The year is AD 255. The Roman Imperium is stretched to breaking point, its authority and might challenged along every border. The greatest threat lies in Persia to the east, where the massing forces of the Sassanid Empire loom with fiery menace. There the isolated Roman citadel of Arete awaits inevitable invasion. One man is sent to marshal the defences and shore up the crumbling walls. A man whose name itself means war: Ballista. Alone, Ballista is called to muster the forces and the courage to stand first and to stand hard against the greatest enemy ever to confront the Imperium. This is an epic of empire, of heroes, of treachery, of courage, and, most of all, a story of brutal, bloody warfare.