Black Christmas is a 1974 Canadian slasher film produced and directed by Bob Clark, and written by Roy Moore. It stars Olivia Hussey, Keir Dullea, Margot Kidder, and John Saxon. The story follows a group of sorority sisters who receive threatening phone calls and are eventually stalked and murdered by a killer during the Christmas season. Inspired by the urban legend "the babysitter and the man upstairs" and a series of murders that took place in the Westmount neighbourhood of Montreal, Quebec, Moore wrote the screenplay under the title Stop Me.