Mary Roberts Rinehart (August 12, 1876-September 22, 1958) was an American writer, 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. She is considered to have invented the "Had-I-But-Known" school of mystery writing.When a Man Marries is a romantic comedy with mystery overtones the plot unfolds as several Bright Young characters suddenly find themselves sequestered in a large house under quarantine because the butler has just been stricken with smallpox.