Joseph Sheridan Le Fanu 
Room in the Dragon Volant 

The Room in the Dragon Volant is not really a supernatural tale. It does however have plenty of gothic elements and some genuine horror, and it’s an ingenious and entertaining tale. It’s set in France just after the end of the Napoleonic Wars, and involves a young rich Englishman who falls in love with a beautiful but mysterious, and unhappily married, countess. It also involves a room at the inn, The Dragon Volant, which has been the scene of mysterious disappearances. (Goodreads)