Note: this artical is about the book. You might also be looking for the event.
This artical inclueds spoilers!!!
released in Febuary, 2008, #15: The War of the Ember was introduced as the final book. It inclued many old characters (Coryn, the Band), several nearly forgoten characters (Bess of the Chimes and Sveep) as well as several new characters (Dumpy the 15th). The book was suppost to be the last but there was a notice written from Otulissa's point of view, stating that she was "prepairing the manuscripts" for Guardians of Ga'Hool: Lost Tales Of the Great Tree.
The Guardians learned of deadly plot to hatch Hagsfiends into the owl world. They also discovered that Nyra was amassing an army to conquer the Great Tree, there by crushing the owl world's only form of government. King Coryn knows he is outmatched by his mother, and so begins asembeling anarmy of his own. Instead of Hireclaws, he recruted animals and birds of every kind. From Seagulls to Polars, Puffins to wolves, none the less, he was still outnumbered. He sent out a pack of wolves led by Namara McNamara to destroy the Hagsfiend eggs before they could hatch. Mean while, Coryn waged war against Striga and Nyra. The battle resulted in the Striga's beheading, Nyra turning into a hagsfiend before being hit with a volcanic eruption, Coryn's death, the return of The Ember to its home and finally Soren being declaired king.
"This book, the fifteenth is the last. It is the last not because your fervor has waned but becuase this is the logical place for the story of Soren and the Band to conclued."
- Kathryn Lasky