Sir William the Marshal, legend in his own time, has promised to go on crusade, a vow made to his Young King as he lay dying. But when the Oliphant, legendary war horn of Roland, is stolen by the lethal Assassins, he’s charged with returning the relic in order to stop the very thing he’d vowed to undertake—a crusade; this one engineered by the thieves.

With his small band of trusted companions—Sir Baldwin, his tourney compatriot; Eustace, his squire; and Henrik, the giant Norseman—William sets out to take back the relic. But treachery abounds, and when William loses two of his companions, he discovers an unlikely ally—Da’ud, an Assassin himself, bent on taking the Oliphant from the heretic faction that has stolen it. The three fight their way across land, sea, and desert, only to find themselves facing an army…and the Oliphant within their grasp.