I found this book utterly compelling and literally impossible to put down. The plot has already been discussed here so I won't re-hash that. Suffice it to say that this is a dark, convincing and terrifying account of how Catherine, a young, bright, girl-about-town is transformed into Cathy, self-effacing, crippled by OCD, and barely holding her life together.
The narrative unfolds in two parallel strands: Catherine's past, and Cathy's present - a format I usually find irritating, but it worked perfectly here.
Admittedly, there are some awkward coincidences: her new neighbour's profession, being spotted in London from a bus, the job advert - and a few points that don't really make sense (if you were in fear of your life wouldn't you change your name?), but the sweeping strength of the narrative enabled me to forgive them.
Be warned, this is very dark and disturbing, but also frighteningly plausible. The build up of fear is superb, and the menace is always hovering just out of sight. At the same time, this is an intelligent book with an awareness of sexual and gender politics, and has more important things to say than the average throw-away psychological thriller.
If you loved the early Nicci French books like
Killing Me Softly this is probably an excellent choice. Highly recommended.