Macro and Cato now find themselves members of the elite Praetorian Guard, charged with defending the emperor himself against harm. Yet, they rapidly find that the Guard is riddled with conspiracies aimed at bringing the ageing emperor Claudius down, and raising either of his two sons, one by birth, Britannicus, the other by adoption, Nero, to the purple. Needless to say, the two centurions manage to find themselves in the thick of the action. In the background is the Machiavellian figure of Narcissus, well known to both legionnaires, and also his rival for control of the emperor, Pallas.