To the good folk of late-Victorian Ancaster, the ancient figures of angels carved on the cathedral tower are benevolent guardians. However, the stubborn, autocratic Dean Girdlestone sees them as idols and orders their destruction. Festering resentments come to the surface, fed by the primitive anger of Josiah Solomon, Clerk of the Works. On the night of the Ancaster Revel, the Dean's murdered body is discovered, and suspicion falls on his bitter lifelong rival, the genial but unstable Prebendary Nicholas Arkwright. Haunted by frightful dreams, Arkwright confesses, but it takes the differing skills of the rural detective Inspector Jakson and Sergent Bottomley to uncover the brutal truth behind Girdelstone's murder, and to reveal the Ancaster Demons for what they really are.