July 2005. In the Pyrenees mountains near Carcassonne, Alice, a volunteer at an archaeological dig stumbles into a cave and makes a startling discovery-two crumbling skeletons, strange writings on the walls, and the pattern of a labyrinth; between the skeletons, a stone ring, and a small leather bag.
Eight hundred years earlier, on the eve of a brutal crusade to stamp out heresy that will rip apart southern France, Alais is given a ring and a mysterious book for safekeeping by her father as he leaves to fight the crusaders. The book, he says, contains the secret of the true Grail, and the ring, inscribed with a labyrinth, will identify a guardian of the Grail. As crusading armies led by Church potentates and nobles of northern France gather outside the city walls of Carcassonne, it will take great sacrifice to keep the secret of the labyrinth safe.
In the present, another woman sees the find as a means to the political power she craves; while a man who has great power will kill to destroy all traces of the discovery and everyone who stands in his way.