Driven to become a brilliant soldier and now given command of a small fort in the southwest, Marcus bravely leads his troops during a siege. Commended by Rome for his bravery, yet discharged from the army because of his severe wounds, Marcus convalesces, demoralized, in the villa of his Uncle Aquila, a retired army man. When Marcus impulsively gets a young Briton’s life spared at a gladiatorial contest, Aquila buys the Briton, Esca, to be Marcus’ slave. Marcus is dismissive of Esca, who harbors a seething hatred of all things Roman. Yet Esca vows to serve the man who has saved his life.
Hearing a rumor that the Eagle has been seen in a tribal temple in the far north, Marcus is galvanized into action, and sets off with Esca across Hadrian’s Wall. But the highlands of Caledonia are a vast and savage wilderness, and Marcus must rely on his slave to navigate the region. When they encounter ex-Roman soldier Guern, Marcus realizes that the mystery of his father’s disappearance may well be linked to the secret of his own slave’s identity and loyalty – a secret all the more pressing when the two come face-to-face with the warriors of the fearsome Seal Prince.