Ellis Peters' fourth Brother Cadfael mystery is set in the summer of 1139, in a Shrewsbury still recovering from the siege of town and castle by the army of King Stephen the previous summer. To speed the rebuilding of its defences, the townsfolk are eager for financial help from the abbey of Saint Peter and Saint Paul, which, being located just outside the town, came through the episode of the siege without harm. With the lucrative annual three-day St. Peter's fair fast approaching, the burghers of the town are anxious to secure a share of its profits - normally given over entirely to the abbey. The new abbot, however, is far from anxious to set a dangerous precedent by ceding away the abbey's dues.