Heresy, murder, and the contents of a mysterious treasure chest challenge Brother Cadfael—12th-century herbalist, sleuth, and sometime cupid—in his 16th chronicle.

In the summer of 1143, William of Lythwood arrives at the Benedictine Abbey of St. Peter and St. Paul, but it is not a joyous occasion—he's come back from his pilgrimage in a coffin. William's body is accompanied by his young attendant Elave, whose mission is to secure a burial place for his master on the abbey grounds. An already difficult task is complicated when Elave drunkenly expresses his heretical opinions, and capital charges are filed. When a violent death follows, Sheriff Hugh Beringar taps his friend Brother Cadfael for help.