|"Now, ten thousand years of darkness begins."|
|— Unalaq to Korra, Mako and Bolin.|
"Darkness Falls" is the thirteenth episode of Book Two: Spirits of The Legend of Korra, and the 25th episode of the overall series. It was released on Nick.com on November 16, 2013, and aired on Nickelodeon on November 22, 2013. On both platforms, it was paired with "Light in the Dark" to form the first part of a two-part season finale.
Despite her best efforts, Korra is unable to prevent Vaatu and Unalaq from merging and forming the Dark Avatar. Battling for the fate of the world, the fight between the two Avatars ends when Vaatu forcibly separates Raava from Korra's body and destroys the Light Spirit's physical form, effectively severing Raava's connection to the past Avatars. His counterpart destroyed, the Dark Avatar grows to a massive size and uses the spirit lights that cover the sky of the entire world during Harmonic Convergence, to transport himself to Republic City. Meanwhile in the Spirit World, Bumi, Kya, and Tenzin manage to track down and save Jinora's spirit from the Fog of Lost Souls. However, before they can return, Jinora senses that Korra is in trouble and leaves her family in order to help.
Free from his prison in the Spirit World, Vaatu taunts Korra by emphasizing that his release was inevitable and that Harmonic Convergence was upon them again. Korra promptly declares to prevent him from fusing with Unalaq to create the Dark Avatar and imprison him again. As Vaatu moves toward a willing Unalaq, Korra enters the Avatar State to blasts the dark spirit away from him with firebending before using airbending to lift Unalaq into the air and hurl him back through the Southern spirit portal. Telling Bolin and Mako to keep Unalaq out of the Spirit World, she enters the Avatar State again, resuming her attack on Vaatu.
Meanwhile, Tenzin, Kya, and Bumi search for Jinora in a spirit forest. Having found nothing, Bumi suggests that he try to track Jinora's spirit, but Kya wonders if spirits even leave footprints to track. As an alternative, she begins to meditate and points to her left after a moment, noting she feels a high concentration of spiritual energy coming from that direction, though Bumi frustratingly shouts that they are in the Spirit World, surrounded by spiritual energy. Deducing that they cannot find Jinora by themselves, Tenzin declares they need to find a spirit guide. To that end, the trio walks toward a hollow tree to request the help of the spirit residing within. His plan backfires when the tree's inhabitant, a dark spider spirit, angry that it has been woken, charges at the siblings and runs them off a cliff. As they recover and take in their new surroundings, they realize that they are completely lost.
By the Tree of Time, Korra continues to barrage Vaatu with every element that she can command, managing to land a few blows. The Spirit of Darkness strikes back, however, and hits her square in the chest with his energy beams, knocking her back against a rock. As the Avatar sags down, Vaatu reaches through the earth with his tentacles, sprouting vines next to Korra that instantly twist around her, locking her in a tight grip.
Meanwhile, Bolin and Mako are on the lookout for Unalaq outside the Southern spirit portal when they are attacked by a barrage of flying ice shards. Bolin erects a wall in their defense, allowing Mako to hurl fire at their unseen opponent before Bolin follows up his attack with the wall. They can only enjoy a short reprise as another ice attack cuts through the air toward them. Defending themselves against several attacks, Bolin muses that they may not be able to win the fight, prompting Mako to note that they do not need to win as much as they need to keep Unalaq from reentering the Spirit World.
Back in the Spirit World, Tenzin grows increasingly frustrated, realizing they have been walking in circles as they keep passing the same mushroom. The mushroom, alive, confirms this. His and Bumi's brewing argument is cut short, however, when Kya hears a noise, which turns out to be made by Iroh and a Knowledge Seeker, who offers to guide them out of the Spirit World. Tenzin expresses his gratitude but informs Iroh that they do not intend to leave the Spirit World without Jinora. Iroh warns them to be cautious when venturing into the Spirit World, as they could find themselves in "a place where only the lost will ever find [them]." Iroh vanishes before they can ask him what he means, but Tenzin realizes where they can find Jinora.
