The Last Guardian - Eoin Colfer

Opal Koboi, the power-crazed pixie, is plotting to exterminate humankind and become fairy queen. If she succeeds, the spirits of long-dead fairy warriors will rise from the earth, inhabit the nearest available bodies, and wreak mass destruction. But what happens if those nearest bodies include animals, or two curious little boys named Myles and Beckett Fowl? Can Artemis and Holly stop Opal and prevent the end of the world?