The Opal Deception (artemis Fowl, #4)

The fourth installment in Eoin Colfer's Artemis Fowl series is set in a world where fairies, elves, dwarfs, and other magical species live in a technologically advanced civilization beneath the earth's surface, governed by the Lower Elements Police (LEP). In previous books, fourteen-year-old Irish criminal genius Artemis Fowl clashed with and ultimately aided the fairy world, but as a condition of their last cooperation, the LEP wiped all fairy-related memories from Artemis's mind and those of his bodyguard, Butler.

The story reveals that Opal Koboi, the pixie billionairess who bankrolled a failed goblin rebellion, is not truly comatose. For nearly a year she has occupied a cell at the J. Argon Clinic in Haven City, appearing unresponsive while secretly plotting in a self-induced meditative trance. Opal seeks revenge against the four individuals responsible for her downfall: LEP Commander Julius Root, Captain Holly Short, the centaur technical consultant Foaly, and Artemis. Before her imprisonment, she installed two loyal pixie operatives, the twin brothers Mervall and Descant Brill, as the clinic's janitors and commissioned an illegal clone of herself. Three months before the main events, the Brills swap Opal with the clone and smuggle her out undetected.

Meanwhile, Artemis and Butler travel to Munich to steal The Fairy Thief, a legendary lost painting by the French Impressionist Pascal Hervé, from a bank vault. They succeed, retrieving the painting in a sealed Perspex tube, unaware that Opal's agents have planted a tracker inside it.

In Haven City, Holly learns she is about to become the first female major in LEP Recon, the force's reconnaissance division. Root persuades her to accept, but their plans are disrupted when General Scalene, a goblin war criminal, escapes from prison. Root and Holly enter chute E37, a disused magma vent, to confront Scalene and find him mesmerized, strapped to an explosive device bearing Opal's face on a screen. Opal has jammed their communications, and when Root reaches for Scalene, mechanical bonds cinch the bomb to the commander's chest. A sixty-second countdown begins. Opal taunts Holly with a supposed weak point that could disable the bomb. Root orders Holly to leave, but she fires at the spot. Opal reveals there was never any weak point; she invented it purely for cruelty. The device detonates, killing Root instantly and blasting Holly into the chute.

At the Kronski Hotel in Munich, Butler detects a fairy-manufactured missile homing in on the tracker. He grabs Artemis and leaps from the third-floor window moments before a bio-bomb, a weapon that kills all living tissue without structural damage, detonates in the empty room. Holly arrives too late to prevent the blast. A second bio-bomb confronts her on the rooftop, and Opal gloats about her plan to expose the fairy world to humans. Holly contains the blast under her LEP helmet and outflies the lethal light, but the helmet is destroyed, causing the LEP to register her as dead. Holly heals Artemis's broken ribs with her last sparks of magic and flies him to a hidden surveillance pod in Dublin, leaving Butler behind because he is too large to carry.

Commander Ark Sool of Internal Affairs, a humorless gnome, takes control of the investigation. Without audio, the footage appears to show Holly shooting Root. Foaly protests but is overruled. In the Dublin safe house, Holly explains the fairy world to the amnesiac Artemis and recounts their shared history. Though he accepts the facts logically, the mind wipe prevents true recall. He demands a fee of one metric ton of gold to help, which infuriates Holly. Opal and the Brill brothers track them down, blast through the pod's wall, and stun both Artemis and Holly.

Mulch Diggums, a kleptomaniac tunnel dwarf being transported back to prison, hears of Root's death and Holly's suspected guilt. Convinced of Holly's innocence, he escapes the subshuttle, an underwater fairy transport vessel, by exploiting his unique dwarf physiology and makes his way to Fowl Manor. There, Butler discovers the gold-plated computer disk Artemis entrusted to Mulch before the mind wipe. A video on the disk reveals Butler's secret first name, "Domovoi," triggering the instant return of all his suppressed memories. Butler and Mulch piece together Opal's plan and head underground.

Opal transports Holly and Artemis to the Eleven Wonders, a derelict fairy theme park overrun by trolls, massive shaggy carnivores with venomous tusks. She sprays the captives with troll mating pheromones and locks them inside an exhibit. Holly and Artemis mask the scent with mud and use a waterproof video pod's bright screen to repel the light-sensitive creatures while climbing to the roof. Butler and Mulch arrive to rescue them. Mulch, who obtained an LEP shuttle with the help of Chix Verbil, a sprite officer whose life Holly once saved, unleashes a blast of dwarf flatulence powerful enough to collapse the trolls' nervous systems. The four escape in the shuttle.

Artemis plays his self-recorded video diary from the disk and recovers all his fairy memories. He waives his gold fee, feeling genuine grief for Root. He explains Opal's larger scheme: Giovanni Zito, a mesmerized Italian environmentalist, has launched a probe encased in molten iron descending through the earth's mantle. If Opal detonates shaped charges to crack the wall between the iron mass and a fairy transit chute, the molten metal will flood Haven City and expose fairy signals to human detection.

Foaly independently discovers the clone by scanning its retinas with a Retimager, a device that reveals the last image recorded on a retina. The image is Opal's own face, proving the patient is a body double. Foaly persuades Commander Sool to dispatch an attack shuttle. Holly locates Opal's stealth shuttle by scanning for a void in ambient gases, and while Butler drops grenades as a distraction, Mulch tunnels into the hull and hides both shaped charges in Opal's booty box, a secret compartment lined with stealth ore, a signal-blocking material that shields objects from remote triggers.

Artemis taunts Opal over a planted communicator, eating her prized chocolate truffles to provoke her into checking the booty box. Opening the lid exposes the charges to the detonation signal her crew has been broadcasting continuously, and they activate. Opal ejects the Brill brothers and launches her own escape pod, firing two heat-seeking missiles at Holly's shuttle. The charges detonate harmlessly well above the critical depth. Holly evades the missiles by cutting the engines and free-falling until the heat signature fades. Major Trouble Kelp, piloting the LEP attack shuttle, destroys both missiles and escorts the group to Haven.

A tribunal clears Holly of all charges. Mulch's charges are also dropped. Holly watches Root's recycling ceremony, the fairy equivalent of a funeral, on a screen, barred from attending by Sool. Furious, she tears off her LEP badge and quits, announcing she will become a private investigator with Mulch as her partner. She slips a fairy communicator into Artemis's pocket before Sool has him and Butler tranquilized for transport home. Opal is captured a week later at an Italian vineyard, where a human pituitary gland she had surgically implanted to grow taller and pass as human has overpowered her fairy magic, leaving her without her mesmer ability and trapped doing manual labor.

Artemis wakes at Fowl Manor with all his memories intact and resolves to use his talents for good. Holly calls with her first PI case, and Artemis agrees to consult. He hears his parents arriving home and runs downstairs to his mother's open arms. An epilogue, presented as an Irish Times article, reports that The Fairy Thief has been anonymously mailed to the Louvre, accompanied by a typed note: "More to follow."