Drawing out the dispossessed: Jon McGregor tests his readers' loyalties with his latest novel

Jon McGregor's latest novel, Even the Dogs, following a group of homeless drug addicts, is a radical departure from his previous work.

'The air is cold and vice-like," Jon McGregor's third novel begins; "the sky a scouring steel-eyed blue, the trees bleached bone-white in the frosted light of the sun." This typically striking McGregor phrase – elegantly pared down, a poetic distillation of hard surfaces – amply captures the bracing day when we meet upstairs in the Nottingham Writers' Studio, a collective meeting house and workspace for professional writers that McGregor founded in 2006.

Two years ago the Studio relocated from a freezing garret to its current eminence where we sit looking out over the reposed calm of St Mary's, whose beautiful churchyard is bounded by gentrified townhouses, boutique hotels and lawyers' offices, in Nottingham's historic Lace Market quarter. This affluent, orderly world masks another. Whilst researching the locations, argot and paraphernalia of the novel, which follows a group of homeless addicts for the few late December days surrounding the death of one of their number, McGregor had lunch outside a nearby café with someone who had been a very heavy heroin user living on the streets. "Just round the corner there, in an alleyway there, down by where the heat pipes are," McGregor gesticulates, "he was naming all these places within a hundred yards of where we're sitting where people regularly slept rough." When a couple of men walked quickly past, McGregor's interviewee had interpreted: they've just got enough money to score. You can tell by the speed they're walking. That backpack will have his water bottle, needle and the rest of it in. "I had a real insight," McGregor admits, "into how this drug culture is all around us, but it's very easy to miss – and very easy to ignore."

Even the Dogs (Bloomsbury, £16.99) began life in 2003 when McGregor heard a story about a man being found dead in his flat in vaguely similar circumstances to those of Robert, the alcoholic whose wrecked apartment has become a drug-taking sanctuary for the novel's rag-tag gang of users. After writing the first chapter, he realised that if it was going to become a novel, "then it was going to be a novel about drugs and homelessness and alcoholism, and I didn't really think I wanted to do that sort of book; so I put it away for quite a long time". It continued to ferment. His initial decision to use ghosts as partial narrators first appalled and then re-intrigued him, as did the difficulties of writing with a degree of authenticity (given his own distance from "that kind of life") and of avoiding the easy pitfalls of cliché. The result, McGregor admits, is "pretty dark". A week after his death, Robert's putrescent corpse is discovered by Danny whose paranoid, jittery, smack-craving trajectory away from this ghastly scene, trailed by his blanket and Einstein (the three-and-a-half legged pooch with whom he has the novel's most rewarding relationship) forms the narrative impetus of this charged, challenging work. In a geographically unspecific landscape of flyovers, towpaths and urban dereliction, Danny's path intersects with the dysfunctional lives of other addicts whose fractured stories gradually cohere into a lucid, distressing vision of a sub-culture that has no meaningful interaction with functional, workaday life.

"I took advantage of the metaphor of the ghosts," McGregor explains, "to reinforce the sense of it as a parallel reality – that these people are living in a ghost world that shadows the rest of us." The mechanistic, locked routine of addiction (wake up, get money, get drugs, take drugs, get more money, take more drugs, find sleeping pitch) allows for no emotional maturation, McGregor points out, which leaves users in a limbo-like mill of dependency. The ghosts quietly peer in and comment on this frantic existence as though providing the chorus to a Greek tragedy – although this is the extent of the comparison; readers looking for any glimmer of heroism, a tragic flaw, a sense of catharsis or any significant redemption will be heavily taxed.

Gradually, McGregor found that his ghostly apparatus allowed the book to be read on different levels according to the reader's preference, from dream or vision to TV script. Readers familiar with his ruminative 2002 debut If Nobody Speaks of Remarkable Things will recognise a fondness for the carefully ordered snippets from individual voices building into bigger, impressionistic canvases. The first book's nuanced meditation yields to jagged, fractured yelps in Even the Dogs, reflecting the anguished, desperate states of its characters, with the ghosts acting as ethereal continuity links.

