A potter's wife dies suddenly, and he gives up his old life to enter the Abbey, but the other monks suspect him of having killed his wife. As Cadfael investigates the death he finds a curious web of jealousy, infidelity and suicide.

The dead body of an elderly man is found hidden in a sack at the Abbey, and Cadfael believes he was murdered. The principal suspects are a group of pilgrims, who include two known thieves. Cadfael locks them up, in a bid to draw out the killer.

Dalny, a beautiful slave girl, is abducted from the Abbey—and the relics of St. Winifred are also spirited away, apparently by the same thief. Cadfael is commissioned to find them both.