1307. Lothar de Thaon strives for excellence in a career with the Templar Knights – until he meets Thera, a young German woman returning from pilgrimage to the Holy Lands. Her beauty and sultry ways turns his head and captures his imagination despite his devotion to the Order and vows of chastity. Their shared passage on a ship to Southern France shapes their destiny and starts them down a road no one imagined. Lothar reports for duty at Avignon, where politics and greed inside the church hierarchy casts shadows over his chosen way of life.
His loyalty to the Order and his brother monks causes his banishment to a remote monastery in Normandy. Thera and her family return to a Germany in chaos, and find themselves caught up in the turmoil of two warring brothers fighting for the throne of their dead father, King Chlodwig. Before the summer is out, intrigue, betrayal and corruption send both of them fleeing through the towns, villages and forests of West Europe. Staying one step ahead of assassins, they find themselves in a desperate search for something more valuable than the Holy Grail.