Winter, AD 670. During a feast at Cashel, a religieux approaches King Colgú, cries out the name Liamuin and stabs him before the court. The attacker dies without explaining the accusation, leaving Fidelma to discover what event from the past could have inspired an attempt on her brother's life.
Her search follows a history deliberately excluded from royal memory and connects the assault to families who believe Cashel escaped responsibility for an old wrong. With Colgú's survival uncertain and further violence threatened, Fidelma must separate inherited grievance from present conspiracy and determine what true atonement would require.