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 the team's detective skills and math smarts be enough to unravel the mystery?

Find out in this funny, heart-warming third adventure in The Math Inspectors series, perfect for math lovers, math haters, and all kids ages 9-12.