While the family visits Shelbyville, the citizens of Shelbyville call Springfield's residents "hicks." This angers Marge, who suggests to the Springfield Cultural Advisory Board that architect Frank Gehry design and build a new cultural center for Springfield. Impressed with Marge's suggestion (which she printed on stationery with Snoopy), he submits his own design which the town approves. The $30 million project is eventually finished and it opens and closes swiftly because no one in Springfield likes classical music (past the first few bars of Beethoven's 5th).
This allows Mr. Burns to swoop in with an idea of his own: take over the space and turn it into a state prison. Although Homer applies for a guard job, he fails the guard test because Otto switches his urine sample (loaded with so many drugs there are only trace amounts of human urine) and Homer's sample. Burns wants Chief Wiggum to bring back some old and forgotten laws in order to fill his prison with convicts. After Homer kicks a can 5 times in a row, he is thrown into jail for illegal transport of litter.
Homer goes to jail, and when he is there, he (unknowingly) snitches on Snake's escape attempt. Burns makes Homer a prison snitch. Without a doubt, Homer snitches up and gets rewarded by the guards, even getting a new plasma TV. During a visit from Marge she loudly exclaims that he was the snitch while other prisoners are getting visits as well. Fat Tony and his goons want to learn about the snitch and tell Homer about a breakout. The guards are waiting outside for the breakout, but a riot from the prisoners who want to get Homer breaks out. It is stopped, with Homer snitching about the prison's conditions. Eventually, he gets released and the governor releases all of the prisoners onto a barge ("where you will all bare-knuckle box until one of you emerges as king of your floating hell").
Meanwhile, Bart and Lisa find out that Snowball II has been gaining weight due largely in part to eating food from another family's house. They also reveal that she has another family. The new family adopts her and names her "Smokey". Smokey likes her new family, and Bart attempts to get her out, but the family fills up Bart with good food. At the end when Homer sneaks out to Moe's he sees Snowball II headed to the bar as well. And all he said was "I won't tell if you don't tell."
During the credits, we see Homer running into the concert, claiming the building is a death trap. But Bart says that Homer had fallen asleep in front of the TV watching The Towering Inferno and that his claim is only a dream. At that rate, Homer gets angry at Bart for knowing the name of his "prophetic vision".