The Simpsons family attends a monster truck rally featuring Truck-o-Saurus, a giant robotic dinosaur which ultimately crushes the Simpson family car. The rally's grand finale features a death-defying stunt by "the world's greatest daredevil", Lance Murdock. Despite the fact that the act leaves Murdock badly hurt and hospital-bound, Bart is enamored by his performance and dreams of becoming a daredevil. Bart quickly injures himself during his first skateboard stunt by trying to jump over the family car. At the hospital, Dr. Hibbert shows Bart a ward full of children who have been hurt from attempting stunts. Nonetheless, Bart is persistent and continues to pursue his daredevil interest by jumping over a swimming pool and Homer on his hammock. On a class trip to Springfield Gorge, Bart announces that on Saturday, he will jump the gorge on his skateboard. Lisa talks Bart into visiting the hospital to see Murdock, hoping that the daredevil will talk him out of the dangerous stunt. Unexpectedly, however, Murdock encourages Bart to continue on his legacy. Bart plans to do it against the wishes of Homer, who insists that it is too dangerous.
Even after a punishment, several orders, and a "heart-to-heart talk" with Homer, Bart still goes to the gorge and tries to jump it. He is stopped at the last second by Homer, who decides to jump the gorge himself to show Bart what it is like to see a family member needlessly risk their life for no good reason. Bart, not wanting to see his father injured on his account, promises to never jump the gorge and never try to be a daredevil again. However, when Homer goes to hug Bart to make up their misunderstanding, the board rolls down a hill and flies over the gorge, with Homer on board. Although it briefly appears as though Homer will make it safely across, he loses momentum near the middle and plummets to the bottom, progressively becoming severely injured with each fall towards the jagged rocks, and receiving multiple fractures and wounds. A helicopter winches Homer out, slamming his head against the side of the gorge several times in the process before he is loaded into a waiting ambulance, which immediately crashes into a tree as it starts to leave for the hospital. The gurney carrying Homer rolls out of the back, and Homer once again falls to the floor of the canyon. Having arrived at the hospital he is put in the same ward next to Lance Murdock, where he tells him, "You think you've got guts? Try raising my kids!"