Homer and Bart learn that Truckasauras--a giant fire-breathing mechanical dinosaur made out of trucks--is coming to the Springfield Speedway. Homer proposes that the whole family attend the event, even though it falls on the same night as Lisa's saxaphone recital. Homer and Bart anxiously sit through the performance and then rush the family to the rally. Entering the speedway arena by mistake, the Simpsons' car is mauled by Truckasauras.

At the show, Bart is entralled with the stunts of fearless daredevil Captain Lance Murdock. When Murdock's stunt goes awry, he is pulled from a shark-and Lion-infested tank to a rousing ovation. Bart knows he has found his calling. Performing his first stunt in front of the local kids, Bart flies off his skateboard and smashes into the pavement. Dr. Hibbert gives him a safety lecture, while Captain Murdock, healing in the hospital, urges Bart to live on the edge.

With Murdock's encouragement, Bart decides on the greatest stunt of his life: jumping the Springfield Gorge. Homer concludes that the only way he can stop Bart is to do the stunt himself and show Bart how dangerous it is. He mounts Bart's skateboard, but Bart, knowing Homer will surely die if he tries the stunt, agrees to give up his daredevil career. Homer accidentally rolls backwards down the ramp. Airborne, he feels the elation of the flight, but runs out of momentum and crashes into the gorge. As his ambulance is taking off, it hits a tree, causing the rear doors to open and Homer rolls out, still on the stretcher, and falls down the gorge again.