Looking after my grandchildren is sharpening my understanding of story structure. The current craze around here is Hide And Seek. It works best when I hide and they seek because they’re terrible at hiding. Another adult has to help them find a hiding place but they can’t stay put in it for longer than a few seconds.

So most of the time they seek and I stand behind the door or crouch behind a chair. (I don't have to hide very well - they're not much good at seeking either.) Then I suddenly spring out and roar like a lion. This is the bit they love best. They know the roar is coming, they know I’ll be the one roaring but it still scares them silly.

It seems to me that the same principle is at work in that dependable genre of fiction, the thriller. It's just Hide And Seek for adults without actually having to get out of your seat. I’ve just finished reading Before I Go To Sleep by S J Watson and it’s as fine an example of spine-tingling story-telling as you could look for. The architecture of the plot depends on that old literary chestnut, amnesia. In this case a trauma has left the protagonist unable to form long term memories. So she wakes up every morning with no idea who the man in bed next to her is and has to learn her life story anew each day. But it’s more complicated than that, of course, because the life story she is being told is neither complete nor accurate.

It’s a terrific piece of writing, all the more impressive because it’s a debut. It always cheers me up when someone writes a novel that is beautifully crafted. It reminds me that stories are meant to be enjoyed not endured. I’m not saying I learnt anything new about myself from reading it, or about other people for that matter. It taught be nothing at all about the meaning of life. But it did keep me awake until the small hours desperate to find out what would happen next, waiting for the villain to spring from his hiding place and roar.