A weekend gathering at a country estate turns deadly when one of the guests is found murdered. Lord Caterham's house party is disrupted by the discovery of a dead body in the drawing-room. Inspector Roderick Alleyn of Scotland Yard is called to investigate, facing a house full of suspects, each with their own secrets and motives. The victim, a notorious gambler named Dix, was known for his unpleasant nature, making the list of potential killers long and the path to the truth obscured by a web of deceit and social maneuvering.

A Man Lay Dead is recognized as the inaugural novel by Ngaio Marsh, establishing her as a significant voice in the Golden Age of Detective Fiction. Critics at the time and since have noted its skillful plotting and the introduction of the sophisticated Inspector Alleyn. The book adheres closely to the conventions of the country house mystery, providing a satisfying puzzle for readers. Its reception highlights Marsh's ability to blend intricate mystery with engaging character portrayals, setting a strong foundation for her subsequent works.