Judith Perle, the recently-widowed wife of a rich merchant becomes the object of interest for the men of Shrewsbury. She gives her house to the abbey, in exchange for the nominal rent of one rose annually from the rose bush in its garden. But then one of Cadfael's associates, Brother Eluric, is murdered, after he is assigned the duty of picking and delivering the rose. And then one of her suitors is also murdered.

Popular local priest, Father Adam, has died, and is replaced by the strict, even heartless, Father Ailnoth. A young girl, Eleanor, comes to Cadfael asking him to give her confession. When he says he cannot, she reluctantly goes to Father Ailnoth, who refuses, and hounds her out of the church. The next day she is found drowned in the mill-stream, an apparent suicide, but so is Father Ailnoth, but his death is definitely murder. Abbot Radulfus charges Cadfael with investigating the deaths, before they reach the attention of King Stephen, in case doubts as to the town and church's loyalty to him cause unwanted attentions from his supporters, and drags Shrewsbury into the civil war. But it may already be too late.