Aang is on the offensive after getting hit in the back of his scar and triggering the Avatar State. Meanwhile, after Zuko seems to have the upper hand against Azula, Katara is forced to join the fight when Azula resorts to desperate measures.

Sokka, Suki, and Toph try to stop the Fire Nation's air fleet. Meanwhile, Zuko and Azula duel in an Agni Kai and Aang confronts the Fire Lord.

Aang returns from the spirit world to a big surprise. Meanwhile, Zhao and his forces continue to press deeper into the Northern Water Tribe. Iroh makes a powerful stand and Zuko struggles to keep his plan intact.

Everyone races against time to stop Azula's sinister plan. Zuko finds companionship in an unlikely source. Aang's destiny hangs in the balance—and so does Zuko's, as Iroh tells him it's time to make a choice.

Zuko travels by himself to an Earth Kingdom town where he meets a local boy. The two almost become friends, while Zuko suffers from flashbacks of his past.

The tale of Avatar Roku and Fire Lord Sozin is revealed to Aang and Zuko by different sources. Both learn about themselves and are shown the origins of the war.

While on the island, Aang seeks guidance from his past lives, but is not pleased with what he is told. The island, in fact, turns out to be a lion turtle from which Aang is given the guidance he had been seeking. Meanwhile, after the tracker is unable to track Aang, the rest of the group decide they must find Iroh. While tracking him down, the group meets up with The Order of the White Lotus, a group that transcends the division of the four nations.

As the invasion force fights their way to the Fire Nation capital, the kids help Aang find the Fire Lord in time for the eclipse. Zuko confronts his father with shocking news.

Zhao begins to launch his attack against the Northern Water Tribe. As the walls of the prestiged city begin to fall, the Avatar taps into the spirit world and seeks the help of one of the oldest spirits, in hopes of saving one of the most prominent areas of the world.

A series of short stories, highlighting different characters and their individual adventures in the city. Tales of Katara and Toph, Iroh, Sokka, Aang, Zuko, and Momo.

While teaching Aang firebending, Zuko realizes that he has lost all his firebending skills. To regain his powers, Zuko and Aang must seek the original source of firebending within the ruins of a lost civilization.

Zuko and Sokka make new plans to break out of the prison with Suki, Sokka's father and some others while a shocking twist leaves Azula none too happy with her two closest friends.

While Aang, Katara and Sokka are traveling, Sokka gets a fever. Katara and Aang try to help Sokka, when Katara also catches the fever. It's up to Aang to go up on his own to save his two friends. But before he can get the medicine he is captured by the newly promoted Admiral Zhao and put in Zhao's fortress.

In search for an earthbending teacher for Aang, the kids go to an underground earthbending tournament called Earth Rumble 6, where they encounter Toph, a blind but powerful earthbending girl. After seeing her unique style of earthbending, Aang wants Toph to become his teacher, but there are complications with Toph's family.

Aang and his friends continue to search for Appa and, unbeknownst to them, they aren't the only ones looking for him. During their search, the kids meet up with Jet, whom they are understandably reluctant to trust. The kids soon realize that the Dai Li are doing their best to thwart the kids' efforts to find Appa. Meanwhile, Iroh is offered his own tea shop in the upper ring, and Zuko discovers the avatar is in the city.

The gang investigates the bizarre disappearances taking place within an eerie town.

The day of the eclipse has arrived, and the invasion force gathers together to make last preparations. They infiltrate the island and the battle begins. Meanwhile, Aang searches for the Fire Lord.

Sokka accepts a job for a fisherman who is looking for someone to help him out with his fishing. After the fisherman finds out Aang is the Avatar, Aang runs away in response to the fisherman's hostile reaction. When Katara finds Aang, he begins to reveal his life before he was frozen in the iceberg. Meanwhile, after Zuko gets into a fight with his crew, Iroh tells them about Zuko's complicated past, attempting to make both sides understand each other.

Tired from trying to escape a machine that shows up every time they try to sleep, Aang and the gang have to escape Azula and her team, but their exhaustion leads to a tight situation. Meanwhile, Zuko must deal with something personal, and Iroh bonds with an unlikely individual.

Aang travels to the Eastern Air temple to receive guidance from Guru Pathik while Sokka is reunited with his long-lost father. Meanwhile, Azula has something diabolical in store for her enemies in the Earth Kingdom, including Zuko and Iroh.

Aang struggles to decide whether or not he has to kill the Fire Lord and, during the night, is drawn toward an island which disappears before morning. Zuko leads the rest of the group to the Earth Kingdom to meet a tracker whom they hope can find Aang. The Fire Lord crowns himself Phoenix King and Aang awakens on the island not knowing where he is.

Having made it to the outer wall of Ba Sing Se, the kids confront a Fire Nation army that is driving a massive Fire Nation drill, which poses an imminent threat to the last Earth Kingdom stronghold. Meanwhile, Zuko and Iroh make crucial mistakes which begin to attract Jet's suspicions.

Appa's journey from being abducted in the desert to the present is explored.

Aang and the group arrive at the Western Air Temple, with Zuko in pursuit. Zuko wishes to help the Avatar end the war by teaching him firebending.

Katara decides to confront the Fire Nation soldier responsible for her mother's death. Aang tries to talk her out of it, but she doesn't listen.