In 670 A.D. Fidelma of Cashel is asked to act as an advisor to the Irish delegation to a church council hostile to the Celtic Church. In an abbey in Burgundy, Bishop Leodegar of Autun has assembled church leaders from all over western Europe€"an assembly which soon descends into chaos. That night, one of the delegates is found murdered, his skull crushed and Fidelma and her companion, Brother Eadulf, are suddenly in the midst of a murder investigation involving some of the most power religious leaders. Between the autocratic Bishop Leodegar and the malignant abbess, Mother Audofleda, a web of sinister intrigue soon spreads. The theft of a priceless reliquary box, the disap pear ance of women and children and rumours of a slave trade make this one of the most sinister and deadly puzzles that Fidelma and Eadulf have ever faced.