The Haunted Hotel: Annotated Edition by Wilkie Collins
An enigmatic countess is tormented by a dark secret. An English aristocrat, Lord Montbarry, falls ill and dies in a decaying Venetian palazzo. An Italian servant disappears, and his wife receives a note containing one thousand pounds. With the palazzo now transformed into a luxury hotel, and the late Lord Montbarry's family in residence, these strands begin to come together, yet strange and macabre events are occurring, and the dead seem unable to rest.