Petronius Longus, captain of the Aventine watch and Falco’s oldest friend, has finally nailed one 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 night, Petronius and Falco put the evil Balbinus aboard ship. But soon after, an outbreak of robbery and murder suggest a new criminal ring has moved into Balbinus’ old territory. Petronis and Falco must descend into the shady underworld of Vespasian’s Rome to investigate.