Iroh helps Aang and Katara to escape after Zuko betrays him, and is imprisoned by the Dai Li for his actions. Aang is lightning struck by Azula and is severely wounded. In a final confrontation, Zuko sides with his sister, who promises to restore his honor.

After capturing and impersonating the Kyoshi Warriors, friends of Team Avatar, Azula persuades an elite group of Earthbenders called the Dai Li to instigate a coup d’état, allowing the Fire Nation to capture Ba Sing Se. Azula and her two friends Mai and Ty Lee pursue Team Avatar, who struggle to reach Ba Sing Se, the Earth Kingdom capital, and tell the Earth King of the eclipse. Aang and his friends discover that an upcoming solar eclipse will deprive Firebenders of their bending, leaving them open to invasion and giving Aang his chance to defeat the Fire Lord, but in learning this Aang’s Sky Bison is lost to a group of Sandbenders.

Zuko, with the help of his uncle, tries to come to terms with his troubled past and his obsession with capturing the Avatar. Meanwhile, Zuko and Iroh, now fugitives from the Fire Nation, attempt to lead new lives in the Earth Kingdom. Searching for a new Earthbending teacher, the group meets Toph, a blind Earthbending prodigy who teaches Aang how to “see” using Earthbending and vibrations.

After leaving the North Pole, Aang masters Waterbending under Katara’s tutelage.

Watch avatar the last airbender season 2 episode 17