aisy Johnson and I are talking about compost. She never thought she’d write about the Fens, she explains, but she ended up revisiting her childhood landscape in her debut book, a short story collection that won the Edge Hill short story prize. She also didn’t anticipate reworking the Oedipus myth that had so enthralled her in her schooldays, but it formed the bedrock of her first novel, 2017’s Everything Under, which made her the youngest writer, at 27, to be shortlisted for the Booker prize. “Maybe it’s just time,” she ruminates, “and maybe the things I’m reading now will circle back in 10, 20 years … I sometimes think of ideas as a sort of composting and that they just need to compost for long enough, and then you can think about them and write about them.” But the thing with compost, I say prosaically, is that you have to choose what to put in, when to add water and to turn the heap. Johnson likes that idea, and firmly says she’s not the kind of writer that turns away from reading fiction when she’s working on her own books, or steers clear of anything that feels too similar. She is, instead, a magpie, of the belief that “nothing is sacred, and I think we should take everything that we possibly can and make it of our own and send it out into the world”. Her second novel, Sisters, to be published on 13 August, is rooted in her love of the horror genre. As a voracious young reader she discovered Stephen King, along with other favourites Toni Morrison, Peter Høeg and Keri Hulme, and she also cites Shirley Jackson and Helen Oyeyemi as influences on her work. She knew from an early age that she wanted to write; she was, she says, an emotional child, and became entranced by the way that words on a page could make her feel. Sisters is an exceptionally unnerving book, and when I tell her it frightened me she replies that writing it frightened her, too. It’s about two teenage siblings called July and September and their mother, Sheela. The sisters are very close in age, with the older, September, strikingly dominant, but both feel much younger than their actual age, as if their development has somehow been arrested. July narrates the novel, describing how “when one of us speaks we both feel the words moving on our tongues. When one of us eats we both feel the food slipping down our gullets. It would have surprised neither of us to have found, slit open, that we shared organs, that one’s lungs breathed for the both, that a single heart beat a doubling, feverish pulse.” September has demanded that the two of them merge their birthdays, instigates most of their misbehaviour, and sets her sister tests such as running her hand under a hot tap, eating a jar of mayonnaise or cutting herself. We meet the sisters some time after an unspecified disaster that has sent them to a tumbledown seaside house in the North York Moors. Their father is dead – he is a mysterious, often malign absence in the novel, like, says Johnson, a monster in the corner – and the move has precipitated a depression in their mother so severe that she, too, becomes absent, leaving them to forage tinned food and roam about the place while she remains shut up in a bedroom. But it’s the sense of peril that Johnson builds, a kind of suppressed, poltergeist energy, that makes the book propulsive and disturbing far more than any single plot detail. What was she trying to do? It began, she says, as a love letter to the horror genre; but as she wrote it “changed a lot and became about different things. I think a lot of the more obvious horror elements sort of melted away, and what was left was a domestic menace. I think that was what I really wanted, which I suppose is stolen from Shirley Jackson; so that even as you’re making a cup of tea or sitting and watching television, there’s still that sense of tension. And also I suppose with everything I write, and increasingly as I wrote this book, it was about family relationships, not particularly good family relationships, and trauma buried within those relationships and buried within the body.” Where the short story collection Fen alighted on tales of shape-shifting variousness, Everything Under focused on the mother-daughter tie to devastating effect; its “Oedipus” was Gretel, a lexicographer whose mother abandoned their houseboat with an unknown man, and who subsequently spent her childhood in a foster home. Their reunion in Gretel’s adulthood is inflected by their private, invented language and told through the lens of the mother’s dementia. Its originality and linguistic inventiveness drew critical praise – and that Booker shortlisting. “I’m obsessed with mothers,” says Johnson, with a slight laugh – she is also quick to point out that she has a very good relationship with her own mother, and with her sister, and that they are “bemused” to be asked about their relationship with Johnson by her readers. (She adds that when she and her sister were younger, they were “furiously different and probably quite competitive”, and that she was probably more like September and her sister more like