Corus is a world of humans, but also of strange animals and supernatural creatures. It is a world of magical powers and of a few people who are Talented enough to use them. Alucius, the hero of the story, is one such person. In Legacies we saw how he grew from a Talented child on a lonely Nightsheep ranch in the Iron Valleys to a proficient soldier who used his wits and his Talent to become the first to escape military enslavement in the neighboring country of Madrien. Now captain of the Twenty-first Company, the youngest officer of his rank in the Militia, he must now face new challenges, both military and magical.

Corus has been fragmented since the collapse of its ancient magic-powered civilization. A would-be conqueror has somehow revived sorcerous creatures of legend to assist in his crusade to reunite the continent under his rule. The Iron Valleys are forced into an alliance with the Lord-Protector of Lanachrona, and the Twenty-first is dispatched to stand against the invaders. Neither the officers above him nor the men under him know it, but Alucius's Talent is their only hope for victory, or even survival.