In the ruins of a post-nuclear America, where civilization clings to existence in scattered safe zones, a mysterious gate appears in Boston. Out of it march legions of what appear to be Roman soldiers, claiming the irradiated wasteland for their empire. But they soon discover that the survivors of the Great War possess weapons far beyond their comprehension, and the wasteland itself is a deadly enemy. As two worlds collide, will the remnants of the United States military find a path to salvation, or will they unleash a new kind of terror upon a world unprepared for the apocalypse?