The letter also contains another message, written in code, warning the legate that someone on his staff has been implicated in Scribonianus's failed coup attempt, and the Emperor has sent an unnamed Imperial agent to identify the person.

Cato, the son of a freed slave at the Imperial Palace, is unused to the harsh life of a Roman Legion, and is resented by his fellow recruits for being promoted ahead of them.

When a Roman tax collector is mutilated by the chief of a local German town, Vespasian sends the Third Cohort, under tribune Vitellius, which includes Macro's Sixth Century.

At Cato's suggestion, the embattled legionaries set fire to the attacking Germans' rudimentary battering ram, but the flames unfortunately spread to the gate, then the rest of the village, forcing the century to fall back from the walls.

Macro later nominates Cato for a Grass Crown, and, to their shared embarrassment, both are invited to dine at Vespasian's house after the Cohort returns to base.

On the one hand, he stages a comic performance in Gesoriacum's amphitheatre, pretending to challenge the legionaries to a fight, and provoking amused cries of "Io Saturnalia!"

In private conference with Vespasian, Narcissus orders him to detail a small detachment of men to infiltrate British territory and retrieve the lost pay chest.

He is repulsed and escapes on his horse, inadvertently discovering a British force led by the warlord Togodumnus, setting up an ambush along the legion's line of march.