It is AD 42, and Quintus Licinius Cato has just arrived in Germany as a new recruit to the Second Legion, the toughest in the Roman army. If adjusting to the rigours of military life isn't difficult enough for the bookish young man, he also has to contend with the disgust of his colleagues when, because of his imperial connections, he is appointed a rank above them. As second-in-command to Macro, the fearless, battle-scarred centurion who leads them, Cato has more to prove than most in the adventures that lie ahead.

Then the men discover that the army's next campaign will take them to a land of unparalleled barbarity - Britain. After the long march west, Cato and Macro undertake a special mission that will thrust them headlong into a conspiracy that threatens to topple the Emperor himself...