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.

Per Su's suggestion, Korra begins to learn metalbending. Opal admits her reluctance to leave Zaofu due to her obligations to her family while Bolin deals with his fear of learning how to bend metal. Meanwhile, Lin faces her past during an acupuncture sessions, forcing her to relive the circumstances which led to her and Su's strained relationship. After a cathartic release of her repressed emotions, Lin makes amends with her sister as well as Opal, who she convinces to travel to the Northern Air Temple to train with Tenzin. Elsewhere, Zaheer and his group determine Korra's whereabouts shortly after escaping Republic City, deducing that she was under the Metal Clan's protection in Zaofu.

Zaheer and his gang try to kidnap Korra.

Korra learns the truth about the group that is planning to destroy her.

Korra and Asami are stranded in the desert. The members of The Red Lotus negotiate with the Earth Queen.

Mako and Bolin deliver an ominous message from Zaheer.

When other plans fail, Korra suggests a brave idea to take on the Red Lotus and save the Air Nation.

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.