This book is a very good reason never to take part in a medical trial.Although it starts off fairly slowly the pace picks up towards the second half.The concept brings to mind how trusting we are that no other person means us harm and what we are willing to go through to make money. Even when our gut instinct is screaming no.The prequel didn't fit with the concept of this novel at all. I was expecting the author to follow the path of one of the characters revealing himself to be the serial killer from the prequel. Instead I think that idea got lost in the midst, perhaps to be used at a later date and in a different book.The build up of paranoia between both the patients and the staff was well portrayed. Often the reader is unaware whether the patient is dreaming or experiencing the events.I felt that the book left some questions unanswered. What was the purpose, who and how did it all come together? In what way was the neighbour involved or wasn't she. The violence is quite visual at times. In the last few chapters the story went from thriller to violent horror, almost at random without any real linking to the plot. This detracted from the good psychological warfare going on in the first half of the book.I received a free copy of this book for my review.