Mary Roberts Rinehart (August 12, 1876September 22, 1958) was an American writer, often called the American Agatha Christie. Rinehart published her first mystery novel The Circular Staircase in 1908, which introduced the "had I but known" narrative style. Rinehart is also considered the source of "the butler did it" plot device in her novel The Door (1930), although the exact phrase does not appear in her work. She also worked to tell the stories and experiences of front line soldiers during World War I, one of the first women to travel to the Belgian front lines. Biography Rinehart was born Mary Ella Roberts in Allegheny City, Pennsylvania, now a part of Pittsburgh. A sister, Olive Louise, four years Mary's junior, would later gain recognition as an author of children's books and nationally syndicated newspaper columnist. Her father was a frustrated inventor, and throughout her childhood, the family often had financial problems. Her father committed suicide when Mary was 19 years old. Left-handed at a time when that was considered inappropriate, she was trained to use her right hand instead. She attended public schools and graduated at age 16, then enrolled at the Pittsburgh Training School for Nurses at Pittsburgh Homeopathic Hospital, where she graduated in 1896. She described the experience as "all the tragedy of the world under one roof." After graduation, she married Stanley Marshall Rinehart (1867–1932), a physician she had met there. They had three sons: Stanley Jr., Alan, and Frederick. During the stock market crash of 1903, the couple lost their savings, spurring Rinehart's efforts at writing as a way to earn income. She was 27 that year, and produced 45 short stories. In 1907, she wrote The Circular Staircase, the novel that propelled her to national fame. According to her obituary in the Pittsburgh Post-Gazette in 1958, the book sold 1.25 million copies. Her regular contributions to The Saturday Evening Post were immensely popular and helped the magazine mold American middle-class taste and manners. In 1911, after the publication of five successful books and two plays, the Rineharts moved to the Pittsburgh suburb of Glen Osborne, where they purchased a large home at the corner of Orchard and Linden Streets called "Cassella." Before they moved into the house, however, Mrs. Rinehart had to have the house completely rebuilt because it had fallen into disrepair. "The venture was mine, and I had put every dollar I possessed