Artemis Fowl II, the 13-year-old criminal mastermind, has created a supercomputer which he calls the "C Cube", from the stolen fairy LEPrecon helmets confiscated by Butler in the siege of Fowl Manor. It far surpasses any human technology made so far.[1] Fowl meets Chicago businessman Jon Spiro in London to show him the Cube, in an attempt to buy a considerable amount of gold in exchange for keeping the technology off the market. However, Spiro ambushes and outwits Artemis and steals the Cube. In the process, Butler, Artemis' bodyguard, is shot by one of Spiro's staff, Arno Blunt.
Artemis' demonstration of the Cube inadvertently detects Fairy technology below ground, causing a shutdown of all equipment in Haven city. In response, Commander Root sends Captain Holly Short to London to find what the disturbance was caused by. She locates Artemis, who persuades her to revive Butler with fairy magic and the aid of cryogenics. The procedure saves Butler's life, but ages him approximately 15 years. Artemis reveals the Cube's existence to Holly and the LEPrecon's technical expert Foaly the centaur.
Jon Spiro, meanwhile, has commissioned a mob family from Chicago to capture Artemis to break the Cube's Eternity Code which prevents Spiro from accessing its software. One of its employees is the dwarf Mulch Diggums, who is sent along with the thug Loafers to Fowl Manor to do the job. Although Mulch is rumbled, Loafers is incapacitated by Juliet, Butler's little sister, who has just returned from a failed final test at Madame Ko's Academy, where Butler trained to be a bodyguard. After a discussion with Root, who gives them 48 hours before he sends in a full Retrieval team, Artemis comes up with an elaborate plan to retrieve the Cube from Spiro's office in Chicago, involving the use of Holly, Mulch and Juliet. Root demands a mind-wipe of the three humans after the job is done, so Artemis leaves Butler in Ireland to ensure their memories survive.
The heist is ultimately successful, with Artemis retrieving the Cube after tricking Spiro into entering a rival company's headquarters to steal their new products. The Chicago police immediately arrive to arrest Spiro and his associates, and Foaly wipes Artemis' movements from the CCTV. Holly and Juliet remove Artemis from the crime, and return with Mulch to Ireland. Although Arno Blunt escapes and tries to enter Ireland to kill Artemis, Butler has him detained and frightens him into confessing his crimes. Root then has the three humans mind-wiped, after Holly mesmerizes Artemis to see if there were any traces left to trigger his memories. Unbeknownst to all, Artemis has had Butler commission three sets of contact lenses to stop the process. Artemis' plan to retrieve his memories involves Mulch Diggums: Artemis has the date of the search warrant of Mulch's cave changed to the day after his first arrest, rendering all subsequent convictions null and void. Artemis then hands Mulch a gold medallion before his mind-wipe, which is actually a computer disc containing all of Artemis' memories. Although Mulch is incarcerated, he takes comfort in the knowledge that "together they will be unstoppable."
