Fortress of the Stone Dragon: A Branches Book (Dragon Masters #17)

Drake has to stop an evil wizard in this action-packed, New York Times bestselling series!
An evil wizard named Astrid is plotting to become the most powerful wizard in the world. She is collecting ingredients for a dangerous spell, and it is up to the Dragon Masters to stop her from casting it. Drake and Mina travel to the Fortress of the Stone Dragon to warn the Stone Dragon's Dragon Master, Caspar, that Astrid is on her way there. But will the evil wizard's dark magic overpower the Dragon Masters?