Best-selling author Alexander McCall Smith enthralls children with Akimbo adventures, Harriet Bean mysteries, and Max Maddy detective tales like Max Maddy and the Chocolate Money Mystery. Wealthy adventurer Harry Helium hires Max and Maddy Twist-world Clue champions and children of private detective legends-to stop a saboteur from affecting a New York to Vancouver hot-air balloon race. But as the race begins and dangerous incidents grow worse, the mysterious culprit lurks closer than anyone realizes.