No and Me, By Delphine de Vigan

Little Parisian girl Lou Bertignac is 13 and very precocious indeed. With an IQ of 160 and two years ahead of her age-group at school, she spends her free time conducting scientific tests, developing theories about how the world works, counting and defining things – as a way of entertaining herself, and to take her mind off matters that would otherwise make her cry. Her family has been struggling to hold things together since the death of her baby sister, and her mother is distant.

Lou is fearful and vulnerable, and the last thing she wants to do is to give a presentation in front of her whole class. But then, watching people come and go at Austerlitz station (she likes watching the emotion), Lou strikes up a conversation with No, who is 18, pretty in spite of the dirt and her missing tooth, and homeless. Lou chooses the plight of the homeless as the subject for her class presentation, and No will be her interviewee.

But however much Lou may want things to fit her provable theories, to obey predictable rules, she will learn that "Things are what they are," that's all. Her teacher, M. Marin, describes her as "Utopian". (She thinks it's a compliment but goes to look it up in a dictionary to check and then isn't so sure.) Her friend, Lucas, who becomes her accomplice in the plot to rescue No for a better life, is older, and wise enough to know that they might not have the strength to change the world quite as dramatically as Lou hopes.

When No takes up temporary residence with Lou's imperfect family, to Lou's surprise her presence there has a greater effect on Lou and her parents than on No herself. A few nights in a proper bed with home-cooked meals isn't enough to transform her life – Delphine de Vigan deftly resists that particular fairy-tale. But there does remain something unworldly about No and Me, something that keeps it apart from pure, gritty and grim realism. Which is not to say that it side-steps the issues, or pulls back from the truth, or over-simplifies the questions it asks, which it doesn't; rather, the unworldliness comes down to our narrator, Lou.

Originally published in France as an adult novel, No and Me has been chosen for "crossover" treatment by its English publishers, produced simultaneously in adult and teen editions differing only in their cover designs. Indeed, it is easier to see a teen readership connecting with the way the story is told. The perspective is very robustly Lou's throughout (her inability to see inside No's head is significant), and she is allowed – expected – not to understand things completely; to have questions that are not fully answered by the world around her; to feel powerless to control the story as she would like. But adult readers, too, will be charmed by Lou's voice, which is strongly sustained, her intellectual precociousness usefully excusing the fact that she doesn't quite sound like a normal 13-year-old girl.

Well-structured, with moments of tenderness and truth about family and home, inadequate parents and neglected children, No and Me is honest (as revealing and insightful about Lou and home life as it is about No and homelessness) but also at least partially reassuring. Lou's "large-scale experiment against fate" might not go quite according to plan, but De Vigan shows that things really can change, albeit not always in the ways we've anticipated, and not always in ways we can control.