In A.D. 644, a respected scholar of the Celtic Church is murdered during a visit to the Irish Kingdom of Muman. The kingdom's ruler summons Sister Fidelma to solve the brutal murder, but her time is limited. The victim, as it turns out, was a comrade of the arrogant King of Fearna, who threatens war over the suspicious death of his friend. But during her inquiries, Sister Fidelma comes to realize that there is more at hand than what appears, and finds her own life caught in the balance.