Avatar: The Last Airbender (also known as Avatar: The Legend of Aang) is an American animated television series that aired for three seasons on Nickelodeon and the Nicktoons Network. The series was created and produced by Michael Dante DiMartino and Bryan Konietzko, who served as executive producers along with Aaron Ehasz. Avatar is set in an Asian-influenced world of Chinese martial arts and elemental manipulation. The show drew on elements from traditional Asian (mainly Chinese, Indian and Japanese) culture and Indian religions (Hinduism and Buddhism), while blending the styles of anime and US domestic cartoons.
The series follows the adventures of the main protagonist Aang and his friends, who must save the world by defeating the evil Fire Lord and ending the destructive war with the Fire Nation.
Season One (Book One: Water)
One hundred years before the start of the series, a 12-year-old airbender named Aang learns he is the new Avatar, the only person in his generation capable of manipulating all four elements to his will and the one tasked with maintaining peace between the Four Nations of the world. Fearful of the heavy responsibilities of being the Avatar, coupled with the coming separation from his beloved mentor Monk Gyatso (to complete his training), Aang flees from home on his animal guide, a flying bison called Appa. Caught by a fierce storm, they crash into the ocean, and Aang's protective Avatar State freezes them in a state of suspended animation inside an iceberg. Right after his disappearance, Fire Lord Sozin, realizing that according to the Avatar cycle the next Avatar will come from the Air Nomads, launches a genocidal campaign against the Air Nomads. This way he can ensure that the next Avatar will not try to foil his plots for world domination as the last one of his kind.
Aang becomes unfrozen by a young water-bending girl named Katara, and her older warrior brother, Sokka after being in the iceberg for one hundred years. The three travels to the North Pole so Aang and Katara can learn waterbending. While on their journey, Aang and friends visit the Southern Air Temple, where the new Avatar has a tragic encounter, discovering that the Fire Nation has indeed wiped out every last member of the Air Nomads except for himself, and meets up with the only known remaining "winged lemur" while there, that Aang names "Momo", who joins Aang's group. The trio is constantly being pursued by Prince Zuko, the exiled son of the current Fire Lord Ozai, who can only return to the Fire Nation and reclaim his honor and throne if he captures the Avatar. Zuko travels with his uncle Iroh, a legendary Fire Nation general and older brother of Ozai.
Season Two (Book Two: Earth)
After leaving the North Pole, Aang finishes mastering Waterbending under the instruction of Katara, who has mastered the element faster than he has. Aang and friends travel to the Earth Kingdom city of Omashu to master Earthbending. Their initial plan is to learn under Bumi, king of the Earth Kingdom city of Omashu, but they discover that he and Omashu have been captured by the Fire Nation and Bumi is waiting for the right time to strike. Searching for a new Earthbending teacher, the group meets Toph, a blind Earthbending prodigy who becomes Aang's second teacher and teaches him, amongst other things, her unique ability to use earthbending to "see" vibrations with her feet. After discovering a hidden ancient library, the heroes discover information about an upcoming solar eclipse which would deprive the Firebenders of their bending and open to invasion, giving Aang his chance to defeat the Firelord. They struggle to reach the Earth King with this vital information, but are detoured by Appa's kidnapping. Azula, Zuko's sister, and her two friends Mai and Ty Lee chase the group as they struggle to reach Ba Sing Se, the Earth Kingdom capital. By capturing and then impersonating the Kyoshi Warriors, Azula engineers a plan to manipulate a secret group of earthbenders called the Dai Li to instigate a coup d'état that allows the Fire Nation to take complete control over Ba Sing Se and deal a fatal defeat to the Earth Kingdom, and destroys any hope of the Earth Kingdom staging a large-scale invasion of the Fire Nation. In a final confrontation, Azula kills the Avatar using lightning while Aang is in the Avatar state. By a last minute betrayal by Iroh, Katara is able to escape with Aang's body. Thinking the Avatar is killed, the world begins to believe there is no hope left. In reality, the Avatar has been revived by Katara using water she had received from their water bending master which contains special properties that amplify her natural water bending healing powers.
Zuko deals with internal conflict as he and Iroh defect from the Fire Nation after his father orders his capture and imprisonment for his failures, settle in the Earth Kingdom, and disguise themselves as refugees and eventually end up opening a successful tea shop called "The Jasmine Dragon" in Ba Sing Se. After a brief period of reformation, Zuko again rejoins the Fire Nation when he helps Azula defeat Aang. As a reward, his exile is ended and he is allowed to return back to the Fire nation as a re-instated prince.
