Die All, Die Merrily — Leo Bruce

Richard Hoysden's body is discovered in his country flat, a revolver beside him, and a bullet through the head, apparently a suicide. Missing from the room is a tape of Hoysden's last moments on which he confesses ti the murder of a young woman. Lady Drombone, a member of Parliament and the dead man's aunt, hires Carolus Deene to help suppress the evidence. He must reconstruct the confusing circumstances in order to solve this baffling crime.