Sister Fidelma hurriedly returns from her distant pilgrimage as soon as she learns that her loyal companion, Saxon Brother Adolphus, has been imprisoned in the capital of the enemy kingdom of Lagin, accused of murder.
Arriving at the Abbey of Fearn, Fidelma will clash with the formidable Abbess Faither, who rules her community with an iron fist and has no doubt about Adolphus' guilt. Indeed, the evidence and testimonies against the Saxon monk seem overwhelming. But is it possible for an honest and kind man to have any connection to the rape and strangulation of a young girl?
Dismayed in the dark and gloomy atmosphere of the abbey, Fidelma has little time to discover the truth. The young king of Lagin has been persuaded by the Abbess to abandon the country's traditional laws and replace them with the "Penitentials," a system of justice inspired by the Church that comes from Rome. And as this harsh law requires "an eye for an eye," Adolphus is to be hanged the next morning...