Homer is trying to help Maggie sleep. After a few failed attempts, she hints him that she wants to hear a bedtime story. He starts by telling the story of the Grand Canyon vacation with the Flanders. The story takes place two years earlier, with people from the church volunteering to clean skid row on a Saturday. At the end of the cleanup, Ned wins a family trip to the Grand Canyon for being the most selfless cleaner. After reading the pamphlet, Ned realizes that it is a two family trip. They invite the Lovejoy family, but they convince Ned to take the Simpsons with them.
At the Grand Canyon, everyone is astonished by the view, but the two families are not getting along very well. Marge is angry at Maude because she thinks that Marge is not a good parent because of Bart and Homer's shenanigans, and the Flanders are annoyed for the same reason. During a donkey trail, they are passed by a group of millionaires that use the canyon at their own wish. Later, the tour guide's donkey falls off the cliff with most of the supplies, leaving both families stranded in the canyon.
Homer manages to make Maggie fall asleep with the story, but Lisa wants to know what happened next. Homer continues telling the story, waking up Maggie who wants to hear it. At the Grand Canyon, Ned and Homer decide to look for supplies when they find the millionaires' camping site. Homer convinces Ned to steal their food and supplies and escape down the river using a raft. They manage to reach their campsite and surprise everyone with a breakfast, with caviar and bacon (which Lisa happily eats; Homer and Lisa then explain to Maggie that the story took place before she became a vegetarian). Later, they are rescued and Homer and Ned talk about their friendship.
When Homer finishes the story, it's revealed that Ned is also listening through the window. Homer reminds him that they still owe them a trip.
In the final scene, postcards from lots of touristic places around the world go past the screen. It is revealed that it's actually the Simpsons family and Flanders family's trip to a postcard museum. When Flanders asks Homer if the place sells postcards at the gift shop, a museum worker states that they don't.