Muman in the mid-seventh century. The respected scholar Dacán has been murdered while visiting the remote abbey of Ros Ailithir. Because he belonged to the neighbouring kingdom of Laigin, his death is used to demand an indemnity that could lead to war. The dying king of Muman sends Fidelma and the warrior Cass to establish who killed him before political negotiations collapse.
At the abbey, the scholar's work, his interest in local children and the ambitions of rival kingdoms prove inseparable. Fidelma must reconstruct Dacán's purpose in travelling to Ros Ailithir and determine who benefits from presenting an individual murder as an act of state aggression.