‘Every journalist has a novel inside him, which is an excellent place for it,” the American art historian Russell Lynes once observed. Indeed, each week, the in-trays of publishing agents are inundated with scores of novels from newspaper hacks who believe they can make the jump to fiction. But history suggests Lynes was right.

The list of journalists who make the leap successfully – enough, say, to give up the day job – is not long. For every Robert Harris or Sebastian Faulks, there’s a dozen who will fail to make much of an impact. Take Amy Silver, for example. The author of a clutch of a romcom novels with inoffensive titles such as The Reunion, One Minute to Midnight and All I want for Christmas enjoyed a decent following but not one that would have her agent eyeing up a second home in Tuscany.

But what happened when her fourth novel failed to take off has now entered literary legend and given more than ample succour to any journalist wishing to defy Lynes’s maxim.

Paula Hawkins, a former personal finance journalist on the Times and the European, who wrote under the Silver pseudonym, decided to retire the author and strike out under her own name exploring themes that were far darker than those of her first novel, Confessions of a Reluctant Recessionista.

Perhaps she was bored with romcom. Perhaps she was just always that way inclined. “I like bad weather,” she has said. “It suits my mood.”

Short of money, Hawkins fired off 30,000 words, the genesis of a book that became The Girl on the Train, now turned into a film by Steven Spielberg’s DreamWorks studio, starring Emily Blunt. Hawkins’s agent was bowled over by what she had written but the author was not convinced. “She kept saying it was going to be good, but it was one of those things when you’re not sure; it’s like your mum telling you you’re pretty,” Hawkins told the Guardian.

That interview was in April, only 16 months after the book first hit the shelves. Since then, TGOTT has sold, according to a Forbes estimate in August, more than 15m copies, catapulting Hawkins into last year’s top 10 highest-earning authors.

Transworld, the publisher, had initially ordered a print run of 12,000 copies in the UK. Certainly, the book’s outline would have given little clue as to its potential – the tale of a lonely alcoholic, Rachel, who has lost her job, but who, for the sake of appearances, continues her daily train commute. Few would have predicted it would go on to become Amazon’s bestselling book of 2015.

It is tempting, for the sake of an easy narrative, to suggest that Hawkins’s success was achieved almost accidentally. She was clearly taken aback by the sheer scale of the book’s success. “You can tell when there’s going to be a good response, but you can never really tell when something is going to become so huge,” she told the Evening Standard. “There’s an alchemy to it that I don’t quite understand.”

Transworld launched a campaign around the book at the Harrogate Crime Writing Festival in July 2014, six months before publication, with proof copies targeted at key figures in the book world. Riverhead, the US publisher, was similarly shrewd in its marketing. The Amazon-owned Goodreads website notes how some 4,000 advance reader copies were sent out to booksellers, readers and critics to build a buzz around the title long before it hit the shelves.

Such initiatives are not unusual although the scale of the distribution – and its targeting – was much more sophisticated than most campaigns. One person who received the book was Stephen King who tweeted that it had “kept [him] up most of the night. The alcoholic narrator is dead perfect.”

As word travelled, the buzz became a roar on social media – Reese Witherspoon posted an Instagram of herself reading the book – and pre-orders from booksellers started piling in.

Published in January, a quiet month when publishing houses blood new authors before established writers bring out their summer or autumn novels, TGOTT benefited from some early favourable reviews.

Hawkins, for years the one asking the questions, suddenly found herself on the receiving end of interviews and the subject of huge media attention, something that made her feel uncomfortable. “I’d been worrying for so long about my financial situation, what I was doing with my life, so I felt relief, then fear, with the realisation that when something starts to do very well, lots of people are going to read it and that makes you feel really quite vulnerable,” she explained.

It helped that Hawkins had written a book that was bang on trend. Rachel’s unreliable narrator drew comparisons with Gillian Flynn’s blockbuster Gone Girl that had come out a couple of years before and demonstrated that there was a huge demand for dark psychological thrillers with strong, complex female characters.

