Lisa questions Largo’s decision to play Stars and Stripes Forever in the upcoming school band competition at the state fair. A few days later, as the state fair gets underway, Homer enjoys the sounds of veteran rock group Bachman Turner Overdrive, who perform live for fairgoers. Later, the Springfield band finishes performing a rousing version of Coming To America. An excited Lisa runs up to her family, confident the band will win the competition.

But shortly thereafter, the Ogdenville band takes the stage and performs Stars and Stripes Forever. At the finale, the children hold red, white and blue glowsticks into the air, winning over the crowd. Lisa vehemently protests, as she believes the band broke the rules via the use of visual aids.

Later, Homer, Bart and Marge happen upon a carnival act in which a barker forces a horse, Duncan, to jump off a diving board and into a swimming pool. Wiggum pronounces the act a clear case of animal cruelty, and as a result, he horse will be given over to a dog food factory.

When Bart protests, Wiggum tells the boy he can take the horse home if he so chooses. Bart looks hopefully at Homer, who, in turn, looks hopefully at Marge. Later, the family drives home with the horse strapped to the roof of their car.

When the Simpsons return home, Marge calculates that it will cost some $500 per week to keep Duncan. Bart and Homer decide the horse can earn its keep if they race him. They bring the horse to Springfield Downs, where it is entered in a race. With Bart acting as jockey, Duncan is placed inside the starting gate along with the other horses.

But when the starting bell rings, a frightened Duncan peers nervously out of the gate. Bart hugs the horse and bolsters his confidence by telling him, "I believe in you." With that, the horse explodes out of the gate. Unfortunately, the race is already over. Afterward, Bart tells Homer that Duncan is extremely fast, but is intimidated by the other horses.

Homer decides that Duncan needs an attitude. Meanwhile, Lisa decides to write a letter to President Clinton, a fellow sax player, voicing her outrage at the injustice she and her fellow classmates suffered at the state fair.

Homer and Bart transform Duncan via a pimp hat, leather jacket, his Mohawk-style mane. Bart proudly announces that Duncan, the words "Furious D" spray--painted on his side, is now the bad boy of racing. When the next race gets underway, Duncan pulls ahead of the pack and crosses the finish line. Afterward, a victorious Homer and Bart are awarded a trophy in the winner’s circle. Homer taunts the other jockeys, and continues to do so as Duncan wins race after race.

The jockeys lure Homer into the jockey room, where he falls down a chute and lands in a chamber resembling something out of The Hobbit. The jockeys, their expressions now gnome-like, huddle around Homer and laugh like Munchkins. Breaking into song, they warn Homer that he will be killed if Duncan wins the next race.

Homer relays the news to his son, but Bart points out that if Duncan wins the Derby, he can spend the rest of his days as a stud. Eventually, Homer sees wisdom in Bart’s words…and decides to deal with the "murderous trolls" on his own. Duncan wins the Springfield Derby, but at the winner’s circle, angry jockeys armed with a cannon open fire.

Homer and Bart ride off on Duncan, with several furious jockeys, waving sabers and speaking in Munchkin-like voices, in hot pursuit. With some help from Marge and Lisa, the jockeys are knocked from their horses and placed in plastic trash bags.

Later, Homer shows Duncan headshots of fillies he can choose to mate with. Suddenly, President Bill Clinton appears and overturns the results of the band contest. Lisa is overjoyed. Clinton exits...taking the photographs of the fillies with him.