The city of Rome in AD 50 is a dangerous place. Treachery lurks on every corner, and a shadowy Republican movement, 'the Liberators', has spread its tentacles wide. It is feared that the heart of the latest plot lies in the ranks of the Praetorian Guard. Uncertain of whom he can trust, the Imperial Secretary Narcissus summons to Rome two courageous men guaranteed to be loyal to the grave: army veterans Prefect Cato and Centurion Macro. Tasked with infiltrating the Guard, Cato and Macro face a daunting test to win the trust of their fellow soldiers. No sooner have they begun to unearth the details of the Liberators' devious plan than disaster strikes: an old enemy who could identify them, with deadly consequences, makes an unexpected appearance.