Zuko follows Aang and his friends to the Western Air Temple, seeking to join their group. There, he desperately tries to prove to them that he has changed for the better. It is only after Zuko helps save them from Combustion Man that he receives their acceptance as Aang's firebending teacher. However, Katara remains doubtful of Zuko's transformation to good and warns him of the consequences of any treachery that he might execute.
After a sore defeat in the Fire Nation on the Day of Black Sun, the elders of the invasion force are now prisoners and the gang travels to the Western Air Temple for refuge. Appa becomes tired from carrying so many people, so they have to walk on foot. When they reach a cliff that descends into a misty canyon below, Toph exclaims that they have arrived at the temple, though no one else sees it. Aang realizes they have indeed arrived, as the temple is built on the underside of the cliff.
Meanwhile, Zuko, who had followed the group from the invasion in his war balloon, arrives first and descends into the temple. He remembers the last time he had been to the Western Air Temple, a week after his banishment; in a flashback, the banished Prince, freshly burned and bandaged, proclaimed that he would scour the world for the Avatar for the rest of his life. He called his uncle Iroh lazy when he suggested that he rest. Ashamed of the memory, his lament is cut short as he sees Appa fly overhead. Zuko runs off to hide, making camp near the temple in a wooded area, and later practices to a badgerfrog his speech to convince Team Avatar to accept him as Aang's firebending teacher.
While Teo, Haru, and The Duke explore the temple, the gang discusses the next course of action now that the invasion failed. Sokka suggests they revert to their old plan of Aang mastering all four elements and facing Fire LordOzai before Sozin's Comet arrives. Aang is less than thrilled at the idea, remarking that they do not even know where to find a firebending teacher. Katara suggests looking for Jeong Jeong, however Aang doubts they will ever see him again. Thinking it is hopeless for the moment, he uses this as an excuse to run off and fly around the temple. The rest of the group follows him on Appa, trying to convince him to stop and continue the discussion. They land and find that Zuko has appeared before them.
Zuko tries to introduce himself politely while Appa licks him in a friendly manner. The group, however, prepares to attack him and refuses to put trust in anything he says. He tries to explain that he has changed for the better and wants to teach Aang firebending. Sokka and Katara continue to point out his wrongdoings and Zuko apologizes anxiously. To try and get on their good side, Zuko reveals that it was he who freed Appa from his imprisonment in Ba Sing Se, but the gang does not believe him. As Zuko continues to apologize, he accidentally reveals he was the one who hired Combustion Man to kill them. Hearing this, the gang resolutely refuses to allow Zuko into their group, threatening to attack if he does not leave immediately. Zuko tries to offer himself as a prisoner, however Katara attacks him with waterbending and tells him never to come back.
Back at his camp, Zuko laments over how terribly things went over. At the temple, the gang ponders Zuko's motives, ultimately deciding that he cannot be trusted. Toph tells them she sensed Zuko was being sincere the whole time and believes the others are letting their hurt feelings affect their judgment. Remembering Toph was not around when Zuko chased and attacked them, the others quickly write off her efforts to defend him. Toph sternly points out how Aang desperately needs a firebending teacher, but Aang adamantly refuses to accept Zuko. Frustrated at the group's continued prejudice, Toph leaves the temple, but not before saying that she wonders who is really the blind one in the team.
While sleeping in his tent, Zuko hears someone coming through the bushes. It turns out to be Toph, but unable to see in the darkness, Zuko immediately firebends at the intruder. Toph tries to defend herself, but the soles of her feet are burned as she steps back. Zuko realizes who she is and apologizes, pleading with her to come back. Toph scurries away on her hands and knees in fear; Zuko tries to help her, but she pushes him away with earthbending. As soon as she departs, Zuko shouts in frustration, "Why am I so bad at being good?!"
The next morning the group wonders about Toph's whereabouts. She earthbends through the wall of the cliff, falling to the ground as she attempts to keep her feet in the air. She admits that she went to visit Zuko the previous night, resulting in his burning her. As Katara begins to heal her feet, Toph explains it was sort of an accident. The gang ignores this and calls Zuko a serious threat, planning to capture him.
Unbeknownst to them, Combustion Man appears on a higher ledge of the temple and prepares to attack the group. Zuko arrives and prevents him from getting a clear shot at the gang, redirecting his attack and alarming the others below. They find cover while Zuko tries to prevent the assassin from attacking them further. Combustion Man instead turns on Zuko and blasts him over the edge of the temple, though he manages to grab hold of a vine below just in time. Aang and Katara use their bending to counterattack Combustion Man; however, their lower position leaves them at a severe disadvantage against him and his barrage of explosions.
