The story begins with Lord Montbarry, who breaks off his engagement to Agnes Lockwood and marries the enigmatic Countess Narona. Montbarry and the Countess travel to Venice, where they stay in a decaying palazzo. Shortly after, Montbarry dies under mysterious circumstances, and his courier, Ferrari, vanishes. The palazzo is eventually turned into a hotel, and Agnes, along with Montbarry's family, visits it. The eerie atmosphere of the hotel heightens as strange occurrences unfold.