Avatar: The Last Airbender - Book 2: Earth

In this season, after leaving the North Pole, Aang and his friends Katara and Sokka are searching for a new Earthbending teacher, and then they meet Toph - a blind Earthbending prodigy teaching Aang how to “see” using Earthbending and vibrations. After finding important information about the war with the Fire Nation, Appa ends up kidnapped. Their journey leads to Ba Sing Se, the capital of the Earth Kingdom, where they uncover great internal government corruption.