Pavement-maker Libertus, a former slave who is now a Roman citizen, is not entirely surprised to witness a stabbing near the chariot race ground in bustling Corinium (modern Cirencester). Luckily the victim, the wealthy decurion Quintus Ulpius, has a personal physician on hand and tragedy is averted. Commanded by his patron Marcus Septimus to investigate the attack, Libertus arrives at Quintus's mansion only moments before the decurion is knifed again, this time fatally. When one of Quintus's enemies is found with bloodstains on his toga, for Marcus the case is closed. But Libertus is not at all convinced the solution is that simple. When a second body is found, he knows he must act fast before other lives are threatened - including his own.