In 7th century Rome, the man due to be the next archbishop of Canterbury is strangled while awaiting his consecration. An Irish brother is a suspect and the motive is believed to be political. Sister Fidelma of the Celtic Church goes to work.

Summer, AD 672. Princess Gelgeis has arrived in Cashel with her personal bodyguard, a troop of female warriors called the Daughters of the Storm. When one of them is found slain next to the sleeping chamber of the newly married king and queen and, a short time later, the stewardess of the royal house is poisoned, questions are raised as to everyone's safety. Fidelma and Eadulf must first explain the 'locked room' mystery of how the attack took place...