This is my favorite Ashley Zacharias book so far, and I've read most of them. The protagonist is very relatable, the dilemma she finds herself in is very believable, and the resolution follows very naturally from the actions the reader sees her take. There is some kinky stuff here, but it is in service to the story rather than the reverse.
If I were reading a draft of the book, I'd make two suggestions to the author:
1. Make the consequences of the heroine's realization that she gets sexually excited when she gets ordered around a bigger part of the plot (make it add to her dilemma; does she even want to escape from her situation?) and leave open as long as possible the possibility that she could choose to stay on this path, and
2. Make the story climax more elaborate; have some elements of it go awry, so the heroine has to adjust her plans (and demonstrate her genius once again) to make her solution work. As it is, the story climax is a bit anticlimactic (at least compared to our expectations at that point).
But those weak points don't detract much from this book. The pleasure of the book comes from seeing the main character grow in character and inner strength under the pressures of a horrible situation. Her increasing awareness of the power of her own sexuality eventually morphs into a realization that, contrary to her views at the beginning, her situation is not hopeless and she is not powerless to affect her fate. This is a common Zacharias book element, but we generally only see it happening over the course of several books. I think seeing it happen over the course of a single book makes it better.
(reviewed 2 days after purchase)