I have to confess that this was the first novel I have read from this author, though I have watched and generally enjoyed her TV crime series 'Trial and Retribution' and - especially - 'Prime Suspect'.
The lead character is a female DCI whose boyfriend was a murder victim shortly before the timeframe of the novel opens. She has refused compassionate leave. New to her rank, her DCS (a former lover, who was responsible for her promotion) is trying to ease her into her new responsibilities gently, starting with a straightforward, open-and-shut case, followed by the case which is the core subject of the novel - a missing person case which looks as though it may turn out to be rather nasty - and in due course it does exactly that. In these circumstances I'd expect to feel at least some degree of empathy with the character, but that didn't happen. I certainly don't see myself as misogynistic, or even sexist, but I found myself disliking her.
A central element of the plot is the emerging Jekyll-and-Hyde personality of the 'missing person' but - for me, at least - the initial character portrayal is so sympathetic that the emerging depravity fails to convince. It's very hard to believe that someone so universally well-liked for so long could turn into a seriously nasty Mr. Hyde unless he was in the grip of a severe personality disorder, and that's never even hinted at.
Overall, though, after a slowish start the plot chugs along quite acceptably, and some chapters could fairly be described as page-turners. Unfortunately, there's no grand finale; the narrtative just seems to wind down to a conclusion as the enquiry progresses. That no doubt happens often enough in the real world, but it's not what we expect in a crime novel!
The surprise referred to in the heading is the relatively poor quality of the writing. The sentences are very short, and there's little attempt to evoke atmosphere, which seems odd from an accomplished writer of screenplays. I'm no fan of the see-how-many-big-words-I-know school of writing, but this novel is at the other end of the scale, using only a fairly limited vocabulary.
In summary, it's an undemanding and at times quite enjoyable read, but it could have been so much better.