When you are a child, Claire Messud suggests, you never imagine you might not really know the people closest to you. The shock of that realisation, which perhaps comes to us all in early adolescence, is the drama of Messudâ€™s fifth novel, The Burning Girl. The book dwells on the unravelling of a lifelong friendship between two teenage girls in small-town Massachusetts. It is a distinctive and subtle fable of lost innocence told in the voice of one of the girls, Julia, whose middle-class shyness and prized sensitivity prove inadequate as the more disturbed family and life of her wilful friend Cassie violently capsizes.
â€œMy mother assures me that it happens to everyone, sooner or later, for reasons more or less identifiable; everyone loses a best friend at some point,â€ Julia tells herself. But the reassurance isnâ€™t quite up to the reality.
In an office at her publisher, Fleet Books, Messud and I compare notes on how we have experienced something of that reality, first in our own teenage years and then in those of our children. Messud, and her husband, the New Yorker critic James Wood, have a daughter aged 16 and a son, 13. â€œI remember the brutal friendship break-ups from my own youth, and Iâ€™ve watched it again,â€ she says.
â€œThe strangeness is a bit like a relationship with an ex-lover, in that you know everything about your friend, but you suddenly donâ€™t know their daily life any more.â€
That we canâ€™t fathom other people, or ourselves, is the engine of fiction, and Messud, who teaches creative writing at Harvard, has an emotional intelligence steeped in that literary history. She is at once a bold and careful writer, whose previous novels have taken her in unexpected directions and to diverse tones. Most recently they include The Emperorâ€™s Children (2006), a telling dissection of the lives of a group of friends in uptown New York in the years leading to 9/11, and 2013â€™s The Woman Upstairs, a tale of jealousy and betrayal between a frustrated artist and her younger, talented friend.
The books are linked by Messudâ€™s forensic eye for the small currents of tension in human relationships; her first novel was titled When the World Was Steady, but the present of her fictional worlds never quite holds still.
The daughter of a Canadian mother and a French father who worked for a multinational corporation, Messud lived on three continents as a child. The story of The Burning Girl, she says, is rooted in one of the first real-life stories that affected her, and made her want to write. When she was nine she moved from Australia to Canada and kept in touch with her best-friends-forever by sending airmail letters. A girl who had been part of their group went through a disturbing series of events like Cassie in the novel: she grew up not knowing who her father was, and then found out and ran away to meet him, a story that ended in tragedy.
â€œThe thing about it, though, was that I didnâ€™t experience it first-hand,â€ Messud says. â€œI had three or four friends who wrote me their versions of it. It was like the gospels or something.â€ In many ways, she suggests, it was her first experience of unreliable narration. â€œGirls, in particular, use storytelling to establish hierarchies, a pecking order. There is a sort of jockeying of who is in charge of shared history.â€
As a novelist, Messud dramatises that tendency, and points out the cracks in it. She gives the impression of writing being a vocation, a way of finding her voice. Can that be taught, I ask, thinking of her day job at Harvard? â€œNo,â€ she says, â€œbut there are things about writing that can be taught. I would say there are fewer people who want to read seriously now, and more people who want to write. But if you can use writing to get people reading, that is exciting.â€
Teaching also means that her own creative space in the year is quite limited. She laughs. â€œI think there are eight weeks when I am not teaching and the children are in school, which narrows it down a bit, but also concentrates the mind.â€
Does it still feel as necessary as ever to do it, in our world of distractions?
â€œIn the last few years I have come to feel that maybe in 50 years there wonâ€™t be novels, that people wonâ€™t have the attention for it,â€ she says. â€œThen you feel like itâ€™s like a last trace of a culture, like the Lascaux paintings or something. When I am teaching, I first give out Tolstoyâ€™s Childhood, his first published book. It is so transparent. It gives you exactly what it was like to be on a Russian estate in 1830. You are there. And that is the hope when you sit down and write still, I think â€“ that you can transmit something of what life is like now.â€
Her most successful book, The Emperorâ€™s Children, was a big social novel, reflecting New York at the turn of the millennium. Since then she has narrowed her focus. I wonder if the current politics at home are something she would like to address directly in her fiction?
â€œThereâ€™s too much,â€ she says. â€œOne of the things that seems difficult at this point is that the pace of the madness seems so intense. We are all like Linus and Snoopy in front of the TV with our hair blowing back. It is somewhat sapping.â€
For her, though, fiction remains the best means we have of understanding that madness, the ways in which we fail to connect. â€œIf you took my reading and writing out of my head,â€ Messud says, â€œI donâ€™t know who I would be. The people who donâ€™t read, who are they? How do they make sense of things?â€
She references a pivotal passage in her novel, which sounds as good an explanation as any of divisions in our world: â€œAll those years weâ€™d been friends, since forever, weâ€™d used the same words and perhaps meant different things â€“ sometimes slightly different, but other times radically dissimilar; and weâ€™d never known it. As if Iâ€™d been holding an apple and thinking it was a tennis ball, all this time.â€
â€œThat is like the people who donâ€™t read,â€ she says. â€œI donâ€™t know what they mean when they say things.â€
The Burning Girl by Claire Messud is published by Little Brown (Â£16.99) on 7 September. To order a copy for Â£14.44 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over Â£10, online orders only. Phone orders min p&p of Â£1.99