Artemis Fowl by Eoin Colfer

Twelve-year-old villain Artemis Fowl is the most ingenious criminal mastermind in history. His bold and daring plan is to hold a leprechaun to ransom. But he's taking on more than he bargained for when he kidnaps Captain Holly Short of the LEPrecon (Lower Elements Police Reconnaissance Unit). This is a truly modern classic, first published in 2002.