The story is set in 367 AD when the Roman Empire is struggling to repel the Irish invaders in the northern provinces of Britannia. The main character, Marius, is a member of the Corinium council who is transporting an Alamanni slave/gladiator to the emperor. Traveling with them is a priest named Barnabas and the slave's sister Freia.
They are attacked by a band of Irish and barely escape with their lives. The Irish capture Freia and take her away. The group then sets out to get her back.
When they reach the Irish stronghold they learn that the forces are led by a rogue Roman who was responsible for the death of Marius' parents.
The story moved along rapidly and kept my interest. I liked the characters and that there was some humor sprinkled throughout the story.