High in the mountains of the Lake District is a secret valley where the Vikings have their last strongholdtheir Shield Ring. The Normans seek to crush this group of Northmen and to bring all of England under their control. They build a castle in Carlisle and send an army north. Meanwhile, the Northmen lamb and harvest as though life were normal, but Ari Knudson sharpens Wave-flame and the Jarl prepares his War Host. Two youths of the villageFrytha, a Saxon girl who fled to the valley when the Normans burned her home, and Bjorn, the foster-son of the old harpermake ready, too. As the Norman's approach the secret valley, the Northmen recruit able bodies, and Bjorn volunteers to enter the Norman camp as a spy. Frytha knows Bjorn's deepest fear: that if he is captured, he will fall to Norman torture and reveal the location of the Shield Ring.