The mystery begins with the discovery of the body of old Robert Garth in the trampled mud of an ancient outhouse. The Garth family live at Garthmere Hall, which was ruled by Robert with a rod of iron. The Hall is a gloomy medieval building.When the local police officer Superintendent Layng investigates the murder, he doesn’t get very far, failing to win the confidence of the local people, finding their slowness in answering his questions frustrating and bewildering. So Chief Inspector Robert Macdonald from Scotland Yard is called in. There are a number of suspects, including a son who had just arrived after an absence of 25 years and a sister and two brothers of the murder victim who live at the gloomy Garthmere Hall.