The Last Of The Sky Pirates by Chris Riddell and Paul Stewart (2009, Paperback, Reprint)

The newest paperback installment in the exciting Edge Chronicles!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. When his chance comes, Rook grabs it! Breaking all the rules, he sets out on a journey to the Free Glades and beyond. His luck and determination lead him from one peril to another until, buried in the heart of the Deepwoods, Rook encounters a mysterious character and is thrust into a bold adventure that dares to challenge the might of the Guardians of the Night. . . .From the Trade Paperback edition.