The Missing Heir (Sherlock Files, 4)

Xena and Xander have just learned that their shy classmate, Alice, is the heir to a royal throne! Then they discover that their ancestor, Sherlock Holmes, had his suspicions about the kidnapping and return of Alice's grandmother, the princess of Borogovia.

Alice is to be crowned on her thirteenth birthday . . . but she goes missing days before the ceremony. Who would kidnap a princess? Where would they hide her in a city where Xena and Xander Holmes―and the police!―are looking for her? And then there's the biggest mystery of all: is Alice really the princess?