Under Locker and Key
Jeremy is a retrieval specialist. He gets things back that have been taken and has a booming business at his school. He has to be careful though because his arch-rival Becca is always looking for an opportunity to catch him. When Jeremy retrieves something that isn't actually stolen he causes huge issues for the school. He has to work with Becca to get it back before things go horribly wrong.
This was a fun caper story. I liked that it was set in school and Jeremy retrieved things not only taken by other students but also by teachers. What I didn't get was the animosity Becca had for Jeremy and why she was so set in her belief that he was a thief. It didn't seem like the evidence supported that belief. I did like that they worked together in the end.