When Marge catches Bart vandalizing a town sidewalk, she lectures him on the importance of town pride. Afterwards, Bart realizes how wonderful it is living in Springfield. Consequently, however, Bart also becomes more upset with anti-Springfield sentiments coming from the neighboring town of Shelbyville. Grampa explains that this rivalry can be traced back to the establishment of the two towns. This occurred when the founders Jebediah Springfield and Shelbyville Manhattan discovered they had irreconcilable differences regarding their visions for a perfect town, Springfield favouring promotion of chastity and Shelbyville advocating incestuous marriages between cousins.
The next day, Springfield's lemon tree is stolen by children from Shelbyville. Taking his town pride to heart, Bart leads Milhouse, Nelson, Martin, Todd, and Database into Shelbyville. The group splits up and has a few misadventures. Bart goes undercover and infiltrates the kids of Shelbyville by disguising himself. However, he is unable to obtain any information. Eventually they track down the tree to an impound lot.
Back in Springfield Homer, using Flanders' RV, leads the adults to find the children. When the two groups meet, the children convince the adults to help recover the tree. Homer demands the return of the tree, while the owner of the impound lot refuses. Using a plan similar to the Trojan Horse, Bart steers the RV to the ouside of the hospital. The RV is taken to the impound lot after it is found parked outside the hospital. When night falls, the Springfieldians get out of the RV and tie it to the top. They are caught in the middle of this act but manage to escape. The tree, though slightly damaged during the raid, is returned to Springfield. The children of Springfield celebrate with lemon juice, while those in Shelbyville drink turnip juice.
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