In the winter of 1271, death stalks the corridors of Wynethorpe Castle on the Welsh border. When the Grim Reaper touches the beloved grandson of the castle lord, Baron Adam sends for his daughter, Prioress Eleanor of Tyndal, and her subinfirmarian, Sister Anne, to save the child with their prayers and healing talents. Escorting them to the remote fortress is Brother Thomas, an unwilling monk fighting his private demons. Soon after the trio arrives, an important guest is murdered. The prioress' brother, bloody dagger in hand, stands over the corpse. All others may believe in his guilt, but Eleanor is convinced her brother is innocent.