Enemies of the Empire — Rosemary Rowe

A three-day journey to the forested outskirts of the Empire is the last thing Libertus wants to make. Not only are there wolves and bears, but Celtic rebels may well regard the lone coach as fair game. But when Marcus Septimus asks Libertus to join him on official business, he knows he can't refuse his benevolent patron. En route to the garrison town of Isca, they stop at Venta: a simmering cauldron of social unrest where the Silures tribe, loyal to the memory of former chief Caractacus, seethes under Roman occupation. In the busy market square, Libertus is shocked by the glimpse of a familiar face. His pursuit of the figure leads him down a treacherous path and, before he knows it, into a murky world of racketeering, treason, and murder.