"A Christmas Eve" is a short story by Camillo Boito which appeared in his anthology of decadence and perversity titled Tales of Vanity (sometimes translated as Vain Tales), which also featured his more famous work, the novella Senso. The story deals with a young man who is sexually obsessed with his recently deceased twin sister. Deeply depressed on Christmas Eve, he picks up a prostitute that bears a striking similarity to his dead sibling, but spending the night with her only sends him further into complete madness. This short story is known for bearing a similarity to one of Edgar Allan Poe's lesser known works, Berenice. Source: Wikipedia (en)