Springfield grapples with an immigration problem when the economy of nearby Ogdenville collapses.

As Krusty plays Tic-Tac-Toe with Mr. Teeny, Krusty’s agent Ron Rabinowitz warns that the hamburgers sold at Krusty’s restaurant chain are the unhealthiest fast-food items in the world. Krusty develops a vegetable burger for the menu, and before long people throughout Springfield line up for a taste of the healthy meal. Unfortunately an outbreak of food poisoning sends customers rushing for bathrooms. The outbreak is traced to some tainted barley in nearby Ogdenville, settled a hundred years earlier by Norwegian immigrants. Brendlf Jensen, a native of Ogdenville, is interviewed by television newsman Kent Brockman. Jensen matter-of-factly mentions that wherever there’s barley, there are rats. Shortly thereafter the barley mills in Ogdenville shut down. The unemployed workers of Ogdenville flock to nearby Springfield, where they find jobs as day laborers. Homer takes advantage of the situation by hiring several Ogdenville men to help install new gutters on the house. Flanders follows suit, hiring day laborers to build a gazebo in his backyard.

Marge hires an Ogdenville woman named Inga as a nanny. Later Homer and Marge meet Selma’s handsome new boyfriend, an Ogdenvillian man named Torbjorn. Marge and Homer conclude that the influx of people from Ogdenville has worked out well for everyone. One day Bart tries to impress some polite Ogdenville teens with some fancy skateboard moves. In the process Bart injures his arm. Homer and Marge take Bart to a hospital, where they’re forced to wait for hours to see a doctor. Lenny blames the wait on the immigrants from Ogdenville. Tensions mount when the emergency room staff runs out of English forms, and hand Marge a form written in Norwegian. Fed up, Marge returns home, and pops Bart’s arm back into its socket. Homer makes his way to Moe’s tavern, where he samples some Aquavit, a Norwegian liqueur. The beverage is so potent, Homer shows up drunk to work the following day. Mr. Burns fires Homer, sending him plummeting through a trap door in his office. Homer blames his fate on the Ogdenville men who bought him a drink. A wave of xenophobia sweeps through Springfield, prompting Mayor Quimby to close the border and preventing Ogdenvillians from entering Springfield. When Wiggum and his men are unable to prevent illegal border crossings, Wiggum turns to private citizens for help.

Homer organizes a group of men from Springfield. They call themselves the “Star-Spangled Goofballs.” Hoping to catch illegal immigrants, the Goofballs follow a set of footprints at the border... but end up travelling in circles when the footprints turn out to be their own. Later Homer seats himself in a lawn chair tied to some weather balloons. His enormous weight prevents takeoff, so Lenny and Carl climb into the chair hoping to spot illegal border crossings. Eventually Homer turns to big business for help. Mr. Burns offers to erect an enormous fence to prevent Ogdenvillians from crossing the border. At first Marge voices opposition to the idea; but when Maggie’s first words are spoken in Norwegian, she has a change of heart.

Ironically, Ogdenvillians are hired to work on construction of the fence. Once the structure is finished, a silence descends on Springfield. The townspeople realize how much they’ll miss the Ogdenvillians. They invite them back to the city, and celebrate their return.