The story revolves around the protagonist, Mrs. Drover, who returns to her childhood home in London after years away, only to be confronted by the ghost of a past love and a haunting letter that reveals a dark secret. The story explores themes of:
* Haunted memories: The past intrudes on Mrs. Drover's present, reminding her of a past love affair and a promise made in a moment of desperation. This past haunts her both emotionally and physically.
* The fragility of identity: The letter and the presence of the "demon lover" challenge Mrs. Drover's understanding of her own identity and the choices she has made in her life.
* The power of the unknown: The story is filled with a sense of unease and mystery, leaving the reader to question the nature of the supernatural and the true motives of the demon lover.
Ultimately, "The Demon Lover" is a meditation on the ways in which the past can shape the present, leaving characters haunted by their past choices and struggling to come to terms with the consequences of their actions.