Sister Fidelma & her companion Brother Eadulf are on their way to visit the new Archbishop of Canterbury when their ship is blown off course & they land on the coast of the Welsh kingdom of Dyfed. They are given hospitality by King Gwlyddien & Abbot Tryffin of the Abbey of Dewi Sant & are asked if they would help to solve the mystery of how the entire monastic community of the Abbey including the King's eldest son could vanish into thin air. It's not long before the trail leads to deaths & treachery in high places & Fidelma & Eadulf are faced with a sinister & baffling puzzle.