I wasn't sure at the time of reading this if there was such a thing as a Jack Caffery 'Series', as The Treatment is only the second and at the time of its publication (2001) there was no specific information about a third, but one thing's for sure: You should read Birdman first - this sequel will simply make more sense if you know what has gone on before in the tortuous life of DI Caffery. Also, the relationship between Caffery and his girlfriend is important, and the pivotal points of that require a knowledge of their history of one year earlier. So these excellent novels should be regarded as Part 1 and Part 2, and it is strongly recommended that you read them in the right order. As things have turned out, the third in the Caffery series Ritual came out in 2008, so there was a seven year wait.
The author builds her second story around another touchy subject, that of organised paedophilia, but unlike that of the previous novel - necrophilia - it doesn't quite occupy the reader's central thinking in the same potentially off-putting way. That's not because Hayder dilutes the narrative in any way (she certainly doesn't) but because she builds upon the character development of Jack Caffery so faithfully that we are inclined to believe that this man really exists, we know what makes him who he is and we sympathise with him for the pain he's been through and continues to suffer. The twist, if it could be called such, is the ending - I'm sure that many readers will expect the nice and happy ending that Caffery deserves, especially as it is being built up for us out of the sight and mind of Caffery himself, so that we know something priceless that he doesn't. Hayder is confident enough to avoid the twee ending that, on reflection, would have been out of sorts with the mood and direction of both novels.
For me, the only oddity throughout the tale was the credibility of Caffery's immediate superior, a lesbian Detective Chief Inspector who seemed inclined to defer to Caffery's judgement throughout, and whenever they were out in the field together she tended to come over as a junior partner in spite of her well-drawn independent personality. This though is undoubtedly one of Hayder's greatest strengths : characterisation. Every single character is as individual as they are meant to be, when they talk they talk in their own specific style and not in the style of the writer (if that makes sense!), so that whenever any two characters are in conversation we know who is talking simply by the choice of words. This is a rare skill, in my opinion. In the majority of other novels, characters may be tall or short, black or white, male or female but there is often a sameness to their personalities especially when conversations are taking place; it can appear that everyone talks in much the same way, with similar attitudes, even similar accents. Mo Hayder stands above her peers in this regard, among others, in having an ability to draw pictures of people who are all unique in their own way. I am sure that this is a result of hard work and research on the part of the author and she should be commended for it.
As for tension, suspense and emotion, The Treatment has it all and more. It's a story that, as with Birdman, raises many questions along the way (typically "what the hell's going on?") and while I was keen to discover the answers, I didn't want the story to end. Usually I read books in short snaps, maybe two or three chapters at a sitting, but with The Treatment I devoured it in two days. I was thinking about it even when I wasn't reading it. It's memorable, it's moving and it may even be considered a landmark if only because it stands tall within a densely-occupied genre in possessing those strengths while very few others do. The subject matter is dark and unpleasant, at times shocking in its clarity and really not best suited to the younger reader; if books were given censorship ratings as films are, then this one would without question carry an 18 certificate.
As one who reads constantly, usually in the genre of crime fiction, I find that there are only a handful of books that I can describe in detail a year or two after having completed them. Both Birdman and The Treatment will not be forgotten in a hurry, and each one might be one of those rare examples of stories that I will want to read more than once. Mo Hayder has a unique talent and, provided you have a stomach for the emotions that her writing will surely stir within you, I recommend this tale very strongly. You have been warned.....