The Disappearance of Emily H.
I did not see the twist in this coming, which is always a welcome surprise. Along with murder mysteries (which, oddly, are not often written for middle grade readers!), my students ask for books where children are kidnapped, things like Duffy's Missing, Kehret's Abduction, and Robert's Hostage. This is a refreshing addition to that type of book, rather like Corrigan's Accomplice. The mean girls are realistically drawn, and Raine's difficulties with her own mother add an interesting perspective to the story. It doesn't hurt that cross country is involved, either!