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.

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.

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

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

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.

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.