Francis Ingram is a noted pianist who lives in a large manor house near a small, isolated Italian village. Ingram suffered a stroke which left his right side immobile, and he has to use a wheelchair to get around. He has retreated to the manor house for the past few years—seen by only a few close friends. These include his nurse, Julie Holden ; a musicologist, Hillary Cummins ; a friend, Bruce Conrad ; and his sister's son, Donald Arlington. Ingram has fallen in love with Julie Holden, and has changed his will so that she receives the vast bulk of his enormous estate when he dies. But Julie is secretly in love with Conrad. The change in the will disinherits Arlington and Cummins, and Cummins tries to expose Holden's affair. Ingram, outraged at the slander on his beloved's good name, tries to choke Cummins to death. Only Julie's arrival saves him. Later that night, Ingram begins to suffer hallucinations from poison put in his food and drink. He climbs into his wheelchair, makes it to the top of the stairs, and calls out for Julie. Ingram falls down the stairs, breaking his neck. Commissario Ovidio Castanio of the local police investigates the death, but finds little sign of murder. A few days later, Raymond Arlington arrives, determined to ensure that his son gets the inheritance. Duprex, Ingram's attorney, is "persuaded" into helping Raymond overturn the new will in favor of the old one, telling him that there are suspicions regarding Ingram's death. That night, Duprex is murdered by an unseen assailant. Commissario Castanio begins to investigate. The Arlingtons try to search for the old will, while suspicion falls on Cummins after he tries to remove several expensive old books from the manor house. That night, everyone hears Ingram playing the piano in the main hall, but when they go to check no one is there. Donald, too, is attacked and almost choked to death. Commissario Castanio discovers that someone has broken into the Ingram mausoleum and that Ingram's left hand has been cut off. But it seems impossible for anyone to have gotten in or out. The audience now begins to see a disembodied hand moving around the manor house. The hand attacks Cummins, but he is able to assuage the hand's quest for vengeance by returning to the hand Ingram's signet ring. He locks the hand in a closet, but when Conrad and Holden appear to see what has happened — the hand has disappeared. Meanwhile, Donald Arlington remembers the combination and location of an old safe in the house, and Commissario Castanio and his father accompany him to the room where it is located. They discover the old will...and the disembodied hand. In a fit of madness, Donald Arlington flees the house with Conrad in pursuit. He comes to his senses, and is not harmed. Julie realizes that Cummins, who is now firmly convinced that the hand is out for vengeance and even sees it playing the piano, is responsible for the attacks and confronts him; he tries to kill her, but she is able to escape by claiming to believe his claims about the hand. Cummins tries to burn it in the fire, but the hand crawls out and chokes him, fading out of existence after he dies. Commissario Castanio and Conrad discover a hidden record player with a recording of Ingram's piano playing and conclude that Cummins had been playing it to scare people. He theorizes that Cummins cut off the hand, killed Duprex, and tried to kill Arlington. By that point, his mind had snapped, making him believe his own fabricated plot.
The film was Warner Bros.' only foray into the horror genre in the 1940s and was Peter Lorre's last film with the studio. Graham Baker was reported as working on a script for Warner Bros in 1945. Robert Florey was assigned to direct with Andrea King and Paul Henreid to star. The screenwriter Curt Siodmak had originally written the film for Henreid, who turned it down. Robert Alda was cast instead. Filming started 27 November 1945. The piece much played throughout the film is a slightly modified version of Brahms' transcription for left hand of the chaconne from Johann Sebastian Bach's Violin Partita in D minor, performed by Warner Bros. pianist Victor Aller. The hand of pianist Victor Aller is shown playing the piano and throughout the movie.
On Rotten Tomatoes, the film holds an approval rating of 89% based on, with a weighted average rating of 6.6/10. Author and film criticLeonard Maltin awarded the film two and a half out of a possible four stars, calling it " Intriguing, if not entirely successful mood piece". Bob Mastrangelo from Allmovie gave the film a positive review, calling it "effectively eerie", and praised the film's special effects.
