Korra leaves the safety of her home and travels to bustling Republic City to begin her airbending training. Once there, she is shocked to find a big city full of dangers, including criminal bending gangs and a vocal anti-bending revolution.

Korra is living with her airbending teacher Tenzin on Air Temple Island. Frustrated with her inability to master airbending, she turns her attentions to Republic City's famous Pro-bending Arena. There she befriends two brothers, Mako and Bolin, who compete in professional bending matches. Korra is immediately drawn to Pro-bending's dynamic fighting style.

When Bolin is captured, Korra and Mako find themselves on the trail of Amon, the masked leader of the Equalists. They gain entry to "The Revelation," a rally of anti-bending supporters, where they discover that Amon has an ability that should be impossible to anyone but the Avatar - the power to take away a person's bending, permanently.

Korra becomes part of Councilman Tarrlok's task force which aims to rid Republic City of the Equalists.

As Asami steals Mako's heart, Korra struggles to express her feelings for Mako and also at the same time Bolin tries to win Korra's heart by being brave enough to ask Korra to go out with him. The tension gets higher as the Pro bending tournament starts.

Korra and the Fire Ferrets are in the pro-bending championship, but will the Equalists allow the game to go on?

Korra suspects that an ally is working with the Equalists.

Korra faces off with Councilman Tarrlok as Equalist activity continues to rise in Republic City.

After being imprisoned by Tarrlok, Korra attempts to analyze the mysterious visions she has been having. Meanwhile, Tenzin, Lin, Mako, Bolin and Asami search for Korra, having been given false information by Tarrlok.

The Equalists begin their attack on Republic City.

Korra goes undercover as the war between benders and non-benders intensifies.

Korra faces the Equalists' mysterious leader, Amon, as the war in Republic City comes to a head.

Korra struggles to find a deeper connection with the Spirit World as she and the gang attend a Southern Water Tribe festival.

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

Korra struggles to maintain peace in the Southern and Northern water tribes when their ongoing feud continues to escalate. Korra begins to doubt on making the right choice on helping Unalaq but her relationship with her parents and Mako become strained. Matters soon become worse for Korra, when Tonraq and Senna get arrested after they are accused of treason.

When Korra's parents are wrongfully arrested, Korra fights for their freedom.

When the President of the United Republic refuses to help Korra, she decides to take matters into her own hands.

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

At the Bhanti Village Temple, Korra is being healed by Fire Sages after being ambushed by a dark spirit. Korra doesn't remember who she is, her past lives inform her that she is the Avatar and in order to regain her memories, Korra must find Raava and if she doesn't find Raava she will die and the Avatar cycle will be over. Along the way, Korra meets Wan, the first Avatar from ten thousand years.

Korra delves deeper into the Avatar's past and realizes what she must do in order to restore balance between the physical and spirit worlds.

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

Korra enters the Spirit World and struggles with the Avatar's relationship with the spirits.

When President Raiko is attacked, Bolin saves the day.

Korra and company attempt to close the spirit portals before Harmonic Convergence.

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.

Korra discovers a way she may be able to defeat the ultimate dark spirit and save the world.

As Korra tries to restore the streets of Republic city, she learns that her decision to keep the spirit portals open has created a new conflict between humans and spirits, and triggered the emerging of new Airbenders.

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.

Team Avatar arrives in Ba Sing Se. While Korra has an audience with the Earth Queen, the others notice that Kai has gone missing, prompting Mako and Bolin to go look for him. They track him down, but he manages to shake them in the monorail, which takes the brothers to the Lower Ring, where they eventually run into their family from their father's side. Meanwhile, Korra and Asami set course for a small village to collect taxes as a favor to the Queen. After getting her money, the Queen brushes off Korra's request for help in tracking down the airbenders, leaving the Avatar to storm out of the palace. In the city, Kai found himself arrested by the Dai Li and subsequently conscripted in the Earth Queen's first airbending regiment.

