I must say, the need to find out what happened was so intense that I had to finish this in one sitting. And I completely got the culprits wrong, even though I guessed at it a few times.
The protagonist was an interesting character. She sort of reminded me of the protagonist in Method 15/33, in that she was constantly trying to figure out a solution and how to manipulate others, but she does not have the gift of turning off her emotions, and I think the protagonist in Method 15/33 was a much better manipulator and planner in general (although the protagonist in this book managed to keep the police in the dark for most of it, which is pretty impressive).
I'm also pretty sure that there was something other than the mystery, like with the protagonist and Rebecca's best friend (Lizzie's) brother Jack, but to be honest, at the end when she was talking about what happened to Jack, I only had the vaguest idea. I guess I was just too caught up in the "what happened to Rebecca" mystery that I ignored everything else.
This is a creepy, disturbing book and you should only read it when you have a stretch of spare time ahead of you.
Disclaimer: I got a free copy of this book from the publisher via NetGalley in exchange for a free and honest review.