For the rest of her life, Charlotte Cleve would blame herself for her son's death because she had decided to have the Mother's Day dinner at six in the evening instead of at noon, after church, which is when the Cleves usually had it. 

Gazing backwards and forwards at the same time, yet so headlong in its rhythm that we are pulled into an intense present moment just to keep up with it, The Little Friend begins.

What will follow will be a story both beguiling and evasive, leading us down apparently obvious paths that take us nowhere and forcing us back to where we began. Like a conventional thriller, The Little Friend begins with a dramatic event: the murder of a child. Unexplained as this murder is, the reader cannot be blamed for hoping there will be some revelation in the narrative. The first sentence, though, is enough to warn us - or else to shrug at us on a rereading, whispering, 'Well, I told you so' - that this is not really what the book is about.

Because, you see, the son's death, dramatically announced, is actually not the main subject of the sentence. Contained in a mere three words - 'her son's death' - it is dwarfed by the run-on explanation of the minutiae of family rituals. In a breathless rush, barely broken up by commas, we hear all the details: not just a dinner, but a Mother's Day dinner; the only commas supplied are to frame the aside of 'after church', a detail entirely concerned with the normal routine, the Cleves' relationship to the broader community, rather than the death of the boy.

It's almost as if we hear Charlotte herself lamenting, with the unspooling accumulation of detail of spoken rather than written English - especially when the writer is so poised a stylist as Tartt. And the effect is splitting: the lengthy recitation of Cleve customs dwarfing the death of the son tells us, in a cool, understated way, where Tartt's focus is going to lie. She is not studying Robin's death, but Cleve family life. His death will harrow it, but customs and habits and personalities will survive him, and that's what we're going to be looking at. In effect, it's a quiet hint that we will have no explanation for Robin's death because it's not the subject, even of the sentence that announces it.

The Little Friend is a book that approaches its subject slowly, and it's only deep into it that it becomes clear. Notably, for instance, the main protagonist of the story, the child Harriet, is absent from this sentence, from her mother's thoughts and feelings, almost absent from the whole first chapter. The following pages will wind through various members of the Cleve clan before finally settling on Harriet, and many more chapters before we'll see through the eyes of Danny Ratliff, the second protagonist. The thematic centre of the story is most clearly expressed through Harriet's kindly old great-aunt's sad remark, 'It's awful being a child ... at the mercy of other people.'  And deeply true though this is of Harriet's life, in fact it's not just childhood that puts you at people's mercy: adult Danny is just as much at the mercy of his own family, and his capacity to act against it will prove as fruitless as Harriet's search for Robin's killer.

But even more than that, we have this first sentence: a mother blaming herself for her son's death because she has made a tiny deviation from family ritual. Nobody else is blaming her, but the pressure of custom, of shared expectations, bears down on her with a crushing burden of guilt. Tartt is a great chronicler of the horrors of small frictions and everyday aggressions, and here in the first sentence, we see this horror in its purest, most pervasive form. The story that follows will mostly be about the Cleve family, about the nature of the Cleve family, but it will be about family in a broader sense ... and what we see hinted here in this first sentence is that, intentionally or not, explicitly or not, living together puts all of us at the mercy of other people. Robin falls first and hardest, but nobody will come out unscathed.