A Haunting in Venice is the third film in a series of movies that follow the uncanny investigations of Belgian Detective Hercule Poirot. Poirot is a detective who appears in over 30 novels, 2 plays, and dozens of short stories by Agatha Christie. A Haunting in Venice is based on Christie's book, "Hallowe'en Party."
Source:https://www.cbr.com/best-twists-a-haunting-in-venice/