Christmas, 1510; the Burren, West coast of Ireland. Mara, Brehon (investigating judge) of the Burren, has accepted the offer of marriage made by King Turlough Donn O'Brien, ruler of that tiny kingdom of stony land and terraced mountains on the shores of the Atlantic Ocean. The marriage is planned to take place at the Cistercian Abbey on Christmas Day. But, on the eve of the marriage festivities, a man kneeling in prayer beside the tomb of an ancestor in the abbey church is violently battered to death. Who could have planned to kill the king? Or was it his cousin, Mahon O'Brien, who was the planned victim? And what part did the abbot, cousin to one man, and brother to the other, play in the tragedy? A heavy fall of snow has cut off the abbey from the outside world; the assassin must still be within the cloister walls. Mara must act quickly before a second death occurs.