Lakeville has become the scene of a strange and puzzling mystery. When Bill King, star reporter for the Continental News Service, told Hop, Tank and Gail what seemed to be a fantastic story. At the moment, the trail of the whistling mystery man seems to have led to a travelling carnival, setting up its tents on the Lakeville fair grounds. Searching for Tank, who had strangely disappeared, Hop and Bill drove to the grounds at two in the morning, where they found Tank sitting watching a tent being raised...