Catherine's estranged younger sister, Agnes, has been promised in marriage to a German lord. Bitter about their religious differences, Agnes wants no part of Catherine or their father--except for the sizable dowry that he can provide. When Catherine and her father send Agnes off with her dowry and two knights in escort, they assume that they have seen the last of her. But soon one of the escorts returns with terrible news: Agnes' new husband appears to have been murdered, and Agnes, the prime suspect, is being held, accused of murder by poisoning, or even worse, witchcraft.
In spite of their differences, Catherine believes in Agnes' innocence, and knows that she must do everything she can to save her sister's life. But when Catherine and her brood travel to Germany to begin sleuthing in a dangerously anti-Semitic climate, it becomes clear that Catherine and her husband's long-dreamt-of life of peace remains in the distant future--if they live to see it.