Bart becomes deeply immersed in competitive soapbox racing while Homer begins to realize that he's not as good a father as he thought. After attending a lecture at National Fatherhood Institute, Homer becomes a more attentive father, helping Bart build the ultimate soapbox racer. But Bart decides not to use it in his big race against Nelson Muntz, instead opting to borrow Martin Prince's scientifically engineered aerodynamic racer.