Kat & Mouse, Volume 4: The Knave of Diamonds Alex de Campi Author

Chloe's diamond necklace has been stolen by the Artful Dodger, and it's up to Kat and Mouse to find it. However, this is no ordinary middle school mystery, and to solve it, Kat must at last determine the Dodger's true identity. By the time this case is solved, Dover Academy will be shaken to its very core!