The Twilight Zone: Season 1, Episode 29

1 - 29: Nightmare as a Child

A young girl named Markie is sitting outside the apartment of schoolteacher Helen Foley. Upon being invited into Helen's apartment, Markie seems to make Helen feel uncomfortable with how much she knows about her. It is ultimately revealed that Markie is there to help Helen remember the events of her mother's murder before the killer returns to take care of loose ends.