Henry is off to get photos of a Mississippi riverboat but forgets his camera. Glomer offers to take the kids to deliver the camera, but instead he takes them to 1860s Mississippi where they meet two kids having trouble keeping their riverboat afloat. Punky opens a detective service with her locker as headquarters. Her first client is school brain Herbert, whose hamburger-making machine for the "Build A Better World" exhibition is being sabotaged.