It's 1956 in eastern Pennsylvania and Mauch Chunk and East Mauch Chunk are about to join to become Jim Thorpe, PA. As part of the July 4 celebration, a soapbox derby race is scheduled for the always-dangerous Fisher's Hill. The South Street Gang gets to work on their racer, only to have it destroyed by the competition. They regroup and create a unique entry with which they hope to go up agains the richest kid in town. In typical fashion, nothing goes exactly as the gang hopes.