This comedy thriller by Mary Roberts Rinehart and Avery Hopwood was based upon a 1908 story titled "The Circular Staircase." It opened on 23 August 1920 at the Morosco Theatre and ran an amazing 878 performances, starring May Vokes and Effie Ellsler as a maid and her employer contending with odd events in a country house.
The Historical Dictionary of the American Theater. James Fisher.