This books is truly amazing with the psychological aspects of victim/victimizer. It is really a good story about how a person can go from a strong, confident, motivational woman to a willing slave through some very real circumstances. What is truly makes this book work, is that it could very easily happen to anyone. If you read romance and erotica books, you know that there are many, that while intriguing, the chance of them happening are extremely slim. Many of those books, are a fantasy written on paper (don't get me wrong, I like those books too), but the fact this could easily be a true story, makes it all the more fascinating. For example, which movie would scare you more, Silence of the Lambs (which could easily happen) or A Nightmare on Elm Street (a pure work of fiction and fantasy).
I will say that if you cannot handle hardcore BDSM, this is not the book for you. This is true sexually slavery without any consent, at least in a way, and no safeword.