While under cover from the attacks, Sokka estimates Combustion Man's position based on the angles at which the explosions hit the ground. Sokka throws his boomerang, curving it around a corner, where it hits the Combustion Man square on his forehead tattoo, blocking his chi, and leaving him disoriented. Combustion Man tries another attack, which backfires and causes the temple building he is on to explode violently. His detached metal arm is seen flying away as the debris falls into the misty canyon below.
Aang thanks Zuko for saving them and Zuko tries, more confidently, to reconcile his past meeting with the group. He admits that he was wrong and says he has learned from his banishment that he must earn his honor by doing the right thing. He tells them he wants to play his part in ending the Hundred Year War, and that his destiny is to help Aang restore balance to the world. He apologizes for burning Toph, stating that fire is a dangerous and wild element and that he must control his bending so that he does not hurt others unintentionally again. Reminded of his own firebending experience that burned Katara, Aang decides to accept Zuko into the group as his teacher, but only if the others agree. Toph says playfully that she accepts Zuko so that she can get back at him for burning her feet, while Sokka accepts him only to help their plan of defeating the Fire Lord. Katara reluctantly agrees, only because it is what Aang believes is right. Zuko enthusiastically promises not to let the group down.
Sokka awkwardly leads Zuko into a room for the ex-prince to use, where the latter unpacks his belongings. Sokka comments to Aang how weird it is having Zuko around. Settled down, Zuko takes out a picture of Iroh and fondly remembers his uncle's advice about destiny. Immediately afterward, Katara appears in the doorway and confronts Zuko. She warns him that while he may have the others convinced, they both know this is not the first time he has struggled to do the right thing. She makes a very clear threat: should Zuko show any act of treachery or any reason to make her think he would hurt Aang, she will not hesitate to take his life. She departs, leaving a visibly disturbed Zuko alone to ponder her threatening words.
New episodes of Avatar began airing in sequential order on July 14, starting with "The Western Air Temple" and ending with the four-part series finale. This event was promoted as the "Countdown to the Comet".
This also was the first episode to be aired after the eight month hiatus.
Many past episodes concerning Zuko's antagonistic relationship with Team Avatar are referenced.
Zuko reminds Aang that the Avatar once asked if the two of them could be friends. This is a reference to "The Blue Spirit", when Aang recalls his past friendship with a Fire Nation boy named Kuzon. Aang asked if he and Zuko could have been friends, had circumstances been different. Another reference is made to this episode when Aang reveals to his friends that it was Zuko as the Blue Spirit who saved him when he was captured by Zhao.
Zuko's flashback shows him and Iroh in search of the Avatar in the Western Air Temple, merely a week after Zuko was banished. At this time, Zuko's wound was still healing and he had only begun his search, journeying to the air temples as a starting point.
This is the last time Zuko is seen with his ponytail.
When Katara suggests Jeong Jeong as a potential firebending mentor for Aang, there is a railing behind where Aang is sitting. When he lies down, it disappears, and reappears again in the next shot.
When Zuko is talking to Iroh in a flashback, Iroh says that it was only one week after Zuko's banishment, but he looks remarkably older than he does in the flashback of his Agni Kai with his father.
When Katara is telling the group about being imprisoned with Zuko in Ba Sing Se, Toph is leaning on a pillar in the background, but the shadows on the floor do not line up with the pillar correctly.
While Toph is walking away from the group, the fountain in front of Toph does not have any water, when just a few frames earlier it did.
Zuko's tunic disappears and reappears several times during the scene where he burns Toph's feet.
When Zuko firebends at Toph, she only steps back on her right foot. In the next frame, it shows both her feet burned.
When Teo says he wants to ride down to the hall of statues again, he rolls onto the screen with the handbrake of his wheelchair in the down position. When he says that he fixed his brakes, he moves the handbrake into the up position and rolls off screen with the brake still in the up position.
When Sokka and Aang help lower Toph's feet into the fountain, Aang's hand appears gloved like Sokka's.
When the members of Team Avatar hide from Combustion Man, Sokka throws his boomerang out to hit him. He quickly runs out to catch it, followed by the rest of the gang, including Toph who walks on her own. However. later on in the episode, right after they accepted Zuko into the group, Sokka had to carry her out because her feet are still injured.
Several times throughout the episode, Aang's staff is shown without the two bulges at its ends.