Liz Jensen is in the middle of moving home, from her Wimbledon house of 12 years to Copenhagen. She has warned me that the house is stripped bare so that its interiors look "straight out of a Scandi-crime set." It would be fitting for a novelist who is not only half-Danish but has won acclaim for the kind of eloquent and pacey psychological thrillers that a Scandi-crime screenwriter would die for to be ensconced in a terrace house which looks like it has just been vacated by forensics.
In reality, Jensen's house turns out to be warm and welcoming. So too does Jensen – tanned, elegant, good-humoured – for a writer whose imagination has ranged into the mind's darker nooks and crannies. In her fiction, life as we know it could soon be wiped out (The Rapture ended with a climate catastrophe), and even utopias turn quickly dystopian (The Paper Eater features the "perfect" man-made island of Atlantica).
Most of the household bustle takes place in Jensen's kitchen. She points to the bare bookshelves and cracks a joke about being won over by her e-reader; her son, Raph, yawns awake over a bowl of cereal (he's just finished his A-Levels). Her husband, the Danish writer Carsten Jensen, makes coffee topped with the kind of froth that only good pavement cafes whip up. In the middle of it all, there are two laptops on either end of the kitchen table that mark where the Jensens write, face-to-face, as family life rumbles on around them.
Here she sat to write (in part) her latest, eighth novel, The Uninvited (Bloomsbury, £12.99), a hugely inventive generic hybrid, part-crime thriller, part-morality tale, that dances along the borders of SF as a fast-spreading epidemic sees children killing their parents. As is often the case in Jensen's fiction, two worlds gallop alongside each other, both our recognisable universe in which her handsome, hyper-rational protagonist, Hesketh Lock, investigates corporate sabotage, and a far less familiar territory, a nightmarish "other" world in which children seem to be suffering the contemporary equivalent of demonic possession. The seeds of this other world do not lie in futurism or SF, Jensen says. The Uninvited is her endeavour to write a 21st-century ghost story in which the terror is on an epidemic scale. "I started with the idea of a haunting. I re-read books like The Turn of the Screw, The Woman in Black, and the stories of Edgar Allan Poe. I wanted to do the opposite of what these stories were doing, to write a post-Freudian ghost story.
"The haunted house in these books often represents the family and the mind, and the haunting is related to the conscience. But the haunted house here is the planet. "
The story's creepiness cranks up incrementally, with moments of eerie revelation that don't break out into full-blown horror (or at least, not until the end) but teeter on a far greater point of tension. The idea of child possession, of innocents turned evil, is its most unsettling element, along with the conceptual blurring of evil and good this brings. "I don't like the world 'evil'," says Jensen. "I'm not at home with it. This is about perspectives. Something seen from one perspective seems like a good thing but seen from another perspective, is murderous."
Jensen's oeuvre has shown surprising generic diversity; her readers never get a repeating tone or subject-matter. Even within a novel, there is a generic mash-up. The diversity is partly for her own benefit – "I don't like to feel like I'm covering the same ground twice". Yet this latest book takes care of "unfinished business" that began with The Rapture, whose plot revolved around a teenager who has murdered her mother and has premonitions of an earth-shattering catastrophe.
Jensen moved onto something completely different after finishing it in 2009, but certain themes returned and demanded unravelling. Eighteen months later, she put aside the book she had been working on and The Uninvited came into being.
One of the most striking aspects in Jensen's work is the quasi-religious symbolism – the apocalypse, demonic possession, the flood – that is re-appropriated to take on a secular significance. What she is interrogating is not the Christian belief system, she says, but a contemporary belief system for living – how we survive in the world, especially amid climate changes, who is causing the destruction and "the levels of denial we indulge in to pretend it is not happening."
"I continue to read about the climate. To me it's the biggest moral issue of our time. The question for me is 'how can I write about it in new ways?'"
The Uninvited, she says, is a high-wire act. Some people might not buy its vast imaginative what-ifs. But it is these lavishly imagined lives and worlds that she applauds most as a reader herself. "The writers I most admire are the ones with the biggest imaginations, and writing that uses the world of now as a starting-point but makes it into something that is much bigger and wilder. I like the story that will break across into a new frontier, that will go into a wilderness."
Her own starting-points are grounded in the factual: newspaper reports, research gleaned from the pages of New Scientist and books on climate (Professor Callum Roberts's Ocean of Life sits on the mantelpiece). "It's fantastic," she says, pointing. "How could you not come away with your head bursting with ideas?"
Filmmakers have loved her high-wire act with all its imaginative gymnastics, and the pace and visual appeal of her plots seem particularly attuned to the screen. The Rapture was optioned (by Warner Bros), as was My Dirty Little Book of Stolen Time, while War Crimes for the Home was adapted for stage in 2003. Most famously, The Ninth Life of Louis Drax, her stunning fifth novel which combined a family mystery with the inner voice of a boy in a coma, was the subject of a vigorous studio battle. Miramax won and Jensen received a princely sum which afforded her valuable time and space to write what she really wanted to, and tear up the stuff that didn't quite work (Carsten Jensen says "she has a high throw-out rate"). The film was to be directed by Anthony Minghella, but was grounded when he died.
The easy conversion from book to screen might be down to a former career as a radio producer, where dialogue and word-pictures are paramount, though the visual imagination came later, she says.Her first job was at the South China Morning Post, which she landed during a year out from Oxford University. "I was restless and I didn't particularly enjoy my first year at Oxford."
She came back to finish her degree but took off to Taiwan straight after to work on a radio station and carried on in TV and radio production at the BBC in London. In the 1980s, her former husband, a medical researcher, got a job in France and she finally decided that now was the time to write fiction."I always tell my creative writing students not to give up the day job, but I had to give up the day job to write." Curiously, the pram in the hallway helped. The birth of her first son, 23 years ago, was a trigger. "I was incredibly productive. I wrote Ark Baby in the two hours a day when he was asleep."
Alongside the dystopian dreams in Jensen's world, there are happy endings ("You have to end with a note of hope, otherwise it's bad manners") and some burning romances too. In The Rapture, the wheelchair-bound psychologist, Gabrielle Fox, has a passionate love interest. In The Uninvited, the love story is between Hesketh and his stepson, Freddy.
There is a history of ardent and unexpected romances in Jensen's own background. Her Moroccan, Oxford-educated mother met her Danish father, a carpenter who left school at 14, on a backpackers' holiday. Then there is Jensen's own romance with Carsten Jensen, begun inauspiciously more than 12 years ago. "We first met in 2000 at a literary festival in Ottawa. There were a lot of Scandinavians there. I suppose at the start I slightly resented that there was another Jensen at the festival. No writer wants to share their name with another writer. It's really not cool."
A friendship evolved, and then became more. Now they are mutual admirers ("He really is very knowledgeable"; "Liz is extremely generous"; "I shamelessly nick his ideas"; "I regard Liz as my real editor"). They married two years ago, and it seems like the perfect romantic ending for Jensen – and Jensen – sitting at opposite ends of the kitchen table, happily imagining alternative worlds.