Before leaving to join the battle, Aang lowers the ice so that Zuko can breathe.
Aang tells Katara and Sokka that he only knows airbending and must master the other three elements.
Katara is given a waterbending scroll that she uses to greatly strengthen and hone her waterbending abilities and to help Aang learn as they make their way to the Northern Water Tribe (where Aang will be able to learn from waterbending masters) and liberate more Earth Kingdom villages in the process, weakening the Fire Nation's food and water supplies.
After defeating Katara in a battle, Zuko captures Aang as he enters the Spirit World to find the Dragon Spirit to give him the wisdom to defeat the Fire Nation who tells him to let his emotions "flow like water".
Returning to his body, Aang battles Zuko before Katara freezes him.
Inside of the iceberg is a thirteen-year-old boy named Aang and a giant flying bison named Appa.
Unknown to them, Aang is the long-lost Avatar — the only person capable of "bending" all four elements of Air, Water, Earth, and Fire.
Katara also becomes a much stronger and more powerful waterbender due to her training with Master Pakku.
Soon, the Fire Nation arrives and Zhao begins his attack while Zuko begins his search for the Avatar on his own.
One hundred years have passed since the Fire Nation has declared war on the other three nations of Air, Water, and Earth in their attempt to conquer the world.
Zuko is the scarred seventeen-year-old exiled prince of the Fire Nation on a quest to find the Avatar and bring him to his father, Fire Lord Ozai, so he can regain his honor.
Sixteen-year-old Sokka and his fifteen-year-old sister, Katara, are near a river at the Southern Water Tribe, a small village in the South Pole.