July.) Her reading alerted her to the mothers in fiction who existed as “strangely filler characters”, who lacked what Virginia Woolf called the “caves” behind characters – a concept to which Johnson is very drawn. She was also struck by the fact that “as you grow up, people are always asking you when you’re going to have children, do you plan to have children, what are you going to call your first daughter, and that is such a strange thing to grow up with.” The mothers she wants to create, she says, might be struggling to fit themselves into too rigid a categorisation, or might be managing alone – or might even, like Sheela, find themselves frightened of their child: “Motherhood is often portrayed as this very beautiful, very pure thing that every woman is moving towards, and we don’t often talk about the difficulties in it, the particular difficulties when you’re on your own, or when you’re a working mother. I wanted to try to explore that.” Family roles are one facet of Johnson’s fascination with identity, but her books also reveal a preoccupation with physical and emotional fluidity – it’s no coincidence that water features strongly in all of them. Again, the key appears to be childhood: she recalls listening to an audiobook of the Greek myths and being attracted by the idea “that the limits of our body are not necessarily the limits”. When she used Oedipus, she remembers, there was a certain amount of criticism from classicists who felt she hadn’t handled the source material carefully enough; she says the defensiveness interested her, and her excitement about contemporary retellings – in which she includes the work of Pat Barker and Madeline Miller – is based on the way that they allow writers to discuss the present day by “almost tricking the reader”. We begin to talk about the political responsibilities of fiction. Of the recent manifestations of the Black Lives Matter movement, Johnson says: “I think we should feel both as writers and as readers and people that we have to do better”, and while “it’s not an easy time to be looking at yourself or looking at other people, I think that books seem to be at the front of that.” Gender is another matter, and again she cites the Greek myths, and how exciting it was for a 13-year-old to read about Tiresias changing gender, “and it didn’t mean anything, it wasn’t a complicated thing to do, of course you can be different genders, it was just taken for granted”. Fen included a trans character, although “I’m not a trans writer and I think that people should turn to trans writers. But I hope that by writing trans characters I’m doing some kind of good.” At the same time, she’s aware of the problematic nature of many of those ancient myths – particularly in their treatment of violence against women. She recalls reading one in which a gold cloud attacks a woman, but also that the word rape is never used: “That must have really changed the way we thought about our bodies and our boundaries and our sexualities and what it means, what other people can do to your body and what you can do to your own body. “I think it’s high time that we think about those stories, and I guess this is what we’re doing with JK Rowling now. We’re thinking about the stories that our children are reading and what they’re going to teach them.” At 29, she is the right age to have read Harry Potter, and remembers that her family would buy two copies of the books and she and her brother and sister would fight over them. “They were an integral part of my reading experience. You know, it was a really important part of a lot of people’s childhoods.” Does she feel that, if one’s opinion of a writer and their work changes, the value of that first reading can survive? Yes, she thinks so. Her feeling as a writer is that once you send a book into the world, you relinquish it to its readers, and that many Harry Potter fans are demonstrating what it means to be attached to a work of fiction: “That doesn’t mean that we can’t be critical about it and certainly we should be critical about the things we love, and people we love, but we can still remember it fondly and it can still be a very important part of who we are and our culture.” Johnson’s own writing career was transformed by the Booker prize, an experience she describes as “triumphant and wonderful and also so frightening”. She has lived in Oxford – by the river, of course – for eight years, but no longer has to work as a bookseller at Blackwells, or to teach, having the financial stability to write full time, a situation that is “sort of bizarre, but also really wonderful”. Is the fourth book going well? “I’m on maybe my seventh rewrite, but I’m feeling, I don’t know if this will always happen, every book’s hard, but I’m feeling a sort of peace with the process now, which I certainly didn’t feel with Everything Under. I think part of being a writer is finding how you write as opposed to anyone else. And I may be getting there. We’ll see: no one’s read it yet.” Sisters by Daisy Johnson is published by Jonathan Cape (RRP £14.99, 13 August)