Artemis Fowl is a novel about a twelve-year-old boy prodigy named Artemis Fowl, who runs a crime syndicate. After discovering the existence of fairies and decoding their holy book, Artemis manages to kidnap Holly, a crime-fighting fairy, holding her hostage in his mansion and demanding a metric ton of gold as ransom. After various mind-games and tricks with the fairy police who are trying to retrieve Holly, Artemis receives the gold and releases Holly.
Artemis Fowl II is the twelve-year-old son of an Irish crime lord, Artemis Fowl I. He is a child prodigy, who has dedicated his life to criminal activities. He leads the Fowl criminal empire, which has been established by his family for generations. After significant research, Artemis believes that he has confirmed the existence of fairies. He tracks down an alcoholic sprite posing as a healer in Ho Chi Minh City, Vietnam, and travels there with his bodyguard Butler to obtain from her The Book of the People —the Fairy holy book that is written in Gnommish.
Meanwhile, Captain Holly Short of the Lower Elements Police is tracking a rogue troll that has managed to reach the surface of the Earth from Haven city, thousands of feet underground. Assisted by the technically minded centaur Foaly and LEPrecon commander Julius Root, she incapacitates the troll.
Artemis decodes the Book using translating software, and in the process, learns the specifics of the ritual fairies use to replenish their magic: take an acorn from an ancient oak tree near a bend in a river under the full moon and plant it elsewhere. Artemis and Butler track down 129 possible locations for the ritual and start a stakeout, they discover Holly performing the ritual. Butler tranquilizes Holly with a hypodermic dart gun.
A LEP retrieval team is sent to scout Fowl Manor. Using their 'shielding' ability, which allows them to vibrate faster than the human eye can follow, the team enters the manor grounds. Artemis had anticipated this, however, and installed a camera with a high frames-per-second rate, allowing him to detect the threat by freezing the image. After Butler incapacitates the intruders, Root decides to lay siege to Fowl Manor using a time-stop and enter negotiations. Artemis reveals the ransom demand: one metric ton of 24-carat gold. Artemis also reveals his knowledge of the time-stop and claims that he can escape it. An analysis by LEP behavior experts determines that Artemis is telling the truth.
The attempts to gain entry to the manor continue as the LEP recruit an infamous criminal, the kleptomaniac dwarf Mulch Diggums to break in. Fairies are forbidden from entering human dwellings without permission, but Mulch has broken this rule so many times that he is immune to the adverse consequences. He tunnels underground to reach the house while Foaly feeds a loop to the manor surveillance system, allowing Mulch to freely explore. Mulch accidentally locates a safe containing Artemis' copy of the Book, finally revealing to the fairies the source of Artemis' knowledge, which he had led them to believe he had acquired from a truth serum administered to Holly. The Fairy Council, deciding that nothing is working, promotes a lieutenant called Briar Cudgeon to Acting Commander, temporarily usurping Julius Root. Meanwhile, Holly Short cracks through the concrete of her cell, finding fresh dirt, and completes the ritual with a smuggled acorn. Having regained her magic, she escapes into the main house.
Cudgeon decides to release the troll Holly captured earlier into the mansion to force Artemis to allow the fairies to enter and subdue the troll. This backfires, as Butler, aided by Holly's healing powers, defeats the troll. The Fairy Council subsequently strips Cudgeon of his post.
Artemis is finally granted the ransom. The gold is sent in, and Artemis asks Holly for a wish: to cure his mother's insanity— she has been living in her bedroom, driven mad by the loss of her husband. Holly grants the wish at the cost of half the gold. The LEP decides to send in a 'blue rinse' – a biological bomb that kills all organic life — to eliminate Artemis and allow for the retrieval of the gold, but this fails when Artemis escapes the time-stop by drugging himself and his comrades with sleeping pills.
Having survived until the end of the time stop, the LEP is bound by law and leaves the remaining gold and departs. At the end, Butler demands an explanation as to how Artemis came up with the idea of using sleeping pills. Artemis explains that he had gotten the idea from old fairy tales, in which human characters never wake up at an inopportune moment for the fairies, and had guessed that time-stops were the reason. Artemis finds his mother has fully recovered from her insanity thanks to Holly's magic.