Children of the flying city

"Brought to the flying city of Highgate when he was only five years old, orphan Milo Quick has never known another home. Now almost thirteen, Milo survives one daredevil grift at a time, relying only on his wit, speed, and best friends Jules and Dagda. A massive armada has surrounded Highgate's crumbling armaments. Because behind locked doors--in opulent parlors and pneumatic forests and a master toymaker's workshop--the once-great flying city protects a powerful secret, hidden away for centuries. A secret that's about to ignite a war. One small airship, the Halcyon, has slipped through the ominous blockade on a mission to collect Milo--and the rich bounty on his head--before the fighting begins. But the members of the Halcyon's misfit crew aren't the only ones chasing Milo Quick"--From the publisher's web site.