He fought ghosts, werewolves, and satanists in over ninety stories, and one novel, between 1925 and 1951, assisted by Dr. Trowbridge (serving the same narrative purpose as Dr. Watson). Jules de Grandin and Dr. Trowbridge lived in Harrisonville, New Jersey. De Grandin was a French physician and expert on the occult and a former member of the French Sûreté who resembled a more physically dynamic blond, blue-eyed Hercule Poirot. Often, the supernatural entities in the mysteries are revealed not to be supernatural at all but the actions of insane, evil and depraved human beings.