The Circular Staircase

According to Wikipedia: "Mary Roberts Rinehart (August 12, 1876-September 22, 1958) was a prolific author often called the American Agatha Christie.[1] She is considered the source of the phrase "The butler did it", although she did not actually use the phrase herself, and also considered to have invented the "Had-I-But-Known" school of mystery writing.... Rinehart wrote hundreds of short stories,...