When Lisa struggles to find excitement and intrigue in her family heritage for a school presentation, she decides to take creative license. Inspired by Bart's "Indian butter trick" and the well-known kitchen curtains, with their stalks-of-corn pattern, Lisa claims to be Native American, from the "Hitachi" tribe, a name Lisa selects based on the Hitachi brand of the family's microwave oven. The embellishment turns into a web of lies when Lisa is chosen to represent the school and her "people" at City Hall, then as a keynote speaker for the National Native American Tribal Council. She eventually admits she lied about her heritage, but is spared from prosecution when the other speakers admit they are not true Native Americans. Homer compares his daughter to CBS News in a reference to the 2004 Killian documents controversy. As they leave, Homer mentions that his great-great-grandmother actually was a Native American, and Lisa sarcastically agrees with him, although Homer replies that she did not ask him about it.
At his farm, Cletus is milking his cow when he accidentally kicks over a lantern, prompting a series of Rube Goldberg-esque events that leads to a chicken starting a fire. Cletus's cow succeeds in extinguishing the fire, but Cletus drops his smoking pipe, leading to a wildfire around Springfield. The townspeople try to extinguish it, to no avail. At Springfield Elementary, Principal Skinner asks Groundskeeper Willie to get the fire extinguisher, but all of them have been stolen by Bart to propel his wagon. As Bart rockets around town, the foam released from the extinguishers puts out the wildfire. Bart is cheered as a hero by everyone and rewarded with a driver's license by Mayor Quimby.
Bart starts using Homer's car for his own pleasure, but is eventually tabbed for family errands (mostly chauffeuring Homer). Bart flees to North Haverbrook, where he meets a 15-year-old girl named Darcy, who believes Bart is much older. They begin a romantic relationship and Darcy soon proposes marriage. At the court house, Bart reveals his age, whereupon Darcy reveals that she is pregnant, much to Bart's depression. Darcy admits that Bart is not the father - the real father is a Norwegian exchange student, and she wants to get married because her parents would be upset about her extramarital pregnancy. Bart agrees to marry Darcy, and they drive to Utah, where marriage restrictions are looser. Eventually, Homer, Marge and Darcy's parents catch up with them to stop the wedding, where Darcy's father reasons with Bart as he believes that Bart took advantage of a girl much older than him and got her pregnant. Darcy confesses to her parents that Bart is not the father. Darcy's mother is pregnant too, and the family agrees to pass the two babies off as twins. Darcy and Bart end their relationship, while Bart assures her they will meet again, to which she agrees. Later, Bart admits to Homer that he looked forward to being a father.