The Circular Staircase

Rachel Innes, a middle-aged spinster, has barely settled in at the country house she has rented for the summer when a series of bizarre and violent events threaten to perturb her normally unflappable nature. A strange figure appears briefly in the twilight outside a window. At night, a rattling, metallic sound reverberates through dark halls, and-most disconcerting of all-the body of a strange man is found lying in a pool of blood at the bottom of a circular staircase.
Before this spine-tingling tale ends, five connected deaths shatter the normally placid atmosphere of the vacation retreat. Rachel's devoted niece and nephew are among the prime suspects in one of the murders; stolen securities and a bank default threaten the young pair's financial security, and Aunt "Ray" ultimately fights for her life in an airless secret room.