I thought this whole series was a fun and entertaining read.(I haven't seen the movie.) Diterlizzi and Black really know their fairy lore and I thought it was a good introdution to same for young kids. They'll see some of this stuff, like looking through circular stones to see the fae, or iron-allergies, in 'older kid' (and grownup) fantasy books as they continue reading. I started reading these before they were all out and it drove me crazy! Sigh. I envy those that get to read them all in one go.
There are five books in this story, but they're so short they'd more like chapters in any other book.
1: Field Guide
2: Seeing Stone
3: Lucinda's Secret
4: Ironwood Tree
5: The Wrath of Mulgarath
If you like this, you should read 'The Fairy Rebel'. by Lynne Reid Banks (J Fic).