The gang arrives at the Great Divide, the world's largest canyon. Two Earth Kingdom tribes bicker with each other about how to cross the canyon, having been enemies for a century. Aang helps them cross the canyon together, and is able to end the feud by fabricating a story about their ancestors.
Katara and Sokka are arguing over how to set up their campsite, with Aang ending the fight and gloating about his ability to solve problems as the Avatar. The next day, they travel to the Great Divide, the largest canyon in the entire world. Aang and his friends plan to cross the canyon by flying across on Appa. Just before they leave, however, a man runs up to them and warns that Aang and his friends better not leave with the guide to cross the canyon, because he was there first. The team discovers that he is holding a spot for the rest of his tribe, the Gan Jin, until they arrive. While waiting, another tribe, the Zhang, arrive, which the man claims has been an enemy of his tribe for a hundred years. The Gan Jin tribe arrive, neat, prim, and proper in manner, while the Zhang tribe is dirty and barbaric. The canyon guide, an earthbender, subsequently comes, and both tribes begin to argue over who should be escorted first: the Zhangs say that they should because they have sick people, while the Gan Jins say that they should because they have old people weary from travel. Aang proposes a compromise, suggesting that Appa carry their sick and elderly across while the two tribes travel together across the canyon, to which both tribes agree.
The canyon guide warns them not to take any food into the canyon, as food attracts dangerous predators in the canyon. The two tribes, the gang, and the guide begin their descent to the canyon floor. After the guide breaks a rock shelf so that potential Fire Nationsoldiers cannot follow them, a canyon crawler attacks. Aang and his friends fend it off, but not before it breaks both of the guide's arms, disabling his earthbending abilities and therefore imprisoning all of them in the canyon. Both tribes begin to argue again and finally decide to split up. It is revealed later that night that both tribes brought food into the canyon because they believed that the other tribe must have brought it in as well, justifying their actions by stating that they should not go hungry while the other tribe eats. Katara and Sokka each learn one side of the story of the feuding tribes. The Gan Jins tell Katara that the forefather of their tribe, Jin Wei, was attacked while transporting a sacred orb during their redemption ritual by a thief, Wei Jin, from the Zhangs. The Zhangs tell Sokka that their ancestor, Wei Jin, saw Jin Wei passed out on the ground and was returning the sacred orb to Jin Wei's tribe when they wrongfully imprisoned him for twenty years.
The next day, they reach the end of the canyon, where they begin arguing again, both tribes preparing to fight in order to end the feud once and for all. Aang becomes angry and uses airbending to stop them from fighting, but in the process reveals the food hidden by both tribes. Aang scolds the tribes for disobeying the canyon guide's warning not to bring food, but is quickly distracted by an egg custard tart since he has not eaten in a day. However, attracted to the abundance of food, many canyon crawlers approach the area. By working together and throwing bags over the crawlers' heads while the crawlers are distracted with food, everyone is able to ride them up the wall and out of the canyon. Aang, upon hearing the names of the two tribes' ancestors, reveals that he knew them. He says that they were twins and when they were eight, they played a game called "Redemption". Jin Wei was running with the ball and fell, so Wei Jin picked it up and started running to the other end of the field. However, he stepped out of bounds and was put in the penalty box for two minutes. Finally, the tribes make up and continue their journey to Ba Sing Se, the Earth Kingdom capital, together, followed by the guide. Aang then reveals to his friends that the story was fictional. As the group rides away on Appa, Aang asks where the egg custard tart is, as he is starving.
In the real world, the "Great Divide" most commonly refers to the Atlantic/Pacific continental divide, a mountainous ridge that separates the watersheds that drain into the Atlantic and Pacific oceans. The "Great Divide" of the World of Avatar is the exact opposite—a canyon analogous to the real-world Grand Canyon.
The canyon guide is meant to mimic Grand Canyon tour guides, as his explanation of how the Great Divide was created as a parody of the explanation such guides give about the Grand Canyon.
The art and direction style of the Zhang's version of the story is similar to that of the animated film Dead Leaves.
When the canyon guide's arms are broken by a canyon crawler, he states that he has no bending. This is significantly different to other earthbending styles seen. Toph Beifong, on many occasions, uses only her legs. In addition, the earthbender in the opening sequence is seen performing the art with only his legs.
The situation between the two tribes provides an example of a Rashomon effect, in which multiple individuals who are witnesses to an event are able to produce substantially different but equally plausible accounts of it, commonly used in episodes of television programs. The concept was popularized by Akira Kurosawa's 1950s film Rashomon, in which a crime witnessed by four individuals is described in four mutually contradictory ways.
Avatar Extras revealed that canyon crawlers are a cross between crocodiles and spiders.
Overall amongst fans, this episode is the least popular episode in the entire series simply because of its relatively insignificant plot. This fact did not go unnoticed by the creators, and in the play in the episode "The Ember Island Players", the characters chose to fly right over the canyon without stopping, highlighting the inconsequential nature of the episode's events. Avatar Extras references it by saying, "This references an episode called The Great Divide", immediately followed by, "...That episode was not a fan favorite."
The episode title is one of several episode titles that have multiple meanings. It refers not only to the geographical feature, but also to the great divide that has grown between the two tribes, as well as the literal meaning of Wei Jin's name.