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.

Korra's search for air benders continues in Zaofu where she meets Opal who has acquired air bending. Korra realizes that Lin has a half-sister named Suyin and their relationship has been strained for thirty years. Meanwhile, Zaheer infiltrates Air Temple Island in a attempt to find Korra. However, Kya recognizes Zaheer and he escapes.

Korra learns how to metal bend from Suyin. Lin takes an acupuncture session, more of her past comes into light such as her job on the police force and her relationship with her family. Meanwhile, Zaheer and his friends plan their escape from Republic City. After Zaheer was caught infiltrating Air Temple Island trying to find Korra, the police force begins to increase their patrols to apprehend the criminals.

Despite Bumi's bad attitude, Tenzin attempts to train the new members of the Air Nation with little success. Things become more complicated for the airbending master as Jinora, with Kai's influence, begins to exert her independence and demand her airbending tattoos. The new airbenders are tested when they are forced to face a group of bison rustlers who have taken Jinora and Kai along with several bison calves.

As Opal leaves for the Northern Air Temple to start her airbending training, Zaheer and his gang try to kidnap Korra. Although Korra's friends are able to prevent this, they suspect that someone inside Zaofu has been aiding the enemy.

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

While en route to Ba Sing Se, Korra and Asami manage to escape from their cell, but their attempt to take control of the vessel results in the vessel losing altitude and hitting the sand. In Ba Sing Se, the Red Lotus hands over Mako and Bolin on condition that they get Korra, and the Earth Queen agrees. Meanwhile, Lin discovers the abandoned Jeep and radios Tonraq to rendezvous at the Misty Palms Oasis.

Mako and Bolin escape Ba Sing Se in an airship as the city descends into chaos. Meeting up with Korra, they deliver Zaheer's message: the Red Lotus will attack the Northern Air Temple unless Korra hands herself over. They manage to contact Tenzin just as the Red Lotus arrives.

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.

The season premiere starts out 3 years after Season 3's end. The Earth kingdom has fallen into anarchy due to the fall out of Season 3's finale. This episode sets up Earth General Kuvira's (aka Great Uniter) mission to reunite the Earth Kingdom.

While Korra is struggling with PTSD by the metal poison Zaheer injected in her, she sets off on a journey to try to connect with Raava. Amidst all of this, Tenzin and the others realize that Korra has gone missing after 6 months.

Prince Wu's coronation doesn't go as planned when Kuvira deems Wu to be unfit as king, due to his great aunt's tyranny three years ago. At the swamp, Toph helps Korra get her back into fighting shape. Meanwhile on Air Temple Island, Tenzin assigns Jinora, Ikki, and Meelo to find Korra.

While the young airbenders look far and wide for Korra, Ikki is briefly captured by two Earth Empire soldiers. Based on what they say, Ikki leads the trio to the swamp. There, Korra is still haunted by visions of being hurt by her past enemies, but manages to connect to the siblings through the great banyan-grove tree's roots. After they beg her to resume her Avatar duties to face Kuvira, Toph's advice helps Korra to let go of her fears, bend the rest of the poison out of herself and re-enter the Avatar State.

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

Korra returns to her role as the Avatar, but is she really ready for action? Bolin and Varrick break from Kuvira's army.

Korra finally returns to Republic City, she reunites with Mako and Asami. However, Korra, Asami, and Mako must work together to rescue Prince Wu from Kuvira's agents. Meanwhile, Bolin and Varrick are on the run after deserting Kuvira's army. Along the way, Bolin and Varrick must help refugees who have escaped Kuvira's re-education camp.

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.

Bolin helps Opal and Lin save the Beifongs from Kuvira. Korra visits the Spirit World looking for help.

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

Team Avatar clashes with Kuvira on the streets of Republic City; Pema and Prince Wu help evacuate innocent citizens.

The fate of the Earth Kingdom and the Avatar's life is at stake, when Korra comes face to face with Kuvira.