In the dense and peaceful Barn Owl Forest, the owl Noctus lives with his wife and children on the branches of a towering tree. Her son Soren (voiced by Jim Sturgess) is extremely fascinated by the legend of the "Guardian". It is said that a long time ago, the evil "purebred" (grass owl) king with a steel beak oppressed the owl people. At the critical moment, the guardian stood up and defeated the king and his minions, but the loser never gave up the idea of revenge. Soren, who yearns for the ancient legend, annoyed his brother Kurud (voiced by Ryan Kwanten) so much that he was pushed down from the tree by his brother. The two little guys who have not yet learned to fly freely fell to the dangerous ground. They avoided the attacks of various beasts, but could not avoid becoming the target of the evil hunter. The two brothers, along with other kinds of owls, were captured to the mysterious Holy Owl School, where they received rigorous training and learned different skills. The long-dormant war in the Owl Kingdom is about to be ignited again... This film is adapted from the classic children's literature by Katherine Lasky.