Rome is in peril. The old order is changing. Centurion Aurelius Castus has been summoned back from Britain to find himself caught up in a treasonous conspiracy threatening to bring down the Emperor Constantine. Rewarded for saving the emperor's life, Castus is promoted to the elite imperial bodyguard: the swords around the throne. But he soon discovers the court to be as dangerous as the battlefield. Behind the gilded facade of empire lurks a nest of traitors and one relentless enemy.