Booklist: Two years after the events of The Aeronaut’s Windlass (2015), Spire Albion is hovering on the brink of war with Spire Aurora, which has been field-testing a powerful weapon that leaves no witnesses as to what could cause such complete destruction. Captain Mad Grimm and the crew of the privateer airship Predator manage to rescue some survivors of an attack on Albion territory—a tribe of kittens. But the felines refuse to identify the threat unless provided with a new home, which will require negotiations with the cats of Spire Albion. As that agreement is worked out, Predator is assigned to accompany a diplomatic delegation to Spire Olympia, where a summit between competing Spires is being held, a conclave to determine future trade patterns and ascertain alliances for the coming war. Grimm himself has been tasked with preventing any confrontations between Alex Bayard, the delegation’s deputy, and Aurora’s deadliest duelist. If he fails, his friend will die, and Albion will be deprived of allies as war is declared. Butcher’s fans will delight in the new characters and alternate Spires while enjoying favorites from the first book and will be eager for the next episode in the action-packed Cinder Spires series.