Mr. Burns is caught dumping highly toxic waste from the nuclear power plant in the park and is fined $3 million. He pays his debt to society in cash. The townspeople of Springfield hold a meeting to discuss how to spend the money. Lyle Lanley, a fast-talking stranger, convinces them that they need a monorail to put Springfield on the map. Caught up in his sales pitch, everyone votes for the monorail except Marge.

While Homer attends conductor school, Marge stops by Lanley's office to apologize for opposing the project. In his office, she discovers a notebook with pictures depicting Lanley making off with the money meant for the monorail. She drives to one of Lanley's past clients, nearby North Haverbrook, now a ghost town and a victim of Lanley's defective and ultimately worthless monorail. She heads back toSpringfield to warn the others.

Marge is too late. Homer has already taken the monorail on its maiden voyage with Leonard Nimoy and a group of passengers. Lanley has left for the airport with the town's money. Running at full speed, the monorail zooms out of control. Homer fastens a crude anchor and throws it out the window. The monorail comes to a stop--but not before destroying a large portion of the city.