The Irish aristocrat -- cum -- plotter of world domination returns for a third round, and the kid's still got it. (For those not familiar with past romps, young Fowl discovered an elf-dwarf-centaur-sprite underground society, which he's been exploiting ever since.) Now the 13-year-old has invented a high-tech cube from fairy gizmos that renders all communication technology obsolete. When the cube is stolen, Fowl needs his old spritely friend/nemesis, Holly Short, to get it back. Colfer's characters -- cantankerous elves, a flighty girl bodyguard, and a dwarf who shoots gas balls out of his bum -- are still silly and saucy, and Fowl's foul deeds continue to tweak his conscience in an endearingly unsoggy way. This ''kids' book'' is up there with Harry Potter. In fact, Harry had better watch his back.