Over four hundred years before the birth of Christ, the island of Ériu is a patchwork of feuding kingdoms, wide plains, and impassable bogs. Battle, intrigue, betrayals, and courage are part of life for the Celts who call Ériu home, while from their underground halls the mysterious Aes Sidhe seduce brave warriors, turning men in to kings and binding them with fearsome geis. Conall Mac Gabhann is content with his apprenticeship to the local blacksmith. Content, that is, until his family is slaughtered in their home. Two men share responsibility for the massacre: a mad Irish king and a dissolute Roman. Conall will have his vengeance on both, or die in the attempt. Accompanied by his childhood friend Brion ó Cathasaigh and the veteran warrior Fearghal ó Maoilriain, Conall's hunt takes him northward through unfriendly kingdoms and treacherous bogs to a confrontation beyond the ancient earthworks of the Black Pig's Dyke. Along the way, Conall will gather an army, and come to the attention of the Aes Sidhe. An apprentice blacksmith could become a king with their help—if he so desires.