I still can't believe I've put the bastard away for good!' Petro muttered. Petronius Longus, captain of the Aventine watch and Falco's oldest friend, has finally nailed on of Rome's top criminals. Under Roman law citizens are not imprisoned but are allowed 'time to depart' into exile outside the Empire. One dark and gloomy dawn Petro and Falcoput the evit Balbinus aboard ship. But soon after, an outbreak of robbery and murder suggest a new criminal ring has moved into Balbinus' territory. Petro and Falco must descend into the underworld of Vespasian's Rome to investigate...