Uncle Alonzo stretches the truth to his nephew Bobby. Bobby's father's car breaks down taking Alonzo to a train station. They are rescued by a superhero, RD-119, who shrinks Alonzo, Bobby, Bobby's father and dog for a tour of the corroded inside of their car, the Sinclair refinery and the Sinclair Research Laboratories. They learn about the new gasoline additive RD-119 that prevents corrosion.