The land of Gable-renowned for its birds, revered for its legends and secrets-is home to the grandest castle in the known world. Inside this castle, in a narrow cell atop the dungeon tower, the legendary Marauder known as James Kestrel awaits his hanging. Amidst the anticipation and speculation surrounding his execution, rumors are spreading that the Marauders will come out of hiding for the first time in seven years to free Kestrel in order to find the Caelum Flute, an instrument with the power to control the birds, and therefore the world. But only a wandering giant and a slave girl masquerading as an innkeeper know the truth. And everything will fall to the shoulders of a traveling shepherd boy-charged with delivering wool to his king-with no knowledge that his treacherous journey will decide the pending fate of the world.