Coraline by Neil Gaiman
Coraline's a fairly typical girl with workaholic parents and little to entertain her on a rainy day. She amuses herself by counting things in her flat, and when she counts the doors she encounters a mysterious mirror world. It's all too good to be true at first. The mirror neighbors are interesting, the food is great and her other mother and other father pay attention to her. It seems like the perfect world, but things are not what they seem.
This book draws up older stories of children lured away by dark things. It's not too creepy, but it's just creepy enough. It's also a fast read, and was hard to put down. It's length and age of targeted audience with the addition of the great writing style makes it a great books to share if you're looking for a book for All Hallow's Read.
And after you've enjoyed the book (and possibly the film) I recommend enjoying the company of a Lalaloopsy doll.
Oh, look. It even has a circus mouse...