A single death could plunge the Empire into chaos.Silus, member of Emperor Caracalla's elite assassins, the Arcani, is dispatched to Numidia. Rumours of assassination plots against Marcellus, the Emperor's closest aide, are rife. Silus must stop them. But the forces arrayed against the Arcani are now as powerful as they are clandestine.Inducted into the Emperor's bodyguard, his Lions, Silus soon discovers secrets that should have stayed hidden. And as the Emperor becomes ever more reckless in battle, Silus unearths a conspiracy that runs deeper than his worst nightmares.It's not clear who is a friend, and who an enemy. Yet come what may Silus must keep the Emperor alive or - yet again - watch the ones he loves die.