Bonnie Montgomery (as her case-cracking alter ego Montgomery Bonbon) has been tasked with delivering a priceless diamond to Adderstone Manor, the home of retired master thief Fergus Croke. The plot thickens faster than a good roux when Croke is found dead hours later, and every one of his four protégés is suspected of the dirty deed. But when everyone is a crook, how does even the great Bonbon know where to begin?
With the help of Grampa Banks and an undercover best friend, it's not long before Bonbon uncovers hidden identities, motives a-many, and a rather surprising hedge maze full of monkeys. But can they catch the killer before it's too late?