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.

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?

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?

This book is written in British English. The story is also available in the Detective Mya Dove 3 Book Collection.