Lucius Falerius is dead, and Rome in its entirety mourns the passing of its most powerful senator. It falls to his young son Marcellus to carry out his father's legacy and restore the rights promised to the defeated Sicilian slaves, yet there are those who will not see the honour of Rome compromised and the slaves assuaged.

On the Roman border provinces there is also trouble, and the legions move north to neutralize the threat posed by the Celts. The confederation of Celtic tribes is united under one chieftain, the formidable and unpredictable Brennos, but a plot is being crafted to see him dead and the confederation broken. For Brennos, the treachery comes from within his own family, for which he will exact a brutal and bloody revenge.

Meanwhile Aquila, accompanied by his 'nephew,' Fabius, finds himself under the command of a young tribune who bears the same name as the man responsible for the death of his old friend and mentor. And still there remains the question of the eagle charm he wears around his neck-the only clue as to his real identity.