As Vaatu looms over Korra, suspending her in the air with his vines, she uses the Avatar State to augment her firebending and escape his trap. Renewing her attack, she knocks him back with several blows and manages to trap him within an elemental sphere, moving to imprison him again in the Tree of Time. While this happens, Bolin and Mako are ambushed and subdued by Desna and Eska outside the portal, enabling Unalaq to walk back into the Spirit World.
Tenzin resolves to antagonize the dark spider spirit they encountered before, believing it can lead them to the prison where Jinora is being held. The spirit captures them and drags them to a wide chasm in the ground, its floor obscured by a thick white mist. As it dumps the siblings into the abyss, the spirit declares that they will never escape the Fog of Lost Souls.
Just as Korra is about to lock Vaatu back inside the Tree of Time, she is hit in the back by a stream of water, enabling Vaatu to break free of her hold. Dazed by the unexpected attack from Unalaq, she is defenseless against his next attack and is thrown back to the ground.
As Desna and Eska drag an unconscious Mako and Bolin away from the portal, the brothers wake up and manage to surprise the twins. Sprinting through the portal, they are shocked to find Vaatu looming over the Tree of Time and Korra lying on the ground. Before they can reach her, however, they are trapped in ice by Desna and Eska. As Korra scrambles to her feet again, she finds Vaatu hovering next to Unalaq. In an attempt to keep them apart, she uses the last of her power to assault her uncle with a fire blast, though he easily dissipates it. Unable to do anything else, Korra watches helplessly as Vaatu fuses with Unalaq permanently, using the energy from the spirit portals to cement the bond. Unalaq, now a Dark Avatar, declares the beginning of a new era for spirits and humans, led by himself as the new Avatar. Korra counters that she is the "old Avatar" and that her era is not over yet, before clashing in another battle with her uncle.
Beginning to walk through the mist, Bumi wonders the effectiveness of the barless prison as they could just walk out. Tenzin explains that, according to an ancient text, the fog itself is a spirit that can infect the mind of humans and imprison them in their darkest memories, causing them to lose their sanity. Just as a horrified Kya wonders how long someone could be trapped in the fog, Zhao passes by, repeatedly muttering to himself that he is "Zhao the Conqueror, the moonslayer" and that he will capture the Avatar. Seeing Tenzin, Zhao mistakes him for Aang and attacks him, prompting Kya and Bumi to separate the two. Knocking him back with waterbending, the siblings run off, leaving Zhao to disappear into the fog, shouting his desire to defeat the Avatar echoing through the prison. As a precaution against wandering off, Tenzin uses his sash as a rope to tie Kya and Bumi to himself, noting that if they can stay together, they will find Jinora.
Korra and Unalaq soar through the Southern portal, moving their fight into the physical world to the South Pole. Coursing over the icy tundra, riding an air and waterspout respectively, the two Avatars trade blows, barraging each other with the elements they command. Unalaq eventually manages to usurp Korra's ice shield and use it to encase her in ice. Throwing her onto the ground, the ice shatters, leaving her dazed and vulnerable to be trapped in a fissure in the permafrost. Attempting to crush the Avatar, he orders her to give up. As the ground closes up over her, Raava reaches out to Korra. Telling her not to Vaatu win and to give in to ten thousand years of darkness, Raava reminds Korra that she is the Avatar. Reinvigorating herself by entering the Avatar State, Korra blasts her way out of the hole with firebending. Telling Unalaq that his victory is impossible, they resume the battle.
In the Fog of Lost Souls, Bumi and Kya begin to suffer the effects of the fog; Bumi believes himself to be surrounded by cannibals, and Kya has the impression that she has no family. Stricken by panic and terror, the two untie themselves from the rope connecting the three together, and flee in opposite directions. Tenzin attempts to dispel the fog with airbending, but fails.
