When an act of murder throws the western provinces into turmoil, Aurelius Castus is ordered to take command of the military forces on the Rhine. But he soon discovers that the frontier is a place where the boundaries between civilisation and barbarism have little meaning. At the very heart of the conflict are two boys. One is Emperor Constantine's young heir, Crispus. The other is Castus' own beloved son, Sabinus. Only Castus stands between them and men who would kill them.

When the simmering conflict between Rome and Persia threatens once again to ignite into open war, there is only one man the Emperor Constantine can trust to hold the eastern frontier. Aurelius Castus, retired general of the empire. When the summons comes to command an army once more, he obeys with a heavy heart. Is he still a fearsome fighting machine? Will his young, ambitious officers respect and follow a great soldier of former days? When tragedy strikes, Castus must race to defend the last bulwark standing against the might of Persia. 

The first novel in Simon Scarrow's bestselling Roman series. It is 42 AD, and Quintus Licinius Cato has just arrived in Germany as a new recruit to the Second Legion, the toughest in the Roman army. If adjusting to the rigours of military life isn't difficult enough for the bookish young man, he also has to contend with the disgust of his colleagues when, because of his imperial connections, he is appointed a rank above them.

The Roman Empire is on the brink of civil war. Only Maxentius, tyrant of Rome, stands between the emperor Constantine and supreme power in the west. Aurelius Castus, promoted from the ranks for valour, is now a tribune in Constantine's army. But as Constantine becomes increasingly devoted to Christianity, Castus is forced to ask himself whether he is backing the wrong man....

Rewarded for saving the emperor's life in battle, centurion Aurelius Castus is promoted to the Corps of Protectores, the elite imperial bodyguard, the swords around the throne. But he soon discovers the court to be just as hazardous as the battlefield; behind the gilded facade of empire, there are spiralling plots, murderous betrayals and dangerous seductions. And one relentless enemy.