Description
The relatives of Gabriel Broughton are summoned to Blackshaw Towers, an old, isolated country house in the middle of moorlands in Yorkshire, to hear the reading of his will. Gabriel's nervous nephew Ernest Broughton brings along his flatmate Syd Butler for support. At the large, gloomy mansion, they meet Guy Broughton, Ernest's cousin; Malcolm Broughton, a piano player who claims everyone is "quite mad"; Janet Broughton and Dr Edward Broughton, Guy's sister and father, respectively; Emily Broughton, a dotty old woman who believes the First World War is still on; and Linda Dixon, Gabriel's nurse. To their surprise, the solicitor Everett Sloane reveals that they have all inherited nothing, except for Linda, who is bequeathed Gabriel's medicines and syringe, much to her amusement.
The lights go out, and Ernest and Syd accompany Fisk, the butler, outside to try to effect repairs. They are unsuccessful, but on the way back, they find the body of Dr. Broughton. Syd states it was murder, but when he tries to telephone the police, he discovers the wire has been cut. With everyone stranded for the night, Sloane recommends they all lock themselves in their rooms. Ernest gets lost and enters Linda's room by mistake. She proposes that he stay the night with her, but beats a hasty retreat and persuades the imperturbable Syd to share his room.
When Ernest goes to use the toilet, someone tries to stab the sleeping Syd, then desists when he speaks up. Ernest starts playing "Chopsticks" on the organ. Malcolm joins him in a duet, but is stabbed in the back. Ernest's screams bring the others, and Sloane observes that the room was locked from the inside, so the solicitor recommends locking him in. Syd stays with Ernest, certain he is not the killer. They discover a secret passage, uncovering the means by which the murderer was able to leave the locked room. The survivors decide to remain together in the lounge for safety, but Janet is struck by a poison dart shot from behind a painting on the wall. They suspect Fisk, who was not present, but he has an airtight alibi. Sloane decides on his own to go to the village and fetch the police. When the others return to the room, Emily, who remained behind, insists she spoke to Gabriel. Syd and Guy check the coffin, but Gabriel's body is there. Then Ernest also claims he also saw Gabriel. He finds another secret passage that leads to the now empty coffin, and then Guy also disappears, along with a small pistol he had in his possession.
Finally, Police Inspector Arkwright arrives. He is skeptical that murders have been committed, especially since there are no bodies, but then Guy's is found. When Ernest goes to fetch Syd, they find the dead Sloane in a fountain outside, proving he could not have sent the policeman. However, the inspector - Gabriel in disguise - still manages to take them all prisoner with Guy's pistol. He explains his motive, that his relatives sponged off of him for years and treated him badly. He then locks up Syd, Ernest, Emily and Linda and sets starving dogs on them, but when he tries to shoot Fisk whilst fleeing, he misses and triggers a lethal trap instead, which drops a chandelier on him. The dogs, it turns out, were fed by Fisk, so they constitute no danger. The next day, to Ernest's disappointment, Linda's boyfriend, teen idol Adam Faith, comes to collect her.