Hawkins, who was born in Zimbabwe but grew up in the UK and studied politics, philosophy and economics at Keble College, Oxford, acknowledges why people bracket her with Flynn. “There’s something about that highly flawed, messed-up female protagonist that people seem to like at the moment,” she said.

But in interviews she also gives the impression that she feels the comparisons are sometimes overdone. True, both have a missing woman at their heart and paint in claustrophobic detail portraits of disintegrating marriages. But whereas Flynn’s character, Amy Dunne, is menacing, powerful, manipulative, Rachel Watson is almost the opposite. A woman with a faltering, gin-soaked memory, she is trying to do the right thing. She is pitiable and vulnerable. At one stage, in a line that has provoked much attention, Rachel acknowledges: “Women are still only valued for two things – their looks and their role as mothers. I’m not beautiful and I can’t have kids, so what does that make me? Worthless.”

Rachel is also conventionally, aspirationally suburban, a peculiarly British type of character perhaps. Whereas Amy has a psychopathic hatred for small-town Missouri to which she has been forced to decamp from a vibrant, intoxicating New York, Rachel has a fascination with those whose homes she passes on her daily commute. It is a fascination that many British commuters will recognise, not least Hawkins herself.

“I commuted into the centre of London every day, and I used to sit on the train,” Hawkins, 44, told Time. “For parts of the journey, I would go quite close to people’s homes and I always liked that – being able to see inside people’s houses and imagining what those people were like. And then I was sort of idly wondering what one would do if one saw something shocking.”

Playing around with a character’s perspective is as old as the thriller itself, in book or film. One of its most celebrated exponents is Alfred Hitchcock and it is no surprise that Hawkins cites him as an influence. “I was going for a slightly Hitchcock-style atmosphere,” she told Time. “I did want that feeling of paranoia, self-doubt, suspicion.” Perhaps this explains the book’s appeal. In Rachel we see a woman out of control. But we also see ourselves.

Some feminist critics took issue with how Hawkins (and Flynn) depicted the abuse of women. And some readers carped that they saw the twist coming from far off. But many echoed Stephen King who tweeted, TGOTT is a “really great suspense novel”. Whether the book’s millions of readers will warm to its depiction on the big screen remains to be seen. A pulchritudinous Blunt will make for an interesting Rachel. The twitching curtains of suburban London have been replaced by the river towns of upstate New York. There is, apparently, a lot more sex.

Hawkins has had no creative control over the film, which is probably just as well as she has needed the time to polish her follow-up novel about which little is known other than it may be “gothic-tinged” and about sisters. Inevitably, expectation is huge. Transworld is allowing impatient readers the chance to sign up online to receive the first chapter. It’s yet another confirmation of just how far Hawkins has come in such a short space of time.

Born Paula Hawkins, 28 August 1972, in Rhodesia (now Zimbabwe), before the family moved to the UK. Studied politics, philosophy and economics at Oxford, and worked as a personal finance journalist for the Times.

Best of times This August, she entered the Forbes top 10 highest-earning authors on the strength of the first novel written under her own name, The Girl on the Train.

Worst of times A run of romantic comedy novels, written under the pseudonym Amy Silver, failed to catch fire.

What they say “Hawkins juggles perspectives and time scales with great skill, and considerable suspense builds up along with empathy for an unusual central character who does not immediately grab the reader.” The Guardian

“Hawkins’s first thriller is well-written and ingeniously constructed – perhaps a bit too ingeniously… But the portrait of Rachel as a chronic drunk who might just save herself by playing detective is memorable.”

The Washington Post

What she says “I think people have got a little bit tired of a trope of a beautiful dead woman on the first page of a novel. It’s more the psychology of crime going on. They don’t tend to be so much about violence or about bloody acts.”

• This article was amended on 4 October 2016 to make it clear that Transworld is the UK publisher of The Girl on the Train. Riverhead is its US publisher. It has sold 15m copies worldwide so far, not, as we said, 11m.