The brilliant first saga in a sequence of novels set at the end of the Roman Empire, during the reign of the Emperor Constantine. Centurion Aurelius Castus - once a soldier in the elite legions of the Danube - believes his glory days are over, as he finds himself in the cold, grey wastes of northern Britain, battling to protect an empire in decline. When the king of the Picts dies in mysterious circumstances, Castus is selected to guard the Roman envoy sent to negotiate with the barbarians beyond Hadrian's Wall. Here he will face the supreme challenge of command, in a mission riven with bloodshed and treachery, that tests his honour to the limit.