Roman senator Valerius Aquila sends his son Marcus with a letter from the emperor to the commander of the Sixth Legion stationed in Britain. But when the young man arrives at the scene, he is immediately... arrested. It turns out that while Aquila Jr. was getting from the capital to the distant western colony, his father had already been executed on charges of treason. Now the same fate awaits Mark. However, with the help of old friends of his father, who once served in the same legion, he manages to escape and hide from his pursuers. For the young man, the struggle for survival begins. Under a false name, he joins the Tungrian cohort, where he finds a new life and reliable fighting friends...