Cadfael is on a double murder hunt following the deaths of a pregnant girl and the priest who refused to take her confession.

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.

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.