Aang and Katara work tirelessly to prevent a dispute between Fire Lord Zuko and Earth King Kuei that could plunge the world back into war! Meanwhile, Sokka helps Toph prepare her hapless first class of metalbending students to defend their school against a rival class of firebenders!

The Harmony Restoration Movement has failed, and the four nations are plunged back into war! In the midst of the battle, can Aang and Fire Lord Zuko mend the rift between them, or will Aang be forced to take actions that can't be undone?

The Fire Nation is threatened by a prophecy told by the Kemurikage, mysterious figures thought only to exist in legend: remove Zuko from the throne, or the country will perish!

When Katara and Sokka return home to the Southern Water Tribe, they are shocked to find that it has gone from a small village to a bustling city. Malina, a Northerner, is behind the change and plans to unify the Water Tribes, but Gilak, a Southerner, leads a fierce rebellion to stop her. In the face of these two opposing tribes, Katara will have to make peace with her nostalgia and mistrust to save the home she loves from being permanently torn apart....

Hakoda works to tighten the security of the city, while Katara's distrust of the Northern newcomer grows, and Gilak's crew reveals troubling information.

"When Zuko discovers a clue to Ursa's fate, he enlists the aid of Team Avatar--and enters into a tense alliance with his sister, the deadly and insane Azula--to finally uncover the truth!"--