The Giant Yo-Yo Mystery

The Alden children, the siblings from the Boxcar Children series, help a friend of their grandfather build the world's largest yo-yo in hopes of breaking a record. While constructing the massive toy, they discover they're being followed, the yo-yo's plans go missing, and clear signs of sabotage appear. With several Greenfield residents working against them, the children must piece together clues to find out who is trying to stop the project and why. The mystery unfolds as they race to complete the giant yo-yo before it's too late.