The shattering

Soren's younger sister, Eglantine, starts having strange dreams that feel like trances. Then she disappears. Soren soon understands that she has been brainwashed and turned into a spy for the enemy, without any idea of what she is doing.

The enemy is Kludd and his Pure Ones, who are fighting the owls of the Great Ga'Hoole Tree in a war that has grown desperate. Soren will not abandon his sister. He leads his fellow Band members, Twilight, Gylfie and Digger, into a dangerous region called the Beaks, hoping to find Eglantine and reverse what has been done to her.

Their search runs straight into Kludd's advancing army. The fight that follows is a large battle, made worse by a forest fire raging around the combatants. Courage and loyalty within the Band are tested as the war for Ga'Hoole reaches another turning point.

This is the fifth book in Kathryn Lasky's Guardians of Ga'Hoole series, a fantasy about owls at war. It moves from a creeping mystery at home to a rescue mission and then open combat, with the stakes rising at each stage.