A new novel by Sophie Hannah is cause for great celebration, at least as far as I'm concerned. I loved her three previous novels - "Cordial and Corrosive" (probably my favourite), "Gripless" and "The Superpower of Love" - and am also a big fan of her poetry. So I was absolutely delighted to get my hands on this latest novel.

"Little Face" is, however, something of a departure from Sophie's previous work. It's described on the jacket as a "psychological thriller" and is clearly packaged and marketed as such, with one of those cover pictures - common to missing-child thrillers - of an empty corridor with an abandoned toy at the end, and the tagline, "It's every mother's nightmare...". Now, I like a nice psychological thriller as much as anybody, but this generic image was sufficiently different from Sophie's previous quirky novels to discompose me slightly. I still couldn't wait to read it, though.

The novel has an intriguing premise. Alice Fancourt, homeopath, wife of David, daughter-in-law of the unbelievably controlling Vivienne - in whose house they live - and new mother of two-week-old Florence, makes a brief trip out of the house for the first time since Florence's birth. When she returns, all hell breaks loose - there is a baby in Florence's cot, wearing Florence's clothes, but, says Alice, that baby is not Florence. Well, the words "post-natal psychosis" may immediately spring to mind, and indeed Alice is automatically assumed to be off her head by many of those around her, notably her husband. After all, she has just survived a traumatic birth, and has a history of depression, as David - not, it is fair to say, the world's most supportive husband - is quick to point out to the police. But naturally, the truth is far more complicated than that. And when both Alice and the baby go missing, the situation becomes even more urgent...

The novel is told, in turns, from the points of view of Alice and of the detective investigating the case, Simon Waterhouse, who becomes a little too involved in the case - falling foul of his superiors in the process. Sophie Hannah builds the suspense well and her characters are rounded and skilfully drawn. The apparent - and deeply disturbing - change in the character of David as the novel progresses is an alarming illustration of the dangers of marrying someone you don't really know all that well, and contributes greatly to the threatening atmosphere surrounding Alice.

As I mentioned, "Little Face" - the name Alice uses for the not-Florence baby - doesn't appear to bear much resemblance to Sophie's previous novels ("Cordial and Corrosive", for example, was an academic satire told from the point of view of a driving instructor). It's told in a more conventional format, for a start, and the humour which was evident in much of her previous work is largely absent here - after all, there aren't too many laughs to be derived from the situation in which Alice finds herself - although there are odd flashes of it. The book seems to have been marketed to appeal to a different audience; there is no mention of the author's previous novels in the brief biography on the back cover. This is borne out by the packaging and the "every mother's nightmare" tagline. (I'm not sure how true this is, actually. I worried about lots of things as a new mother, but the possibility that someone might come into my house and exchange my baby for a close replica was not one of them. Though probably only because it never occurred to me as a possibility.)

The novel has an absolutely cracking twist at the end. The kind that forces you to instantly re-evaluate everything that's gone before. This is handled really well and I definitely didn't see it coming, although with hindsight the clues were there.

I would highly recommend this and other work by Sophie Hannah. While the quirkiness of her previous novels may not appeal to everyone, they're definitely well worth checking out - if your taste is anything like mine, you have a treat in store! (Though I'm a bit alarmed that many of the "Little Face" reviews have referred to her "first novel" - there seems to be a campaign under way to expunge reference to her previous ones, which is unfortunate.) "Little Face", while clearly situated within the psychological-crime genre, manages to transcend this to some extent, and the novel stayed in my mind for a considerable time after I had read it.

Hodder & Stoughton hardback, 416pp, cover price £18.99. (Or try the library...) The paperback is out on 24th August 2006. I also learn from www.sophiehannah.com that a new novel and a collection of short stories are due for publication in 2007. Hurrah!