The Edge Chronicles 7: The Last of the Sky Pirates - First Book of Rook

Rook Barkwater lives in the network of sewer-chambers beneath Undertown, the bustling main city of the Edgeworld. He dreams of becoming a librarian knight - one of those sent out to explore the mysteries of their world. Somewhere out there lie the secrets of the past - including the lost floating city of Sanctaphrax - and hope for a future free from the fear of tyranny. When his chance comes, Rook breaks all the rules and sets out on a journey to the Free Glades.
His luck and determination lead him from one peril to another until he encounters a mysterious character - the last sky pirate - and is thrust into an extraordinary adventure. The Last of the Sky Pirates is the first book of the Rook Saga - third trilogy in The Edge Chronicles, the internationally best-selling fantasy series, which has featured on the UK and the New York Times best-seller lists and sold more than 3 million copies.
There are now 13 titles and four trilogies in the series, but each book is a stand-alone adventure, so you can read The Edge Chronicles in any order you choose.