Whilst this new novel draws on the stylised structure of his highly praised, strong-selling debut, and suggests some of the curatorial ambience of So Many Ways to Begin, a second, introspective novel that subtly probed significant gaps in a family's heritage, Even the Dogs is a bold departure for McGregor. "It felt like a very significant move away from the first two." Once he began writing in earnest, he quickly realised that the book was going to be "very dark, fairly unpleasant to read, full of swearing and unpleasant images; it's going to be a completely non-realistic narrative perspective, and it's going to be fragmented and non-linear but within a strict structure. There's going to be a whole bunch of people who don't like it; and quite a lot of them are going to be those people who did like my first book. And they're going to dislike this for the reasons that they did like the first one."

An economic downturn seems a tough period in which to launch a difficult, serious and highly literary novel on a potentially unattractive subject, but thirty-four year-old McGregor remains bullish (if that epithet could ever be used of his slim build, salt and pepper hair, small glasses and the modest delivery of his pensive, unhurried answers). On the back of sales from his first two Booker Prize nominated novels (which also scooped the prestigious Betty Trask and Somerset Maugham purses), he's avoided "a proper day's work" for eight years, he jokes – but with regard to his latest work, he points out how the likes of David Peace have found commercial success for intensely written, formally challenging works. As well as their passing similarity to Peace's disjointed episodes, the five sections of McGregor's work are each underpinned by modulating themes that are strongly reminiscent of the shifting motifs in David Mitchell's number9dream. Neither writer was an explicit influence. He claims John McGahern, Alice Munro and Richard Brautigan (who all effortlessly mix the highbrow with the accessible) as writers he admires, but when I suggest that Even the Dogs reminded me of WG Sebald's hallucinatory prose and evocative sense of mental space, McGregor cocks an eyebrow.

"I've been reading him voraciously in the past few years but assumed there'd be no seepage," he admits simply. "One of the things that impresses me about his writing style is that he does something unusual and clever and difficult just in the way he integrates the different levels at which he's writing." He cites The Rings of Saturn as a potent example, an ambulatory, philosophical work in which Sebald walks around a landscape already familiar to McGregor from his East Anglian childhood, drawing significance out of "a ragbag of interesting quotations and citations" that he manages to integrate into a long sentence: him walking along the beach, his personal analysis of the thing he's reflecting on, a scene from a painting, the time when he was in the gallery looking at the painting, the friend that he met in the gallery and that friend's history.... "It's very seamless and feels visionary. He's using the possibilities of written prose to have a great big cinemascope perspective which – it occurs to me now, and only now – is what really interested me about the possibilities of the perspective that I chose for Even the Dogs. Even though the first chapter is basically flashbacks, I tried to write them without the appearance of flashbacks because they're narrated by ghosts that can see back through time. It's all quite simultaneous."

So what, from the swearing and self-harm, the ethereal chorus and atomised misery, does the author hope the reader might take away? We pause. McGregor expresses a wariness of writers who "get into the habit" of standing on platforms – as though this in itself is a dangerous addiction. While writing, he was conscious of not letting himself slip into messages or campaign issues, sticking instead to an authorial commitment to making the lives of his fiercely vivid characters as true as possible; and to making it "if not entertaining in the obvious holiday sense, certainly engaging, engrossing". He's achieved this much, without doubt. Substantial research into the many intervention agencies supporting his characters' chaotic lifestyles has paid dividends in giving parts of the novel the taut grip of a forensic procedural. There are glimmers of humour, too; but the overall tone remains undeniably bleak.

"My main objective is simply that people come to know these characters, understand and feel some sort of empathy with them and care about where they're going," McGregor concedes. Where they are going, however, with one fragile exception, is back out onto the street in search of drugs, or sliding relentlessly towards an early death. The one fragile exception does give dynamic leverage to a book that conducts a courageous scrutiny of violent, degraded, treacherous, vulnerable lives, challenging the reader to look again. And, despite his stated unease with issue-based fiction, McGregor seems to want to raise his readers' baseline engagement with the world, at least in terms of awareness. "It would be nice," he concedes, "if somebody read this book and could then spot the person walking particularly quickly with the backpack, on their way to buy drugs. And open up to see the ghost world."