Artemis Fowl series by Eoin Colfer
Twelve-year-old Artemis Fowl is a millionaire, a genius—and, above all, a criminal mastermind. But even Artemis doesn't know what he's taken on when he kidnaps a fairy, Captain Holly Short of the LEPrecon Unit. These aren't the fairies of bedtime stories—they're dangerous! Full of unexpected twists and turns, Artemis Fowl is a riveting, magical adventure.