When the simmering conflict between Rome and Persia threatens to reignite 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, has fought long and hard for Rome. When the summons comes to command an army once more, he obeys with a heavy heart. But is he still the fearsome fighting machine of old? As tragedy strikes the imperial household, Castus must race to defend the last bulwark standing against the might of Persia. Castus knows that the fight ahead will be the fiercest he has ever known, and will very probably be his last.