Book Two Recap:
After the rising of the Red Lotus and the consequent battle in Republic City, Avatar Jahn and his friends took some time out to relax on Ember Island, courtesy of Prince Kazon. Jahn, filled with regret, struggles to come to terms with his actions after fighting the Red Lotus leader, Scarlett.
After a short Agni-Kai, Jahn reveals his true struggle: controlling the Avatar State, which has become unpredictable after absorbing the energies of the Soul Shaper. Determined to keep his mind busy, he returns home to Taku, fearing the Red Lotus invaded. The townsfolk are fine, however; saved by a mysterious group of powerful benders. Jahn greets Saall and Kuvu, his childhood friends, yet the rebuke him for killing another person.
Upon returning to Republic City, Jahn tries to contact the Northern Water Tribe by radio to query this new group, nicknamed the Spirit Eaters, but someone has sabotaged the radio signals to disrupt the impending Presidential elections. Team Avatar meet Tilia, a Metalbender, who joins their group and together, they deal with the individual responsible in Future Industries Tower, where Jahn Airbends naturally for the first time.
At the elections, Asami Sato wins the Presidency. When meeting the Avatar, she sends the Team to the Northern Water Tribe to investigate the Spirit Eaters, based on Jahn's instincts. Their blimp arrives within a few days and Jahn wastes no time. Chief Desna denies all knowledge of the group and threatens Jahn should he continue snooping. Prince Kazon, visiting, joins the Team.
Meanwhile, Anik, Tilia and Jinora meet Eska, who has gone into hiding and started a family with a man named Ornatok. Realising Desna is hiding something, Team Avatar break into the Palace, fighting off guards and eventually finding a tunnel under the throne, which leads to a secret base deep in the mountainside. They find a hidden technique involving the destruction of spirits to steal their power and meet the man responsible for the Spirit Eaters. He escapes after a confrontation, but the base suddenly erupts with them all inside, causing a huge avalanche which crushes the Palace and kills many residents around, including Chief Desna.
Back in the spirit world, the lion-turtle is woken by angry spirits, demanding he act on their murders. The lion-turtle agrees to investigate, yet meets their rebellious leader, a spirit named Zhansha. The spirit threatens war and leaves, furious at the lack of action.
Team Avatar survive their near-death experience and hide at Eska's as Jahn is unconscious, having saved them with the Avatar State. As they are blamed for the tragedy, the Team decides to leave immediately; they head for the blimp while Eska confronts her husband Ornatok, who has allied himself with the Spirit Eaters. Eska drives him from her home, her wrath blinding, as Team Avatar evade the Chief of Police, who happens to be Anik's stern father, eventually gathering Jahn and escaping the Northern Water Tribe.
When Jahn awakes, he is disturbed by his own actions. Tilia comforts him and the two bond quickly. Jahn enters the spirit world to ask for help, yet the spirits there turn on him, angry at the recent deaths of their kind. As they fly onwards, a spy sabotages the airship, causing it to crash near the ruins of the Northern Air Temple. Nearby villagers care for them as they question the Spirit Eater, yet furious spirits attack the village and take revenge for their fallen. The Team is chased by a huge insect spirit until they eventually reach an airport further to the south.
There, Chief Pallaya of the Northern Water Tribe catches up and arrests Jahn and his friends. After a lengthy questioning, Jahn and the others break out whilst Anik finally bonds with his distant father. Prince Kazon, in a rare angry outburst, reveals he has a daughter, who has been taken and hidden from him. As Anik is escorted out, Team Avatar steals a royal plane and they head for Republic City.
Upon landing, they meet the lion-turtle, who informs the Team that the spirits are growing restless under Zhansha's sermons. Before they can investigate, various bomb threats split the team. Jahn and Tilia successfully stop theirs from detonating but spirits hijack the radios with a formal demand for the Spirit Eater's heads.
To find the culprits behind the terrorist activity, Jahn and Tilia are sent to investigate a nearby factory by President Sato and Chief Mako. Jahn's childhood enemy Saall, now an officer, tags along. They encounter Ornatok, now driven to desperate measures due to his exile, who attacks. As Jahn battles the Spirit Eaters, the rest of their forces attack Air Temple Island, hoping to destroy the Air Spirit Qi-Lóng, who has been resting atop the Temple. Jinora successfully drives away the attackers with the assistance of the other Airbenders.
Meanwhile, Jahn is trapped with Tilia in a machine after a short fight, close to death. To save them, Jahn gives in to the Avatar State after a quick kiss from Tilia, momentarily defeating Ornatok and his allies, as they flee back towards the inner city. Tilia is rendered unconscious, so Jahn says goodbye, in case he shouldn't return.
In the midst of Jahn's return, Kai reveals that Tenzin was kidnapped in the attack on the Air Temple. Jinora immediately searches for her father, scared for his safety, as Jahn consults his past lives on his next steps.
Anik and Kazon, also searching, fight their way through the spirit wilds near the spirit portal, having been assaulted by Spirit Eaters. Jahn and Jinora reach the portal first, encountering Ornatok and his Spirit Eaters. Demanding they step down, Jahn prepares himself for a fight. Zhansha and his loyal spirits emerge from the portal, facing down the smaller army of humans with aggressive intent.
Jahn is given a choice by Ornatok: stay and prevent the oncoming war, or flee to save Tenzin from being executed nearby. Still regretting Scarlett's death, Jahn chooses Tenzin; he and Jinora turn tail to save her father as the Spirit Eaters and spirits launch the worlds into war.
The Avatar immediately returns to the portal but he is too late. Both sides have either been killed or fled to the Spirit World and into the city. Kazon and Anik finally reach the portal as a small mob arrives, headed by Kuvu and Saall. They demand Jahn fixes his mess, so they formally banish him to the Spirit World until the war is over. Jahn agrees, fully aware of the disaster unfolding. He wishes his friends well and enters the portal, locking it behind him.
The rest of Team Avatar leave, determined to assist Jahn where they can, as the human and spirit worlds collide in war for the first time since before Avatar Wan…
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