Midnight Magic (Midnight Magic #1)

In this enchanting medieval mystery from Newbery-winning author Avi, the royal castle of Pergamontio is haunted by a ghost that frightens the princess. Charged with uncovering the truth, Mangus the Magician, who remains skeptical about the supernatural, must rely on his clever servant boy, Fabrizio, to solve the mystery using logic and a touch of magic. As the King demands results to save his daughter, the stakes rise, and Mangus finds his life hanging in the balance.