Would-be detectives Trevor, Nick and Robyn are hot on the trail of a sandwich thief when they learn that more than food has been going missing at school. A valuable hockey book has been stolen from the library, and the kids worry that the librarian might lose her job if it isn't found. Who would steal a hockey book? Could it be Robyn's arch-nemesis and hockey enthusiast Clay? Or could it be Ms. Thorson, the Oiler fan teacher? The kids are determined to solve these mysteries even though their sleuthing efforts land them into trouble at every turn.