin siblings with opposite personalities. Hip performer Buzzy becomes a marked man after he catches big-shot gangster Ten Grand Jackson (Steve Cochran) in the act of killing an enemy. Jackson finds Buzzy and shuts him up for good -- or so he thinks. But Buzzy comes back in spirit form to inhabit the body of his introverted brother, and before long, Edwin is hunting down Jackson and puzzling everyone with his new persona.