The Holy Land in the year 1193. Guillaume de Born, an unscrupulous Templar Knight on a secret mission to meet with the Assassins, acquires in Jerusalem what he believes to be the holiest relic of Christianity: the fabled Ark of the Covenant. On his way back to the port city of Acre, he is ambushed by his Templar brothers. They rob him of the treasure and leave him badly wounded in the mountains of Galilee. Deeply humiliated, he swears revenge. With the help of a young Muslim man, an unconventional Jewish woman and two daring Christian knights, he sets out to reclaim the sacred relic from the powerful Order. But the precious artefact is now in an impregnable Templar fortress, guarded by a ruthless enemy…