I bought this book for my 12 year old daughter, and was disappointed when I flipped through the pages. I noticed that the author used repeated references to R-rated movies and did not find that to be appropriate for a book directed at kids/teens. My daughter has not seen Misery, The Shining, Aliens, or Collateral Damage. Those were the references I saw just from flipping through. Could be more. The author uses characters from these movies to describe things in this book assuming kids have seen them. Returned this book for something better.
I read this book because the mention of time travel in the description intrigued me. Unfortunately, this element doesn't show up until 2/3 through the book, and even then, it's not very extensive.
I also really didn't like the portrayal of gender in this book. The male characters get to go on adventures and try to save the day, but the female characters are always damsels in distress who are purposefully kept out of the loop.
Yet, it's great in the chiller-thriller department. Most tween and teen boys would probably enjoy this book a lot more than I did.