Jim Butcher is one of the top-selling fantasy writers on the market, and his Harry Dresden books are perhaps the most popular urban fantasy titles of all time. But many of Butcher’s legions of fans are unaware of his six-volume epic fantasy series Codex Alera, published between 2004 and 2009. In September Butcher will try his hand at epic fantasy again, with the first volume of a new steampunk series set in a world of noble families, steam-powered technology, and magic-wielding warriors, which the author describes as a little like “League of Extraordinary Gentlemen meets Sherlock meets Hornblower.” The Aeronaut’s Windlass, the first volume of The Cinder Spires, goes on sale September 29 from Roc.

Since time immemorial, the Spires have sheltered humanity, towering for miles over the mist-shrouded surface of the world. Within their halls, aristocratic houses have ruled for generations, developing scientific marvels, fostering trade alliances, and building fleets of airships to keep the peace.

Captain Grimm commands the merchant ship, Predator. Fiercely loyal to Spire Albion, he has taken their side in the cold war with Spire Aurora, disrupting the enemy’s shipping lines by attacking their cargo vessels. But when the Predator is severely damaged in combat, leaving captain and crew grounded, Grimm is offered a proposition from the Spirearch of Albion — to join a team of agents on a vital mission in exchange for fully restoring Predator to its fighting glory.

And even as Grimm undertakes this dangerous task, he will learn that the conflict between the Spires is merely a premonition of things to come. Humanity’s ancient enemy, silent for more than ten thousand years, has begun to stir once more. And death will follow in its wake…

The Aeronaut’s Windlass, Volume One of The Cinder Spires, will be published by Roc on September 29, 2015. It is 640 pages, priced at $27.95 in hardcover and $13.99 for the digital edition. The cover is by Chris McGrath.