Before I Go To Sleep by SJ Watson

In case you're wondering why I've finished two books in the space of 24 hours, this is because I had to have some dental work done under general anaesthetic on Friday, which necessitated a great deal of waiting around on a hospital trolley and then a great deal of sitting on the sofa feeling sorry for myself with a face resembling that of the Elephant Man, or perhaps a character from Bo' Selecta.

Anyway - before and after my operation, I read Before I Go To Sleep by SJ Watson, a psychological thriller with a clever but potentially restrictive concept behind it: Christine, the narrator, is suffering from a severe form of memory loss that causes her to wake up each morning with no memory of the day before. Now 47, she can remember nothing past her early 20s. Every day, she awakes horrified to see her middle-aged self in the mirror and to find herself living with Ben, a husband she doesn't recognise, in a house she's never seen.

If this sounds rather limiting, don't worry. Watson gets round the issue of Christine's short term memory by having her write a journal every day at the suggestion of the mysterious Dr Nash, who calls her daily to remind her where it's hidden, and it's this journal that makes up a large portion of the novel and which Christine uses to piece together what's been happening to her over the previous days. And written on the first page, in large capital letters, are the words 'DON'T TRUST BEN'.

Before I Go To Sleep is a tense, claustrophobic read with a heroine in an almost unbearably vulnerable position, trying to piece together decades of her own life from scraps of conflicting information from people who, despite their claims to know her, might just as well be strangers. To make matters worse, Christine knows she's suffered from paranoia in the past along with her memory loss, and may not be an objective judge of other's motives. But despite Christine's necessary vulnerability, she makes a strong and complex heroine and certainly one who is not without flaws. Watson manages to build enough interest into her character to prevent her from becoming merely a damsel in distress.

The central mystery is whether Ben is withholding certain facts from his wife for some sinister reason, or whether he is desperately trying to protect her from reliving past traumas - and if so, what those traumas might be. Ben himself is largely presented by necessity as an average Joe trying to make the best of a difficult situation; he's neither pantomime villain nor saintly carer. There's also Ed Nash, Christine's doctor, who seems keen to encourage Christine to keep secrets, and we find ourselves questioning his motives too. Unfortunately, Dr Nash isn't a particularly well-drawn character and his blandness does nothing to add to the potential intrigue. This struck me as rather a wasted opportunity.

Although Before I Go To Sleep kept me turning the pages with increasing nervous tension right to the end, this really is a novel where you have to suspend disbelief. There are far too many convenient coincidences and the way certain red herrings are explained away at the end is irritatingly lazy; it's easy to pick holes in the plot, particularly as the story comes to its end. I'm also not sure how much of a 'twist' I think the ending really is, although whether this really matters is debatable.

Overall, though, Before I Go To Sleep is a cleverly-structured thriller with a convincing protagonist - I found it surprisingly easy to imagine myself in Christine's shoes, although there are times when it's hard to approve of some of the choices she makes. If you're prepared to put aside misgivings about the realism of certain aspects of the story and you're looking for a page-turner, you could certainly do worse than this one.