The Hunter's Apprentice - The Ravencrest Chronicles, #2

Miles grew up as a sparrow, an orphan in Seahaven and one of master thief Gareth's tiny spies. The coastal city has always been his home and the streets where he laid his head. Now he's learning the shadow craft from his mentor. But when Miles uncovers secrets behind a sinister plot, he discovers there are deadlier things awaiting in the shadows than he could have imagined. And with Gareth's help, he must learn to hunt them down.