Bayport Elementary School is holding a science fair, and first prize is a gift certificate to a cool store called The Nature Place. The Hardys have projects only detectives could dream up—a fingerprint collection and a special spy-scope. Chet's working on a hot dog cooker powered by the sun, and Mike Mendez is putting a camera in one of his robots to make it a burglar detector.

But when two of the best projects get smashed, bully Zack Jackson blames Billy McGee, the new kid in the fourth grade. Billy can be clumsy, but is he really a walking natural disaster? The robot?s eye never lies, but will that be enough to save the science fair?