The story is part political intrigue, part coming of age story. In 1856, the spare heir of the Imperial Roman empire, Constantine, is sent to join the Imperial Army’s newest legion, the Germaina XIII, and ends up leading the 13th cohort (of the 13th legion) through basic training, which has our other main character, the former factory worker Julius, as a member. Their unit is singled out for special duties in the roman army working behind enemy lines. In Brittenburg, a rebellion threatens to topple the empire and plans to kill the emperor. The older heir to the throne is killed back in Rome, although the Emperor escapes. Constantine is recalled to protect his safety, arriving in Brittenburg just in time for the instigators to strike, as open revolt strikes the city with assistance from an old enemy. The new legion is forced to quell the city revolt, rescue their tribune, and save a critical factory city from the deprivations of enemy and rebel forces.