GAIL Honeyman shakes her head, as if to shrug off the shades of a dazzling but unbelievable dream.

We are meeting in a cafe bar in the west end of Glasgow, where her debut novel, the source of that sense of slight but delighted bewilderment, is also largely set. Her book is entitled Eleanor Oliphant is Completely Fine. It is a moving, funny, and by the end, devastating novel, and also a rare thing: a debut novel from Scotland which pitched the literary world into a kind of delirium. Ms Honeyman, 45, wrote the novel while she worked at Glasgow University - she created it, as many aspiring writers do, in snatched parcels of precious time - in the morning, in the evening, on holiday. But when it was complete, and in the hands of her agent, it ignited the publishing world. "It was a massive shock," she says.

On the eve of the 2015 Frankfurt Book Fair, the novel was at the centre of a bidding storm for its rights. Eventually Harper Collins bought it, and the rights to a second book, for a 'high six-figure sum' after a "fierce eight-way auction", it was reported. The rights have subsequently been sold to 28 publishers around the world, including a major US deal. And last week it was announced that the Hollywood actress Reese Witherspoon's production company Hello Sunshine had bought the rights to take Eleanor to the big screen, with Witherspoon, it is believed, lined up to play the title character (whether Ms Witherspoon will play the role in a modern Glasgow setting is not yet known.) Ms Witherspoon has yet to call the author, although one suspects that may happen soon. For such a frenzied commercial fight over its rights, one might expect Ms Honeyman's book to be a very commercial, mainstream affair. But, intriguingly, it is not quite that. It is approachable and highly readable, but if its prose is nimble and clear, it is fleet and sure over some shiveringly dark fissures. The story slowly reveals its secrets, and all is not what it seems.

But the central character and life of Eleanor - socially awkward, extremely lonely, isolated, and physically and mentally scarred - is the heart of the book. Eleanor is an isolated, spiky character. She has no friends. She always wears a jerkin. She leaves her dull office work on a Friday and returns on Monday morning, have usually not spoken to a soul - her pot plant does not count - over a weekend. She uses vodka as a sedative, and lives as if on a frosty, tightly constructed pane of ice above an unexplained chasm of pain. Her internal voice, beautifully created by Honeyman, is pedantic, naive, funny, cutting, and seemingly logical, albeit marbled with ingrained agony. One half of her body is covered with severe scars. She is a remarkable creation. When a shambling but patient and tolerant man, Raymond, enters her life, his kindness ripples through the as yet unplumbed depths of her past and future. By the end of the book those small doses of love and kindness have both revealed the source of Eleanor's pain and also set the character on a path to comparative normality.

Set, albeit with a light touch, in Glasgow, it is also funny. One can see why publishers leapt at it: the anomie of urban life is captured here, the details of dismal Meal Deals, anaesthetising home measures, Eleanor's resistance to the endless landfill of popular culture, makes it a novel also for our harried, compressed, lonely urban times.

Honeyman still finds the tidal wave of success, for a book barely published, is a little hard to take in and accept. "I thought it was very specifically Glaswegian story and certainly Scottish story, so when it sold in Korea and Japan...I suppose the city setting does translate to other countries," she notes. We drink tea, Glasgow noisily rumbles outside, and she adds: "Still, talking to you now, it doesn't feel real: but because it is all so hard - it is so difficult to get an agent, to get a publisher, to write and finish a book. I was always managing my expectations very rigorously."

One day, after her novel attracted an agent, Madeleine Milburn, her mobile phone buzzed. She adds: "I couldn't believe it, and still cannot believe it. I had no expectations whatsoever, because I had to manage them. The fact that there had been an auction in the UK, and then in the US, and then in Germany: I had never in my wildest dreams expected to have that. I was just going to work, and I checked my phone and there was an email about the auction and I wasn't sure how to deal with it. Never in my wildest daydream did I expect that."

Mainly, the financial success meant she could give up her job, and write full time. So how did she begin this journey? She grew up in 'central Scotland' and studied French language and literature at the University of Glasgow. She went on to study for a PhD at Oxford University, in 19th century French poetry - but as much as she loved the subject (and still does) she realised academia wasn't her calling. After some time working in the civil service, and economic development, she worked in the post graduate administration at Glasgow University. And she began to write the strange but compelling tale of Eleanor Oliphant. "After it was sold, I left my job three months later. So I have been writing full time for over a year now, which is another dream," she says. "My boss knew that I was writing, so was always supportive. They were lovely about it: it wasn't a big dramatic scene. I didn't hate my job." But she had come a long way in a short period of time - she only decided to write the novel five years ago. She says: "It was just before my fortieth birthday. A big birthday like that focusses your mind. It's 'either I give this a go, or I put it in the bin. Because it is annoying me, niggling away.' It is a strange and wonderful thing now to be talking to people about my book."

Eleanor came to Honeyman after a rumination on a number of issues. Honeyman says: "She sort of appeared to me. I had been thinking about social awkwardness, and about people you meet who are not bad people, there is nothing wrong with them, but they are just a little bit awkward and it makes you feel uncomfortable and it makes you want to bring the encounter to an end. I thought: is there a reason for that? What has contributed to their demeanour?" She adds: "And I was thinking about loneliness as well, I read an article about life in the late 20s - the usual portrayal in sit-coms and films is that life is one big party- but actually life can be challenging at that age. Once I thought about how someone could find themselves in [Eleanor's] situation, it wasn't hard at all to think of why. I understood how she became the way she is."

Novel writing isn't autobiography, she adds. Eleanor is not Gail Honeyman (although I suspect they share a sense of sharp humour). "There is nothing of me in Eleanor, thank goodness. She is in a bubble, a glass case. And often people talk at the water cooler, or with neighbours and friends, but she doesn't even have those, so she is isolated in the greatest ways and in the most trivial ways too."

Raymond, in his tousled way, is the gentle but persistent catalyst for change in her life - but not necessarily romantically. She nods and says: "I wanted to show platonic friendship between men and women, because I think it is underutilised in fiction. Raymond is a sweetheart. They see each others flaws very clearly, and they are not dazzled by romantic attraction."

Indeed the characters in the book are more bound by friendship and decency than by grand passions. It renders Eleanor's story more fragile, and believable. Honeyman says: "I wanted to write about the transformative power of small acts of kindness. An old man falls in the street, you stop and make sure he's OK. Or even smaller acts than that, though - buying someone a cup of coffee, telling them their hair looks nice, sometimes you don't realise the transformative effect on people. I wanted to celebrate that." She adds: "Life is hard sometimes, and those little things help get you through."