While Cerdig the Saxon chief leads his warriors further and further into Celtic territory, Arthur tricks the warring Celtic chieftains into banding together to repel the invaders.
Two orphaned Saxon children drift into Arthur's village, and Kai, as the only Saxon amongst Arthur's men, is ordered to return them to their home. All goes well until the children innocently tell the villagers who Kai is.
Arthur has to deal with two cousins who, instead of guarding their villages as ordered, spend their time fighting over their inheritance, thus allowing the Saxons to attack.
Newly converted to Christianity, Rolf uses the forgiveness offered by the new religion to continue indulging his violent excesses. Llud tries some old Mithraic penances to try to change his ways.
On his way to acquire weapons from a weapons-maker in another village, Kai helps a Saxon woman whose husband, unbeknown to her, has been captured by the very man Kai is going to see.
With the chiefs banded together under Arthur's leadership, the Celts head for battle with the Saxons. Complications occur when Llud accidentally kills Mark of Cornwall's lieutenant.
The son of a man Arthur killed in battle seeks him out to learn how to fight, ostensibly to guard his people, in reality to take revenge. Part way through his training he realises Arthur is the man he wants to kill.
When Rolf, the preacher, arrives at a village, he causes trouble for Arthur because he preaches against war and fighting. Arthur is soon running out of warriors. The aggressive Mark of Cornwall is trying to solve the problem through force.
Arthur and Kai arrive at a village, whereupon Kai finds an old flame, Goda. The two then decided to get married. However, several of the villagers are plotting against Arthur.
Arthur and Kai arrive at a village where the Saxons have attacked. All the men in the village have been enslaved and sent to the mines. Kai then takes Arthur and Llud prisoner to instigate a revolt in the slaves.
A Saxon ex-gladiator kidnaps two children of the wandering herbalist Wood People tribe, and will only return them in exchange for Arthur. It takes both Arthur's own warriors and the herbalists to save the day.
Arthur tricks Mark of Cornwall into travelling into Saxon territory with him and a small band of warriors, all disguised as Saxons, in order to retrieve a great treasure. But the treasure is not quite what Mark has been led to believe.
