"We - the Tenabrans - we stood before the Dark. We were among the first. Tell your children that. And picture this: the castle of Ys, the outer faces of its walls washed with golden fire. Flame gushed out of the sluices to light and to burn the Dark, and the night was wicked with flying steel and thick with magic..." A sword maiden, a small Tenebran force and a young man called Will de Parkin: together they must defeat the unnatural armies of the Dark, and save the castle of Ys.