Mary Roberts Rinehart 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.

Allegheny City was a municipality that existed in the U.S. state of Pennsylvania from 1788 until it was annexed by Pittsburgh in 1907. It was located north across the Allegheny River from downtown Pittsburgh, with its southwest border formed by the Ohio River, and is known today as the North Side. The city's waterfront district, along the Allegheny and Ohio rivers, became Pittsburgh's North Shore neighborhood.