Still trapped in ice near the Tree of Time, Mako pleads with Desna and Eska to release them, trying to explain that Unalaq is "an evil monster". Unconvinced, the two refuse to release the brothers, but Bolin begins to sob; when a curious Eska questions him, he tells her that he is distraught over the fact that the untimely end of the world will prevent him from being with Eska again. He apologizes to Eska for leaving her, expressing regret that they were unable to "rekindle the dying ember" of their love into a "big fire of love flames". Moved by Bolin's show of emotion, Eska kisses him and releases the brothers. Once out of earshot of the others, Mako compliments his brother's acting abilities, with Bolin somewhat skeptical that his show of emotion was completely acting. Desna claims that the two will "certainly perish". As they emerge into the physical world, they witness both Korra and Unalaq battling each other in their Avatar States. Korra is able to bring Unalaq down, but when their struggle pulls them within arm's length of each other, Vaatu leaves Unalaq's body and tears Raava from Korra's body, and she falls to the ground, most of her energy gone. Before Vaatu enters Unalaq again, the waterbender traps Raava in a shell of ice, grinning victoriously.
In the fog, Tenzin's fear, that of failing to preserve his father's legacy, begins to consume him. As he struggles to ward off his dark thoughts, a vision of Aang appears before him. Tenzin, hanging his head in shame, profusely apologizes to his father for not being like him; to Tenzin's surprise, Aang agrees that his son is not like him. Aang elaborates, telling Tenzin that he made a mistake in trying to mirror his father in the first place, as it caused him to develop a false perception of his identity. The old Avatar finishes by saying that his son is not him, and that, as a separate person from Aang, he should not be Aang, but rather be himself. The vision vanishes in a cloud of smoke, and as Tenzin, realizing who he is for the first time, repeats his father's message to himself, the fog retreats from him, allowing him to find Jinora and his siblings and lead them from the canyon. As they exit the valley, the fog covers the valley once again; their heads free of the fog's influence, Kya and Bumi regain their sanity, while Jinora expresses joy that her father has found her.
Despite their efforts to save Raava, Bolin and Mako are easily defeated by Unalaq, leaving the weakened Korra to watch as Unalaq attacks the light spirit. With every blow against Raava, Korra's connection to her past lives begins to break, and after several focused attacks, it shatters completely as Unalaq destroys Raava's physical form; in a vision, Korra sees Avatar Wan, her last remaining past life, disappear. As Vaatu defeats Raava, Jinora senses the sudden imbalance between dark and light; declaring to Tenzin, Kya and Bumi that Korra needs her help, she leaves them with a spirit to guide them out of the Spirit World and disappears.
Desna and Eska step through the Southern spirit portal to find Unalaq and Vaatu, unopposed by Raava's presence, growing into a massive dark spirit. The Dark Avatar proclaims the beginning of ten thousand years of darkness, before using the spirit lights to leave the South Pole and make his way to Republic City. His departure creates a shock wave renders Mako, Bolin, Korra, Desna, and Eska unconscious.
- Written by:
- Directed by:
- Janet Varney - Korra
- David Faustino - Mako
- P. J. Byrne - Bolin
- J. K. Simmons - Tenzin
- Adrian LaTourelle
- Jeff Bennett - Radio broadcaster
- Richard Riehle - Bumi
- Aubrey Plaza - Eska
- Aaron Himelstein - Desna
- Lisa Edelstein - Kya
- Kiernan Shipka - Jinora
- Also starring:
- Main article: Transcript:Darkness Falls
- Zhao was brought to the Fog of Lost Souls after he was taken by La in "The Siege of the North, Part 2".
- Jinora recalls that the last thing she remembered was being taken by dark spirits, namely by a dark dragonfly bunny spirit in "A New Spiritual Age".
- Bolin apologizes to Eska for leaving her at the altar in "Civil Wars, Part 2".
- The light spirit Jinora gives Tenzin to guide him and his siblings out of the Spirit World is a glittering butterfly, similar to the first spirit she and Korra encountered after entering the Spirit World in "A New Spiritual Age".
- Korra pulling Unalaq in with water tendrils is reminiscent of Katara using the same technique against Azula in "The Crossroads of Destiny".
- On November 15, 2013, Korra Nation challenged the fans to reblog a short video posted by Janet Varney on Korra Nation's Tumblr ten thousand times within twelve hours of its posting; if they did so, "Darkness Falls" and "Light in the Dark" would be available on Nick.com at midnight that same night. The task was completed by Korra fans within two hours, thus prompting the unlocking of the episodes.
- Iroh last saw Aang and Katara's children circa 131 AG.