Ghost Knight

From international phenomenon Cornelia Funke, the bestselling author of Reckless and Inkheart.
Eleven-year-old Jon Whitcroft never expected to enjoy boarding school. Then again, he never expected to be confronted by a pack of vengeful ghosts, either. And then he meets Ella, a quirky new friend with a taste for adventure...
Together, Jon and Ella must work to uncover the secrets of a centuries-old murder while being haunted by terrifying spirits, their bloodless faces set on revenge. So when Jon summons the ghost of the late knight Longspee for his protection, there's just one question: Can Longspee truly be trusted?