Guardians of Ga'Hoole Book 4: The Siege

Written by: Kathryn Lasky

First line: Sparks flew off his beak as the owl, mad with rage, careened through the night sky.

Why you should read this book: The stakes have been raised as Metal Beak, revealed as Soren's brother, Kludd, further reveals the depths of his evil and depravity, along with his utter hatred for his brother. Meanwhile, Soren and his chaw of chaws have been entrusted with a terrifying and important mission: to return to St. Aggie's as undercover agents and determine whether the academy has been infiltrated by the Pure Ones. War between the Guardians and the Pure Ones is imminent, and the Pure Ones have on their side greater numbers, superior weaponry, and a fierce rage that drives them onward toward genocide.

Why you shouldn't read this book: You're a double agent.