The Spider by Hanns Heinz Ewers

"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 incidents, but...

"There was one detail about which he knew nothing because neither the police inspector nor any of the eyewitnesses had mentioned it to the press. It was only later, after what happened to the medical student, that anyone remembered that when the police removed Sergeant Charles-Maria Chaumié's body from the window cross-bar a large black spider crawled from the dead man's open mouth. A hotel porter flicked it away, exclaiming, 'Ugh, another of those damned creatures.'"

Thus begins this bizarre mystery of "The Spider."