Fablehaven: Secrets of the Dragon Sanctuary

I liked this book written by Brandon Mull. The evil Society of the Evening Star is ruthlessly pursuing five ancient artifacts. After the Society pilfers two artifacts, Kendra races to discover the location of the third. However, it lies deep within the dragon sanctuary of Wyrmroost. To save the treasures from falling into the wrong hands, Kenda and the other Knights of the Dawn infiltrate the dragon dungeon.

This is the fourth book in the series.