Lee seems like the perfect man, good looking, charming, brilliant in bed, and makes Cathy the envy of all her friends; Gradually though she begins to realise that he's possessive, dominating, controlling but she's the only one who can see Lee's dark side.
There are loads of books about domestic violence, about damaged women struggling to recover from their ordeals, about women being stalked but this book is several cuts above the majority. It's well written and paced, there aren't any flat bits and it's genuinely frightening in some parts. The tone is always quite restrained so instead of being made to jump in shock as happens in many books the menace and fear grow slowly and stay with you.
Cathy is utterly convincing as a character; she could be any of us, mired in a situation which she realised about just a little too late to extract herself from, and who then hits rock bottom and tries to drag herself upwards. You're right there in her head while she tells her story and empathising is the word for it, I was so involved with her that my heart rate started to speed up at certain tense points.
Secondly it's written in dual time. Four years before when she met Lee and now, as she starts to try to heal herself and realises that Lee might be looking for her again. It means that you get loads of small, and occasionally much bigger, cliff-hangers, sometimes operating simultaneously in both time lines which ramps the unputdownable factor hugely! I was up to 1.30 reading it two nights running.
I don't normally like psychological thrillers of this kind and only read this one because I'm hearing the author speak at a literary festival in a couple of weeks, but this has got to be the best thriller I've read this year. Highly recommended.