With fake drivers ID in hand, have Bart will travel. In this case, Nelson, Martin and Milhouse come along for the ride when Bart hits the wide open road. Meanwhile, Lisa spends some quality time with Homer at the power plant.
It's the last week of school before Spring Break at Springfield Elementary. Principal Skinner is planning on spending the break in Hong Kong, but he discovers that the airline has mistakenly booked him for a flight that leaves on Friday instead of Saturday. Unable to pay the huge fee that the airline would charge to change the flight date, Skinner decides to promote a "Take your kids to work day" on the Friday before Spring Break. Bart very reluctantly goes to the DMV with Patty and Selma (his first choice was staying at home with Marge), Lisa goes to the nuclear power plant with Homer, Milhouse discovers the exciting world of Crackers, and Martin makes a million dollars trading commodity futures (although seconds later, he loses all but $600).
At the DMV Bart makes himself a fake driver's license. He, Nelson, and Milhouse are unsatisfied with its local uses, such as admitting them to see the film version of Naked Lunch, which they assumed to be pornography. They eventually decide to use some money that Martin has to rent a car and go on a road trip. As a cover story, Bart, Martin, and Milhouse tell their parents that they have been selected by their school to attend the National Grammar Rodeo in Canada. Lisa, who has never heard of such an event, can easily see through Bart's lie, but Marge believes that Lisa is trying to get attention. Martin and Milhouse have no problems convincing their parents. Nelson just tells his mother that he is going away for a week.
The boys rent a vehicle and head out, but soon stop when they suddenly realize they have no idea where they are going. Finding an old brochure in the glove box of the car, they decide to go to the World's Fair in Knoxville, Tennessee. But first Nelson makes them stop in Branson, Missouri (Bart: "Dad says it's just like Vegas... if it were run by Ned Flanders"), where he can see his hero, Andy Williams.
Back in Springfield, Homer asks if Lisa would like to come spend her spring break at work with him and she enjoys herself there; meanwhile, Marge becomes bored at home. Finding out that the World's Fair was over 10 years ago (the Knoxville World's Fair was held in 1982, nearly 14 years before the episode originally aired), and the aging Sunsphere has been turned into a wig shop, Bart and company do not find Knoxville that exciting. Nelson throws a rock, toppling the Sunsphere, which then wrecks the car. They are stranded with no money and no car, nobody knows where they are, and they cannot tell their parents.
Bart calls Lisa and tells her the truth, which confirms her earlier suspicions, and she suggests that he become a Courier as a possible way to get home. Bart manages to get a job (even with his un-laminated, unsigned license). His first job takes him to Hong Kong to deliver eyeballs, while his friends stay behind (during the trip, Principal Skinner sees Bart at the airport). After several more deliveries, Bart calls Lisa and mentions that she needs to help him find a way to get a package shipped to Springfield, and big enough to hold Martin, Milhouse and Nelson.
The next time Lisa meets with Homer, she explains just what Bart has been up to. Homer vents his displeasure by yelling into one of the plant's safety helmets. After causing his nuclear console to malfunction (by pouring a can of Buzz Cola on the controls), Homer orders the plant a new nuclear console from the Oak Ridge Nuclear Facility in a crate. Bart forces Nelson, Milhouse, and Martin to get in the crate while flying home, and everyone knows about the trip except Marge, who receives a call from Skinner asking if Bart traveled to Hong Kong, a call asking whether her son's car was abandoned in Tennessee, and a call inquiring about Bart's availability to make another international delivery.