Lisa frets about the upcoming Multicultural Day at school. She thinks her family’s heritage is incredibly boring. Bart and Milhouse head to the Springfield salt flats, where they work on a go-cart fashioned out of a cello. Bart slaps a crash helmet on Milhouse, ignites some bottle rockets, and watches as the speedster races off. Moments later the go-cart crashes. Undeterred, Bart forces the battered Milhouse to perform several more tests, which end in more crashes. Lisa watches a television program on Native Americans. She realizes that if she had a Native American ancestor, it would make her Multicultural Day presentation much more interesting. She concocts a fictitious great-great, great-great, great grandmother, a member of the “Hitachee” tribe. Her presentation is a big hit with her fellow students… and with Skinner, who selects Lisa to give her presentation at city hall. Lisa is understandably worried. A short time later Cletus’ son returns home, and announces that he received a C-minus on his report. Cletus is elated, and playfully tugs the tail of one of his cows. This sets in motion a series of events that culminates in a fire spreading through Springfield. Back at the salt flats Bart attaches a series of stolen CO2 fire extinguishers to the speedster. He climbs into the cockpit, and sets off the fire extinguishers all at once. The go-cart zooms through Springfield, dousing the fire and saving the town. A grateful Mayor Quimby grants Bart one wish. Bart says he wants a driver’s license.

Homer teaches Bart how to drive. Lisa gives her presentation at city hall. Everything goes well until a Native American reporter begins asking questions. Lisa is forced to make up more lies to cover up her story. Homer gives Bart a cell phone. He tells the boy he wants him to start pulling his own weight: Bart will be at Homer’s beck and call. Before long Bart receives calls from Homer, asking for a lift or to run errands. Tired of Homer’s constant intrusions, Bart drives to nearby North Haverbrook. There Bart strikes up a friendship with a pretty blonde girl named Darcy. They make their way to a drive-in theater, where Bart and Darcy make out. Before long Darcy asks Bart to marry her. Bart chokes at the thought. Darcy and Bart make their way to a courthouse, where Bart finally admits he’s only ten years old. Darcy’s face falls. She then admits that she’s pregnant. Terrified, Bart runs to the car.

Bart thinks he’s the father, but Darcy assures him that’s impossible. The father is a Norwegian exchange student who is no longer around. Darcy says her parents are going to kill her when they find out what happened. Bart still wants to help Darcy. The pair head for Utah when they find out that marriage laws there are much more liberal. Lisa is invited to perform at a national tribal conference. She finally admits that she made up the whole story about her heritage. A flaming arrow flies though the air. A Native American man steps forward, and tells the crowd that although Lisa is not one of their people, she has shown the type of courage that Native Americans cherish. As pandemonium erupts, Homer tells Lisa that she really does have some Native American blood. When Homer and Lisa return home, Marge tells them about a note Bart left behind. The note explains that Bart and his pregnant girlfriend are headed to Utah to get married. By tracking charges that Bart made on Homer’s credit card, Homer and Marge are able to pinpoint the pair at a chapel in Utah. Marge, Homer, and Darcy’s parents burst into the chapel and halt the marriage ceremony. Darcy explains that she wanted to get married so her parents wouldn’t be ashamed of her. Then Darcy’s mother announces that she’s pregnant. Darcy and Bart say their final goodbyes. When the family returns home, Homer asks Bart to drive him around while he sings public domain songs.