In March 1584, the priest of Belamar de la Sierra, a small town in Aragon near the French border, is murdered in his own church. Most of the town's inhabitants are Moriscos, former Muslims who converted to Catholicism. Anxious to avert a violent backlash on the eve of a royal visit, magistrate Bernardo de Mendoza is appointed to investigate, and he is drawn into a complex and dangerous world in which fanaticism and state policy overlap. As the killings continue, Mendoza's investigation is overshadowed by a looming civil war.