Cadfael's young novice monk, Brother Oswin, is found in a dreadful state and babbling about a woman. Then a missing nun is found raped, murdered and locked in the ice of a frozen stream, and Brother Oswin is accused of the crime. Cadfael traces the nun's friend, Ermina Hugonin, and he hopes to prove that Brother Oswin is innocent by finding the true killer.

An important priest is found murdered, and the finger of suspicion points to a new monk at Shrewsbury Abbey. Brother Cadfael investigates the killing and uncovers a tangled web of dishonesty and nepotism. Meanwhile, a civil war is raging around England and is piling pressures on the Abbot.

A group of monks from Shrewsbury Abbey travel into Wales to recover the bones of Saint Winifred. When they try to bribe the Welsh, they find themselves at odds with the locals, and when a Welsh landowner is found murdered the visiting English monks are looked on as the prime suspects. They turn to Cadfael to find the true killer and to save themselves.