In a war-torn world of elemental magic, a young boy reawakens to undertake a dangerous mystic quest to fulfill his destiny as the Avatar, and bring peace to the world.
Aang awakens to find himself aboard a captured Fire Nation ship with a full head of hair and sustaining serious injuries from the previous battle for Ba Sing Se. At his side are Katara, Sokka, and their father Hakoda who recount the events that led the four to the ship and contemplate their next move. Aang struggles to fight his own desire to face the Fire Lord before he is ready. Meanwhile, the once exiled Prince Zuko deals with his own issues as he makes his long-awaited journey home, with the fear of his father's rejection hanging over his head.
To better blend in as Fire Nation citizens, Aang enrolls in a Fire Nation school, giving himself an opportunity to learn more about the Nation while at the same enjoy life as a normal kid for the first time since he discovered he was the Avatar. Meanwhile Zuko, growing more and more paranoid about the Avatar's false demise, brings himself to confronts his imprisoned uncle.
When Katara expresses her disapproval to Toph's new way to make quick cash, the group finds her too motherly and tension grows between Katara and Toph. When Katara finally decides to participate in this scam to disprove Toph's accusations, they are left vulnerable and are forced to face the dire consequences.
Four days prior the invasion, Aang becomes nervous over his soon-to-come confrontation with the Fire Lord. His anxiety gets the better of him as he begins to suffer from outrageous nightmares and hallucinations. Meanwhile, Zuko becomes upset to learn that he was not informed about a war meeting.
Sokka wants to break his father out of jail and askes Zuko for information on Fire nation prisons. Sokka and Zuko go to the "Boiling Rock" Prison which is in the middle of a volcano to rescue Sokka's father. When Sokka doesn't find him, he feels like he has failed... again... then his hopes are raised when he finds Suki. Sokka, Zuko, Suki and some unexpected allies attempt to escape the prison, but some unexpected surprises come along the way.
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.
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. After the tracker is unable to track Aang, the rest of the group decide they must find Iroh. Meanwhile, while tracking down Iroh, the group meets up with The Order of the White Lotus, a group that transcends the division of the four nations. After a discussion with Iroh the team decides to split up: Sokka, Suki, and Toph head to stop the Fire Nation's air fleet, the masters head to reclaim Ba Sing Se, and Katara, Zuko, and Appa head to defeat Azula.
Aang defeats the Fire Lord by bending the elements within the Fire Lord and removing his fire bending abilities. After Zuko is taken down protecting Katara from Azula, Katara fights and manages to restrain Azula. Afterwards, Zuko is crowned Fire Lord and promises a better future for the world. Aang takes his place as the next Avatar, changing his attire in the process. Katara finally shows her love for Aang as they kiss in the last scene.
Plagued with nightmares featuring the devastating power of his Avatar State, Aang and the gang meet an Earth Kingdom general who has big plans for defeating the Fire Nation. Meanwhile, Prince Zuko and Uncle Iroh, having survived the failed attack on the North Water Tribe, have a surprise visit from the Prince's sister with seemingly good news.
On their way to Omashu, Aang, Katara, and Sokka meet a group of nomads who show them a shortcut through the "Cave of Two Lovers." But when the group becomes trapped in the cave, it's up to Aang and Katara to save the group by trusting in love ... and possibly questioning their relationship. Meanwhile, Iroh gets a lethal rash so Zuko and Iroh head to a small Earth Kingdom town for help, hoping their real identities will not be discovered.
Despite the shocking news the gang have just discovered, Aang insists on trying to find King Bumi within Omashu's borders, even with the dangers that will await him and his friends if his real identity is discovered. Meanwhile Azula goes in search of old friends to help her with her mission.
Aang and the gang discover an Earth town that celebrates something called "Avatar Day." But when they get there and learn the festival is of "anti-Avatar" sentiment and Aang is put on trial for a crime a past incarnation allegedly committed. Looking to clear the Avatar's good name, Katara and Sokka venture back to a familiar place to gather evidence and discover the truth.
In search for an Earthbending teacher for Aang, the kids go to an underground Earthbending tournament called Earth Rumble 6, where they encounter Toph (aka the Blind Bandit), 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.
Toph's instructing abilities come into question when Aang cannot seem to overcome a block that keeps him from earthbending. Sokka gets himself in a jam, while befriending what was, moments before, his next meal, and Iroh and Zuko begin training utilizing new philosophies and methods that originate from the other elements.
When Aang and his friends find a professor who knows of a library that contains information about the world, Sokka decides to go there to hopefully find some information to use against the Fire Nation. The library is guarded by the knowledge spirit, Wan Shi Tong, who doesn't welcome humans into his library, because he believes they only seek information for evil purposes. When Wan Shi Tong discovers Sokka wasn't being truthful with him, he begins to sink the library, bringing the kids down with it. Will everyone be able to escape the library in time? And who are the strange benders who have kidnapped Appa?
When Aang and the gang meet up with a group of refugees, they tell the gang where they can get on a ferry to Ba Sing Se. But after a series of events they have to take a deadly route called the serpent's pass with the help of an old friend, Suki. Meanwhile Zuko and Iroh meet up with a boy named Jet and his freedom fighters.
Having finally made it into Ba Sing Se, the kids are given a house in the upper ring. The kids are anxious to tell the Earth King their plan but there are complications. Meanwhile, still convinced that Iroh and Zuko may be Fire Nation, Jet decides to take matters into his own hands and do whatever it takes to get the refugees to reveal their true nature.
