The novella opens on a Christmas Eve in the last decade of the 19th century, some 50 years after the events of the main story. In an old house a group has gathered by the fire to exchange ghost stories. Among the party is the Prologue’s narrator, whose identity remains unknown. A tale of a boy haunted by spirits has just ended, and someone remarks that such stories rarely feature children. This prompts a man named Douglas to say, “If the child gives the effect another turn of the screw, what do you say to two children—?” (3). The room resounds with calls to hear his story. Although Douglas initially demurs, saying, “It’s quite too horrible” (3), he finally relents. He cannot immediately relieve his audience’s suspense, however, as he must first send for the story’s manuscript, which is at his house in town.

The manuscript, existing “in old faded ink” (4), was written by a woman whom Douglas met when he was a university student, during a holiday at home. She was his sister’s governess, and 10 years older than Douglas, but they became fond of one another and spent hours together, walking and talking.