Exile (Guardians of Ga'Hoole, #14)

Slowly, inexorably, the Striga, a mysterious blue owl from the Middle Kingdoms, gains control over young Coryn's mind. An 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!