"The Circular Staircase" is a mystery novel written by Mary Roberts Rinehart, published in 1908. The story follows the character Rachel Innes, who rents a country house and becomes embroiled in a series of strange events, including a murder. The narrative is told through her perspective, blending suspense with elements of humor. The novel is notable for its use of the unreliable narrator and has been influential in the development of the mystery genre. It features themes of family secrets and the supernatural, making it a compelling read for fans of early 20th-century literature.