Aang and his friends meet a general from the Earth Kingdom intent on destroying the Fire Nation. Prince Zuko gets a surprise visit from his sister.
Aang, Katara, and Sokka journey into a cursed cave with some nomads in the hopes of getting to Omashu quickly. Prince Zuko and Uncle Iroh seek medical help in the Earth Kingdom.
With Omashu under the Fire Nation's control, Aang and friends must be careful to find King Bumi undetected. Azula continues on her mission.
Mysterious visions plague Aang, Katara, and Sokka while in a strange swamp searching for a lost Momo and Appa.
Aang is captured during an anti-Avatar rally and is put on trial for past life crimes. Katara and Sokka try to find a way to help Aang before it's too late.
While looking for an earthbending teacher, Aang meets a blind girl with amazing skills. To get her as a teacher, Aang and his friends must help her overcome her personal problems.
Zuko is plagued by memories from the past when he breaks away from his Uncle Iroh and journeys to an Earth Kingdom town alone.
Aang comes upon a roadblock in his earthbending instruction with Toph. Zuko tries to train for the future using techniques from the other elements besides fire.
Sokka tries to find information at a massive library that will help he and his friends defeat the Fire Nation, but a spirit won't let the library be used by humans.
Aang searches for Appa, while Katara struggles to keep everyone together so they can survive in the vast desert while Sokka supposedly gets "high" of Cactus juice in the desert. Meanwhile, Iroh and Zuko seek help from an ancient secret society. Will Aang find his furry friend or did the sandbenders cause a catastrophe?
Aang and his friends must take the Serpent's Pass on the way to Ba Sing Se with the help of Suki. Zuko and Uncle Iroh meet Jet and his group on their journey.
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. Can Zuko and Iroh keep their cover? Will Aang manage to save Ba Sing Se from the Fire Nation?
Aang and his friends try to tell the king of Ba Sing Se their plans to stop the Fire Nation, but are unable to. Jet tries to find out Zuko and Uncle Iroh's true identities.
"The Tale of Toph and Katara" Katara tries to convince Toph to join her at a day spa for a ladies' day out."The Tale of Iroh" While on the way to return home from the market, Uncle Iroh educates many of the townsolk he passes.
Since being captured, Appa's adventures back to Aang include being sold to a circus and returning to his home to heal.
Aang and Zuko separately search for Appa, but Zuko finds him first and sets him free. Long Feng tries to take possession of Jet in an effort to destroy the Avatar.
Aang, Katara, Sokka, and Toph try to reach the Earth King, but are forced to battle the Dai Li and Long Feng. Zuko faces a spiritual dilemma when he becomes feverish.
Zuko is pleased to open the tea shop with his father. Azula continues infiltrating the Earth King's inner circle. Aang goes to meet the guru who will teach him to gain control of the Avatar state.
When Azula threatens Zuko and Uncle Iroh, Zuko decides to finally confront her. Uncle Iroh calls on his old friend Toph to enlist the aid of her, Aang, and Sokka in rescuing Zuko. But they are unable to stop Azula when Zuko joins her and the Earth Kingdom falls under the Fire Nation's power.