Max and his fellow Grey Griffins, Ernie, Harley, and Natalia, set off on another extraordinary adventure — traveling to Scotland to visit Max's dad for the winter holidays. It doesn't take long before strange things start to happen to the four kids while they explore Mr. Sumner's ancient castle. Once again, the Grey Griffins must do battle with the forces of evil — Fireball Pixes, Werewolves, and Morgan the Black Witch. But when Max's dad disappears, it's up to the Grey Griffins to rescue him, with the help of Knights of Templar! This sequel to The Revenge of the Shadow King is a fast-paced page-turner where trouble lurks around every corner, but the most dangerous thing of all is knowing who can truly be trusted.