The Rescue - Guardians of Ga'Hoole Series #3

Now that Soren has been reunited with his sister, Eglantine, he must face his next challenge: making sense of the mysterious disappearance of his mentor, Ezylryb. When Soren discovers that Ezylryb is in danger, he and his friends Gylfie, Twilight, and Digger devise a plan to save the beloved teacher. In this process, Soren must fight a ferocious foe who wears a terrifying metal beak, sharpened for battle. It's not until the confrontation is over that Soren discovers the true identity of his opponent. Paperback