[1] The plot concerns the fallen nobility of the house of Mazzini, on the northern shore of Sicily, as related by a tourist who learns of their turbulent history from a monk he meets at the ruins of their once-magnificent castle.

However, their escape has been anticipated, and the Marquis ambushes and seemingly kills Hippolitus, whose body is carried away by his servants.

Mazzini and De Luovo spend much of the novel trying to catch Julia, who has to flee from her various hiding places as she narrowly avoids capture and eventually ends up, by a secret tunnel, in the abandoned and seemingly haunted southern apartments of the Mazzini castle.

The introduction to the Oxford World's Classics edition notes that in this novel "Ann Radcliffe began to forge the unique mixture of the psychology of terror and poetic description that would make her the great exemplar of the Gothic novel, and the idol of the Romantics".

The novel explores the "cavernous landscapes and labyrinthine passages of Sicily's castles and convents to reveal the shameful secrets of its all-powerful aristocracy".