Exile — Kathryn Lasky

Sometimes the enemy comes from within....
Slowly, inexorably, the Striga, a mysterious blue owl from the Middle Kingdom, gains control over young Coryn's mind. And then the unthinkable happens. The Band is banished from the Great Ga'Hoole Tree. The Striga institutes a harsh new regime that will not stop until learning itself -- the very foundation of the tree -- becomes suspect and books are consigned to flame. Somehow the Band must open Coryn's eyes to the Striga's malign influence. But how? They are in exile!