After finding out that the Fire Nation has taken Omashu. Aang, Katara, and Sokka sneak into the city so they can bust out King Bumi, but things get complicated when Mai's younger brother, Tom-Tom becomes a stow away. Aang tries to bring Tom-Tom back in exchange for King Bumi's release, but Azula decides not to fulfill her end of the deal. Aang tries to get Bumi out, but the king convinces Aang that there is another earth bending master who can teach him. Aang finally returns Tom-Tom to his parents and he goes off to find the earth bending master that Bumi has talked about.
—dawsonpersi