Christine wakes up every morning with no memory of who she is or why she seems to have aged two decades overnight. Her husband Ben must explain that she lost her memory in a car crash and each day Christine must come to terms with her condition all over again. But then she starts to be treated by Dr Nash, who encourages her to keep a journal. On the inside cover she has written 'Don't trust Ben!' As her memories start to return, Christine must learn that not everything around her is quite what it seems.Before I Go To Sleep is the very definition of a page-turner. I started it on Saturday morning and by lunch time on Sunday I had finished it. Watson cleverly gives you just enough clues in each chapter to keep you guessing and reading on to see if your guess was correct. He also makes things deliberately ambiguous so it's not too easy to guess where the plot is going (although I certainly had a vague idea of what might happen at the end). I've not read too many thrillers but have the feeling that the structure and pacing was perfect in this one.Christine's condition was dealt with very well too. In the hands of another writer the repetition of each day, of Christine waking up and not remembering anything, could have become very tedious. But Watson manages to keep the writing fresh and you end up feeling very sorry for Christine and rooting for her as she makes more discoveries.Despite all these strong points, I found Before I Go To Sleep to be only an average read. The majority of the book is written in diary entries and I just couldn't suspend my belief enough to accept that Christine would write dialogue, pages and pages of it, word for word in her journal. Watson told me it was a journal, but it read like a normal story so I never really bought into the concept. The end of the book annoyed me too, after all the horror and violence of the preceding events everything just fits together conveniently and nicely like nothing bad had ever happened. Life just isn't like that. And without going into spoilers, there were quite a few plot holes, especially surrounding Christine's release from a mental health institution.Verdict: Before I Go To Sleep is a fun, addictive read. Just don't think too much when you read it!