The SpiderWick Chronicles - MG

After finding a mysterious handmade field guide in the attic of the ramshackle old mansion they've just moved into, Jared; his twin brother, Simon; and their older sister, Mallory, discover that there's a magical and maybe dangerous world existing parallel to our own--the world of Faerie. The Grace children want to share their story, but the faeries will do everything possible to stop them....