Aurelius Ambrosius is the rightful king of Britannia. He has built up an army like the Roman legions of old, but he knows it is not enough. If he is to win the support of his fellow Britons he must find the Sword of Albion to prove his right to the kingship. But others are looking for that sword, among them, the "proud tyrant", Vortigern. Aurelius goes on a perilous quest through crumbling Roman cities, the rugged Pennines and Angle-occupied territory, while Vortigern tries everything to stop him, including making a fake sword, but while these two Britons are battling for supremacy, the Angles and Saxons, led by Hengest, are invading from the North Sea.