The series is set in a war-torn world where certain people can "bend" one of the four classical elements – water, earth, fire or air. Aang, the "Avatar" and the last living Airbender, is the bridge between the mortal and spirit worlds, and the only one capable of bending all four of the elements instead of just one. The Avatar maintains the balance of the world and nature to bring peace, and Aang is now faced with the responsibility of ending the ambitions of the militaristic Fire Nation to conquer the world. With his new companions Katara and Sokka, Aang sets out to master the four elements while pursued by Zuko, the exiled crown prince of the Fire Nation, who seeks to regain his honor by capturing him.