"The House of the Arrow" by A. E. W. Mason is a mystery novel published in 1924. When a wealthy widow dies in Dijon, her niece Betty stands accused of murder by poison. Inspector Hanaud arrives to investigate, discovering cryptic clues including a missing arrow coated with untraceable poison and a suspicious clock. As the detective unravels a web of sealed rooms, secret passages, and carefully staged alibis, he must distinguish truth from deception before the killer strikes again. (This is an automatically generated summary.)