While Brother Cadfael has bent Abbey rules, he has never broken his monastic vows—until now. Word has come to Shrewsbury of a treacherous act that has left 30 of Empress Maud's knights imprisoned during England's dynastic war between two grandchildren of William the Conqueror. All have been ransomed except Cadfael's secret son, Olivier. Conceived in Cadfael's soldiering youth and unaware of his father's identity, Olivier will die if he is not freed. Cadfael is determined to find him but must leave the monastery without his abbot's blessing.