"When the student of medicine, Richard Bracquemont, decided to move into room #7 of the small Hotel Stevens, Rue Alfred Stevens (Paris 6), three persons had already hanged themselves from the cross-bar of the window in that room on three successive Fridays." The last of them was a police sergeant who had volunteered to sleep in the room to learn what happens that might explain the hangings, and somehow he met with the same fate. The medical student was aware of these...