After Mallory is kidnapped at her fencing meet, Jared and Simon search for her near an old quarry and find themselves amidst dwarves and goblins.
The Ironwood tree
This book might be part of the The Spiderwick chronicles -- bk. 4 series.

Tony DiTerlizzi: The Ironwood tree (2008, Simon and Schuster Books for Young Readers)
108 pages
English language
Published 2008 by Simon and Schuster Books for Young Readers.
Subjects
- Goblins
- Twins
- Brothers and sisters
- Dwarfs
- Caves
- Fiction