Baron Herbert returns from the Crusades and falls into a deep melancholy. When his sons begin to die in strange accidents, people begin to wonder if the baron has been cursed by God. Herbert asks his friend Sir Hugh of Wynethorpe to bring him spiritual and secular healers, so Sir Hugh invites his sister, Prioress Eleanor of Tyndal Priory, and a respected physician named Master Gamel to the baron's castle. The prioress brings along her healer, Sister Anne, as well as Brother Thomas, a man Sir Hugh despises. As the bodies begin to pile up, Prioress Eleanor and Sir Hugh must discover the truth behind the mysterious deaths before it's too late.