Imperial agent Gaius Flaminius Drusus is working undercover as a tribune in the Praetorian Guard. His remit is to investigate the death of Rufinus Crassus, the senator who died mysteriously after his assassination attempt on the emperor Hadrian. Commissary Centurion Probus thinks the senator was murdered by his fellow conspirators to keep him silent. Identifying the murderer takes them only a short time, but the investigation becomes more complicated...