Opal Koboi opens the Berserker's Gate, a portal located on the Fowl Estate, in which dwell the spirits of fairy soldiers, the last victims of the Battle of Taillte, the final blow in the war that sent the Fairy People underground. Artemis, after his last session of being cured of Atlantis Complex, rushes to stop her along with Holly and Butler. They fail, and Opal opens the first gate, which releases the spirits of the warriors who begin to possess other people and animals around them, including corpses, animals, Juliet Butler, and Artemis's toddler brothers, Myles and Beckett. After escaping Opal and the possessed beings, they are helped by Mulch Diggums, and they attempt to stop Opal from opening the second gate, which destroys every human on the surface. While doing so, they battle (reluctantly) Artemis's possessed toddler brother Myles, who reveals to them Opal's plan after the fairy warrior spirit left his body. While they fight, Opal has also sent a dangerous fake present to Foaly's wife to make him suffer. Her plan fails because Caballine masters martial arts and Foaly comes to save her from goblins that Opal sent as well. Artemis and his friends fail to destroy the second gate with a laser he created, and Mulch saves them from possessed pirate corpses by riding the oldest troll in the world and knocking out most of them, causing the spirits of fairy warriors to leave their bodies to the afterlife. They then enter Fowl Manor where Artemis decides to sacrifice himself in order to stop Opal from opening the second gate. Foaly sends the clone of Opal that she created in the 4th book, and using her hand he is able to make the clone close the gates since the magic recognizes the clone's DNA as Opal's. Everyone in that area, including the spirits, immediately go to heaven, excluding Artemis, whose humanity and sheer willpower enables him to stay on Earth. Six months later, with the saliva that Artemis produced when he kissed Holly, they extract his DNA and make a clone of Artemis Fowl, which is then taken to the now overgrown gate. Artemis's spirit then takes control of the clone and he is alive once more.