this could be the sypnosis.
aang,katara and sokka have return to the south pole but they notice that is a bigger evil than the fire lord so it depends on aang to save the world again,but they need help so they will go to call toph again,aang and katara get their relationship to another level meanwhile zuko and iroh had to hid of this new evil but first aang and the gang had to warn omashu of this because it will be the first target of the new evil.??will aang and the gang?? save the world?.