It's AD 188, and the wild, forested outskirts of the Empire is the last place Libertus, freedman and pavement-maker, wants to visit. But he'd rather face a wolf or bear than an angry patron, so he agrees to accompany Marcus Septimus to the garrison town of Isca (now Caerleon in South Wales). Pausing at Venta, the two men realise they've stepped into a simmering cauldron of social unrest, where the Silures tribe, loyal to former chief Caractacus, seethes under Roman occupation. When Libertus spots a familiar figure, who seems desperate not to be recognised, curiosity gets the better of him. But his pursuit leads him down a dangerous path and into a murky world of racketeering, treason and murder...