Anno Domini 1190-1191

Lord Robert de Borron and his companions continue their dangerous adventure. It will transport them from twelfth-century Iberia to an abbey in England.

In the first century A D, Saint Joseph flees Jerusalem and departs on a perilous sea voyage to the mysterious isle called Avalon. A serial killer stalks him and his family.

Lord Robert is tempted by a widowed Iberian princess, who delays him from his holy quest. A former dead enemy returns with the unseen Hashishiyya (secret sect of assassins) to bring death and destruction to Lord Robert's companions. Both a Muslim and a Jewish scholar help Lord Robert use the mystical Kabbalah to seek manuscripts written by the forgotten disciple.

The demonic machinations of Cardinal Folquet and his knights thwart Lord Robert's progress, but a bull-fighting dog joins Lord Robert and his warrior friends to stop the cardinal and the assassins. What secrets lie hidden on the Isle of Glass? Who put them there?

Finally, Saint Joseph reaches the ancient Druid college of Avalon. He knows a secret that will shock the Christian faith. However, Lord Robert is sworn to secrecy until the next grail seeker comes.