In January of 668 A.D., Fidelma of Cashel - sister to the king of Muman, advocate of the Brehon law courts and religieuse in the Celtic Church - is called to investigate the brutal murder of Abbess Faife and the mysterious disappearance of six young female religieuse while away on a short pilgramage away from their abbey. But when Fidelma and her husband, Eadulf, arrive, they are confronted with another violent murder under mysterious circumstances...