Growing up on a prosperous farm in Viking Norway, young Eyvind dreams of the day when he can become one of the Jarl's elite warriors, the Wolfskins. For him, there can be no more glorious existence.
But Eyvind's life is to follow an unexpected path. A vow made in childhood binds him in friendship to the strange, silent boy Somerled, for whom he feels both pity and admiration. It is a promise that is to shadow Eyvind all his days, stretching his loyalty to breaking point.
From the dark forests of his native land, Eyvind voyages far. In the western sea lies a mysterious realm of peaceful waterways and fertile grazing lands. But the Light Isles are more than they seem. Powerful forces dwell there, beings as old as the earth itself, spirits of ancestral wisdom.
The Norsemen bring chaotic change to this ancient realm, threatening the end of a culture which has existed in the isles since time before time. It is up to Nessa, keeper of the mysteries and kinswoman of the last great king of the Folk, to find a way for her people to survive against daunting odds. For Eyvind, the choice is a stark one: to honour an oath made in blood or to act as heart and conscience demand. For either, the price may be death.