The third book in the Spiderwick Chronicles.
Things at the Spiderwick estate are out of control. As if being attacked by goblins and a bridge troll wasn't enough, now the house boggart, Thimbletack, is out to get Jared.
Meanwhile, Simon has a very hungry griffon recuperating in the carriage house, and Mallory is convinced that the only way to stop the madness is to destroy Arthur Spiderwick's Field Guide. But with all kinds of creatures after them, the Guide seems to be the only protection the Grace kids have. If they could just figure out the faeries want it so badly...