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, Uncle Iroh is offered his own tea shop in the upper ring, and Zuko discovers the avatar is in the city.
Aang is excited about going home (the Southern Airtemple) for the first time in one hundred years, but he is shocked to find out that the temple is deserted. Aang tells Sokka and Katara about his childhood as they explore the temple, but they soon discover something that Aang never expected. Meanwhile, Prince Zuko must make repairs to his ship and the only way he can do it is to dock his ship at his rival's naval base.
After Katara attempts to teach Aang waterbending, but realizes that he is learning it much faster than she is, she is desperate to improve her abilities. When Katara inadvertently stumbles across a waterbending scroll that can help improve her ability while Aang is looking at a pirate’s store, she decides to steal it after she realizes that she couldn’t hope to afford it; but will she be capable of stealing from the pirates without causing herself and her friends trouble?
It's all about instincts...While traveling towards the North Pole, the group almost gets captured by the Fire Nation. However, when a charismatic young man and his band of rebels attack the Fire Nation camp and rescue them, they learn that they are trying to resist the Fire Nation’s motives to expand their territory. Katara and Aang really enjoy their time with the band of rebels, but Sokka soon discovers that they aren’t as noble as meets the eye.
While on their way to the North Pole, Aang and his friends arrive at a giant canyon where two groups of refugees are bickering over who should get to go across. Aang decides to walk across with the two groups to ensure they don’t fight one another. However, he soon learns that the two tribes have been feuding for one hundred years and they both believe their actions are justified. But when the predators inside the canyon start to come out, Aang is stuck trying to defend both tribes from each other and the vicious wildlife.
Aang, Katara and Sokka have run out of money. Katara suggests Sokka get a job, and coincidentally, they meet a fisherman who is looking for someone to help him out with his fishing. But when the fisherman recognizes Aang as the Avatar, he blames Aang's absence for all of the troubles of the last 100 years, and Aang runs away on his glider. Katara follows on Appa, and when she finds him, Aang begins to reveal life before he was frozen in the iceberg.Meanwhile, Prince Zuko and Lieutenant Jee get into a fight, but Iroh breaks it up. Soon thereafter, the Lieutenant and the rest of the crew gain a newfound respect for their leader after learning of his past.
While Aang, Katara and Sokka are traveling, Sokka gets a fever. Katara and Aang try to help Sokka, when only Katara 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.Will Aang save Sokka and Katara in time?And who is this strange figure wearing a blue demonic looking mask?
When the group tries to help a man who is being attacked by a platypus-bear, they discover that the local town has a fortuneteller named Aunt Wu in it, who has been forecasting the town's fate for years. But when Sokka and Aang discover one of the fortuneteller's most vital predictions is dead wrong, they have to develop a plan to convince the stubborn townspeople that their beloved Aunt Wu was wrong.
Aang feels neglected as Katara and Sokka reunite with Bato, an old friend of their father’s from the South Pole. They begin to reminisce on their times in the past while they wait for a message to arrive from their father; in which Aang believes Katara and Sokka will abandon him and go out to find their father should the message arrive. However, when the messenger gives Aang the message to give to Bato, Aang betrays his friends in a way Katara or Sokka could never imagine. However, when Zuko recruits a bounty hunter named Jun to track Aang down, his friendship is put to the test as he must deal with the fact that he betrayed his friends while defending himself from yet another fight.
When Aang and his friends go to a Fire Nation town so that Aang can witness some firebending, their plan soon goes awry when it’s discovered that he is the Avatar. Fortunately, he’s rescued by an individual who serves a firebending master named Jeong Jeong who has abandoned the Fire Nation, so Aang attempts to use this time to attempt to learn how to firebend. However, when the firebending master refuses to even see Aang, will Aang be able to prove he’s ready to learn how to firebend despite the fact that he lacks discipline?
When Aang and his friends hear rumors about surviving airbenders, they decide to stop by the Northern Air Temple on their way to the North Pole to see for themselves. What they find is a bunch of people who are not airbenders, but have mastered the art of gliding; though this upsets Aang because they have been defacing the temple. However, there was one part of the temple where nobody has been able to enter, and what Aang and his friends discover inside spells oncoming conflict.
In the first half of the two-part season finale, 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.
Aang returns from the spirit world to a big surprise. Meanwhile, Zhao and his forces continue to press deeper into the Northern Water Tribe. What could possibly stop the fire nation from destroying this tranquil region? If Zhao has his way, nothing. Also, Iroh makes a powerful stand and Zuko struggles to keep his plan intact.
Narrator James Garrett, the voice of Avatar Roku, explains some of the events that have taken place over the course of Aang’s journey and provides some additional insight into some of the characters. This clip-filled special recaps the adventures of our travelers on their journey throughout the Avatar world, all en route to their ultimate destination, the Northern Water Tribe. It was then followed by a brand new episode, Chapter Eighteen: The Waterbending Master.
After being shot by Azula's lethal lightning attack, Aang falls into a deep slumber. Escape from the Spirit World explains that while Aang's mind and body were immobile, his soul was trapped in the Spirit World. He encounters Princess Yue, the Moon Spirit, who informs him that if he does not reconnect with his past four lives, the Avatar Cycle will end.