Ireland, AD 666. An attempt on King Colgú's life directs Fidelma to the great abbey of Imleach, where an elderly monk has disappeared and the revered relics of St Ailbe have vanished from his care. Blood in the monk's chamber suggests violence, but neither a body nor a clear route of escape can be found.
Because the relics are both sacred objects and symbols of Muman's authority, their loss carries political consequences. Fidelma and Eadulf investigate the abbey's divided community and the movements of visiting nobles, uncovering how the disappearance is connected to the attack on the king and to a conspiracy reaching beyond the monastery.