Ellis Peters: The Heretic's Apprentice

From the Publisher:
In the summer of 1143, William of Lythwood returns to Shrewsbury in a coffin, his pilgrimage at last at an end. William's young attendant, Elave, accompanies the body and sets out trying to secure a burial place on the grounds of the abbey of St. Peter and St. Paul, despite William's once having been reproved for "heretical views." .

Elave, too, has evidently, learned skepticism. After he drunkenly expresses heretical opinions, the mighty prelate Gerbert brings capital charges against him. The beautiful Fortunata, whom Elave adores, becomes a reluctant witness for the prosecution. .

When violent death follows, Brother Cadfael is once again called from his herbiary to the aid of his old friend Hugh Beringar, the sheriff. Cadfael's new task is twofold: there are charges of heresy to be rebutted, as well as a murder to be solved.

Ellis Peters: The Heretic's Apprentice. The Sixteenth Chronicle of Brother Cadfael. Warner Books, ISBN: 0446400009 (February, 1991), $6.99.