One year after the Hundred Year War, Avatar Aang and Fire Lord Zuko are working together with the reinstated Earth King Kuei to remove the Fire Nation colonies from Earth Kingdom territory, but one of the colonies, Yu Dao, complicates matters by taking a stance against the Harmony Restoration Movement and declaring that it will stay no matter what. Aang must take into consideration a promise he made to Zuko just after the end of the War: do whatever it takes to keep the new Fire Lord from becoming like his father, whether that means locking Zuko up or killing him.