Homer takes an interest in the Reading Digest magazine after a copy is sent to the Simpson family's residence. In the magazine, he notices an ad for a children's contest in which an essay must be written about what makes America great. Lisa chooses to enter, takes a trip to Springfield Forest, and is inspired to write her essay when she sees the forest's natural beauty and when a bald eagle lands right by the branch she is sitting under. Lisa's article is approved for entry in the national finals in Washington, D.C. after the contest judge observes Homer's poor vocabulary and realizes that he could not have written Lisa's essay for her.
While Bart and Homer abuse the all-expense-paid perks of their trip, Lisa visits famous monuments for inspiration. At one particular monument, she overhears a corrupt congressman, Bob Arnold, taking a bribe from a representative of a logging industry to demolish Springfield Forest. Heartbroken and disillusioned by the dishonesty of government officials, Lisa tears up her essay and writes a more painful yet truthful essay to show the patriotic judges. The new essay, entitled "Cesspool on the Potomac", disdains and condemns the government system of corruption and greed, and mentions the names of those involved in the bribery. Lisa's essay causes a ruckus and elicits a hostile reaction from the judges and audience. Messages are quickly sent around the capital regarding Lisa's speech and Arnold is arrested, expelled from his job, and sent to jail. Lisa's essay does not win because of its content, but with the news of the congressman arrested and having become a born-again Christian while in prison, her faith in government is restored, while the contest winner commends Lisa for her courage and honesty. The episode ends with Bart slingshotting the annoying pianist that performed at the contest and as Lisa berates him, Bart tells her that she was the one who inspired him to stand up for what he believes in.