<p>Mya is investigating Libby the new girl at school. Libby won't speak smile or play with anyone. The Children's Police Force thinks she is mean but they need proof.</p><p></p><p>Finding proof is Mya's job. It won't be easy. Libby isn't just mean she is sneaky too. When Mya talks to her Libby fake cries in class. Now Libby has a teacher on her side. Who will she trick next?</p><p></p><p>To solve the case Mya must prove that Libby is mean and warn everyone. Can she stop Libby before it's too late? Or will this mean girl take over the school?</p>