The Spiderwick Chronicles, Volume II, Book 3 'Lucinda's Secret' and 4 'The Ironwood Tree'

Book 3—Lucinda's Secret

Things at the Spiderwick estate are getting completely out of hand. If being attacked by a band of marauding goblins and almost eaten by a bridge troll wasn't enough, how Jared is being harassed by Thimbletack, the house boggart, and Simon has a very hungry griffin recuperating in the carriage house. Mallory is convinced that the only way to stop the madness is to chuck the Guide. But that's not an option. With all kinds of creatures after them, the Guide is the only protection the Grace kids have. If they could just figure out why all of Faerie wants the Guide. Only one person can help solve this mystery—their crazy old Aunt Lucinda.

Book 4—The Ironwood Tree

First a pack of vile, smelly goblins snatch Simon. Then a band of elves try to entrap Jared. Why is the entire faerie world so eager to get their hands on Spiderwick's Guide? And will the Grace kids be left alone, now that the Guide has mysteriously disappeared?