It is the year of Our Lord's grace 1431, and the nuns of England's St. Frideswide sweetly chant their Paternosters behind gracious, trellised walls. But their quiet lives are shattered by the unwelcome visit of the hard-drinking, blaspheming dowager Lady Ermentrude, with her retinue of lusty maids and men, baying hounds, and even a pet monkey in tow. The lady demands wine, a feast, and her niece, the frail and saintly novice Thomasine. What she gets is her own strange and sudden death. Sister Frevisse, hosteler of the priory and amateur sleuth, fears murder. The most likely suspect is pious Thomasine . . . but Frevisse alone detects a clever web spun to entangle an innocent nun in the most unholy of passions--and the deadliest of deeds.