It's Christmas Eve in Ravensburg, and the town is bursting with anticipation for its oldest Christmas tradition. The annual opening of Douglas and Son's Toy Store, home of the greatest toys in the world, is finally here. But this is no ordinary Christmas Eve, and the surprise that awaits them is beyond any of their wildest imaginations: a surprise that threatens to ruin Christmas! Stanley, Charlotte, Gertie and Felix call in a little backup, but will...

"Summer vacation has finally arrived, and the Math Inspectors deserve a break. After all, their sixth-grade year was a busy one. On top of all the normal school stuff, Stanley, Charlotte, Gertie, Felix, and Herman made quite a name for themselves as amateur detectives. But when a relaxing day of roller coasters, riddle booths, and waffle eating contests turns into a desperate scramble to save a beloved landmark, the friends quickly discover that this...