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). For a start, leprechaun technology is more advanced than our own. Add to that the fact that Holly is a true heroine and that her senior officer Commander Root will stop at nothing to get her back and you've got the mother of all sieges brewing!