An aged monk and the priceless relics of St. Ailbe disappear one night from the Abbey of Imleach. The missing monk is a matter of great concern for the abbey, but the missing relics are a disaster for the entire kingdom. The relics are a major political symbol of Muman, one of the seventh-century Irish kingdoms, and their disappearance threatens to disrupt continued peace and stability. Sister Fidelma, an advocate of the Brehon courts and sister of the king, is asked to investigate and recover the missing items. But dark forces are at work and they will stop at nothing to achieve their sinister aims.