Since time immemorial, the Spiers have been a haven for humanity, towering miles above the fog that shrouds the surface of the world. Within their halls, aristocratic Houses have ruled for generations, making wondrous scientific discoveries, forging trade alliances, and building a fleet of airships to keep the peace. Grimm is the captain of the merchant ship Predator. Loyal to the Albion Spire, he sided with it in the Cold War with the Aurora Spire, disrupting the enemy's shipping lines by attacking their cargo ships. But when the Predator, after being damaged in battle, loses the ability to fly, Grimm receives an offer from the Spire of Albion - to join the team on a dangerous mission in exchange for the full restoration of the Predator. Having become involved in such a dangerous adventure, Grimm learns that the conflict between The spiers are only a harbinger of trouble to come. The ancient enemy of humanity, silent for more than ten thousand years, began to stir again. And now death itself will follow in his wake...