Astrologist Hilary Cummins (Peter Lorre) works as a personal assistant to the eccentric and mostly paralyzed pianist, Francis Ingram (Victor Francen). A nurse, Julie Holden (Andrea King) also lives at the Italian villa to help care for Ingram, who plays the piano with only his undamaged left hand. Following a visit from a scam artist (Robert Alda), Ingram crashes down the stairs to his death -- and a plague of bizarre events ensues that are attributed to the musician's disembodied left hand.