The Roman Empire is on the brink of civil war. Only Maxentius, tyrant of Rome, stands between the emperor Constantine and supreme power in the west. Aurelius Castus, promoted from the ranks for valour and loyalty, is now a tribune in Constantine's army. But great honour brings new challenges: Castus is tormented by suspicions that his aristocratic wife, the mother of his child, has been unfaithful. And as Constantine becomes increasingly devoted to Christianity, Castus is forced to ask himself whether he is backing the wrong man. All know that the coming war will decide the fate of empire. But Castus's own battle will carry him much further - into the shadowy realms of treachery at the heart of Rome itself. The third book in the brilliant Twilight of Empire.