Korra and Chief Unalaq journey into a dangerous maelstrom and find a source of great spiritual power.

When Triad activity threatens to put Future Industries out of business, Mako performs an investigation and discovers a much bigger conspiracy.

Korra seeks Tenzin's help to enter the Spirit World for the first time.

When President Raiko is attacked, Bolin saves the day.

Korra discovers a new twist in Unalaq's evil plan. Meanwhile, Tenzin realizes he must face his own demons in order to save his daughter.

Tenzin, Jinora, and Team Avatar travel toward Ba Sing Se in order to find the new airbenders. Stopping at various villages along the way, they hope to recruit them in order to rebuild the Air Nation, though with little success as they were only able to convince a young boy named Kai to join them. Meanwhile, Zaheer travels the four nations to free his fellow criminals from their prison. After freeing Ghazan and Ming-Hua, they set course for the Northern Water Tribe to free their last member, P'Li. Upon learning of their escape, Lord Zuko sets course for the Northern Water Tribe himself in an attempt to stop them.

Lord Zuko, Tonraq, Desna, and Eska try to prevent Zaheer from freeing the last prisoner, P'Li, while Korra discovers that the Earth Queen is forcing all the airbenders in Ba Sing Se to join her army. Team Avatar thus devises a plan to free them from the monarch's captivity.

Zaheer and his gang try to kidnap Korra.

Mako and Bolin deliver an ominous message from Zaheer.

Korra battles Zaheer, while Bolin and Mako duel Ghazan and Ming-Hua. The captive members of the Air Nation escape and band together to help Korra.

It's been three years since Zaheer poisoned Korra and the members of Team Avatar have moved on with their lives; Kai and Opal help a struggling Earth Kingdom town.

Kuvira threatens Zaofu; Bolin is caught in the middle of the bad blood between Su Beifong and Kuvira.

In a clip show episode, Mako, Korra, and Bolin recollect their past. Mako tells Wu about his romantic entanglements and eventual breakup with Asami and Korra. Korra talks to Asami about her confrontations with Amon, Unalaq, Vaatu, and Zaheer. Varrick presents Bolin's life to the Earth Empire refugees in the style of an action film in which Bolin defeats all of Korra's previous enemies.

The spirit vines in Republic City start abducting people and it's up to Korra to figure out why.

Korra and Team Avatar try to stop Kuvira from moving against Republic City; Kuvira unveils a deadly new weapon.