In the season finale, while captured by bounty hunters sent by the Bei Fong family to return Toph to her home, the "Blind Bandit" uses her earthbending skills to "see" the particles of refined earth that make metal and becomes the world's first "metal bender," a feat previously thought to be impossible.
Season Three (Book Three: Fire)
Ba Sing Se has fallen, and Aang is critically injured. He awakes to find his group on a Fire Nation ship disguised in similar regalia.
Sokka has planned a small-scale invasion of the Fire Nation to simply capture the Fire Lord's palace and defeat Fire Lord Ozai, making use of their previous plan to take advantage of a soon-approaching solar eclipse which will render Firebending impossible for eight minutes. However, instead of the Earth Kingdom army and navy, the invasion will be staged by a ragtag group of benders and warriors who became allies of the Avatar along his journeys in Books 1 and 2. Aang and his group then infiltrate the Fire Nation and travel to the rendezvous point for the invasion force. Also, Aang starts to have nightmares about meeting the firelord.
The invasion proceeds as planned with the group defeating much of the defenses and capturing the area around the palace, but Aang finds that the palace had been evacuated beforehand and the fire nation had foreknowledge of the invasion; the royal family has taken refuge in a nearby bunker under a volcano and prepared an air fleet in a surprise counter-maneuver. Aang never finds Firelord Ozai, but Zuko does, and uses the eclipse as his chance to confront his father and proclaim his decision to join the Avatar. As the group realizes they have failed in their main objective, they abandon the captured Fire Nation capital and make a desperate effort to reach their ships to escape. However, the pursuing air fleet destroys the protagonist party's ships. Now, only Aang's sky bison Appa can provide a means of escape, and Aang retreats with the children and teens aboard Appa while the adults stay behind and are taken captive.
Zuko catches up with Aang at the Western Air Temple and offers to teach Aang firebending, to complete his training as an Avatar and master all four elements. After a brief conflict, he is allowed to join the group. The two travel to unlock the firebending secrets of the original firebenders, the secretive "Sun Warriors". He and Sokka also plan an infiltration of Boiling Rock, a high-security Fire Nation prison surrounded by the boiling water within a volcanic caldera, where high ranking prisoners of war are kept. They find Sokka's father and Suki, the leader of the Kyoshi Warriors and Sokka's former love interest, but Zuko is quickly discovered and Azula comes to question him, accompanied by Mai and Ty Lee. Both girls eventually aid Zuko and Sokka in escaping the prison, betraying Azula in the process. Enraged, Azula demands their imprisonment and begins to slip into paranoia and insanity at the loss of her most trusted confidants and the later misguiding of her own father, the Fire Lord.
After regrouping, Sokka tries to create a new battle plan to defeat the Fire Lord before he can make use of the approaching Sozin's comet to empower himself and his armies (the worst case scenario the avatar had been trying to prevent since Book 1), but peace-loving Aang refuses when they ask him to kill Firelord Ozai. In his confusion, he is drawn to a mysterious island and meditates on other ways to defeat Ozai by calling on the spirits of other past Avatars for advice. Each Avatar advises him to destroy Ozai, and Aang is reluctantly resigned to killing him until he discovers that the island that he and Momo are on is really an ancient, giant, wise "lion-turtle." Aang asks it for advice, and the Lion-Turtle teaches him the ancient art of Spiritbending as a way to avoid killing Ozai.
On the day of Sozin's Comet, Fire Lord Ozai, now the self-proclaimed "Phoenix King" harnesses the comet's power to start a genocidal campaign to finally annihilate the Earth Kingdom. Princess Azula (Ozai's daughter and Zuko's sister) has come up with a plan to use the airship fleet to destroy the hope of the Earth Kingdom, thus ending it. While Aang and Momo are still missing from their own trip to the "mysterious island", Aang's friends set off to face Ozai, Azula (soon to be crowned the new Fire Lord), and the entire Fire Nation army. Zuko and Katara go to face Azula just moments before her coronation, so that he can usurp the throne in her stead; Sokka, Suki and Toph sabotage the air fleet; and the Order of the White Lotus fights to reclaim Ba Sing Se from the Fire Nation. Aang returns just in time to take on Phoenix King Ozai. Finally reclaiming his ability to enter the Avatar State, Aang almost kills Ozai before restraining himself and instead calls upon the lost art of Energybending to remove Ozai's bending abilities altogether. The war is over, Zuko is crowned Fire Lord, and alongside Aang, he ends the war and promises to bring harmony to the entire world. As Fire Lord Zuko visits his father in prison and demands to know the location of his mother right before the whole group is together for tea in Iroh's teashop in Ba Sing Se. While Sokka is painting a picture of everyone, Aang goes out, Katara follows him, and the series ends with them kissing. Aang and Katara are finally together at last.