Superintendent Chalmers organizes an exchange of the very worst tenured teachers between the schools in the district, moving the notorious Mr. Jack Lassen to Springfield Elementary School where he will teach Bart's class. He bullies Nelson and gives Bart an embarrassing haircut, so Bart schemes to bring him down, with the help of Milhouse. Using a fake social network profile in the name of Miss Hoover, they discover that Lassen is due to perform an important ritual at a desert festival called "Blazing Guy", where he will light the eponymous effigy.
Meanwhile, Homer has forgotten to book a campsite, which upsets Marge. Bart solves both of their problems by telling Homer to take the family to Blazing Guy. Marge, who is disturbed by the eccentric campers, drinks a cup of tea to relax, although it contains hallucinogens, making her delirious. Bart and Milhouse use fire retardant substance to make sure that the effigy will not light, therefore ruining Mr. Lassen's important moment. He is furious and grabs a burning tuba, from which he blows fire in an attempt to kill Bart and Milhouse on top of the effigy. Homer tries to save the boys by using a catapult to launch himself onto the effigy, but falls short and breaks its leg, destroying it. The other campers form a wall around Lassen and declare him to be shunned from the festival, while Bart and Milhouse escape safely.
Superintendent Chalmers and Principal Skinner fire Lassen from teaching at Springfield Elementary or any other school. Lassen then finds a new job as a prison guard. While ordering lights-out to the inmates, he encounters inmate Sideshow Bob. Discovering that they both murderously detest Bart Simpson, Lassen offers a partnership to kill Bart, which Bob nearly accepts. But when Lassen declares that they share the final kill, Bob rejects the deal.