Sarah's brother mysteriously disappeared when she was a child - and she's been suffering the consequences ever since; resented by her alcoholic mother for not being able to remember exactly what happened that sleepy summer afternoon. Salt is rubbed further into the wound when a young girl later goes missing in the same town - a pupil of the now grown-up Sarah, teacher at a local private school.
Two stories are thus rolled into one, recounting both the past disappearance of Charlie and the present absence of Jenny, in alternating chapters. I've seen this device used before, not terribly successfully it has to be said (e.g. in Tobias Hill's 'Underground') but here it works quite well, because both tales are equally compelling.
I do agree with previous reviewer comments that Sarah's access to police information in the ongoing investigation stretches credibility a bit. And the lack of suspense is a disappointment (Wouldn't Sarah's mugging have seemed much more frightening if there had been some build-up to it or a stronger sense that she was being followed?). And though I quite enjoyed the plot twists, I did find myself a bit exasperated at the predictable need for yet another dramatic and violent finish (do all crime and thriller writers these days have TV and film screenplays in mind when penning grand finales?!).
That said it's a very easy and enjoyable read, if you can overlook the minor flaws. I completed it at one sitting on a train journey through France, and it certainly made the time fly, which must be an accolade of sorts.