It was Stieg Larsson's award-winning Millennium trilogy of crime novels set largely in Stockholm that first sparked Wetzel's interest in Scandinavia. Discovering Larsson's books in 2010, she describes it as “love at first read” and quickly became fascinated by the world she found within them.

“There was something about Scandinavian culture – and in the Millennium books, Swedish culture specifically – that really caught my imagination,” the author explains. “It awoke something in me that made me hungry to learn more about the Nordic countries.”

As soon as she'd finished the Larsson trilogy, Wetzel went searching for more stories in the same style.

“I found that there was a whole world of Nordic noir out there. It was a revelation for me! I went to the library and read voraciously – everything from Jo Nesbø's detective novels to John Ajvide Lindqvist's vampire fiction book, Let the Right One In.”

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For the former journalism student who had previously published her own novels, poetry, and biographies, the books that Wetzel was reading planted the seed of an idea in her head. “I had this fascination with Scandi noir novels and knew almost instantly that I wanted to write my own. But there was just one problem: I'd never been to Scandinavia.”

In the spirit of a research mission, Wetzel booked her first trip to Stockholm, arriving for a three-week-long stay in early 2013. And it was here that the idea for her novel took form.

“I'd heard the story of Olof Palme, the former Swedish prime minister who was assassinated in Stockholm in 1986. As it's a crime that's still unsolved, it raised a lot of questions for me around what could have happened.”

READ ALSO: Olof Palme at 90: 'He matters more than ever'

At the same time, Wetzel was also reading about a fourth Millennium book by Larsson that had reportedly gone missing. “When I came to Sweden from America to write my own Scandi noir novel, these two stories just started to weave together into one book.”

The result was Wetzel's debut book released in Sweden: The Grand Man: A Scandinavian Thriller. It's a detective novel about a journalist who gets drawn into the mysteries of both Palme's assassination and Larsson's lost manuscript, and is set against the backdrop of the Swedish jazz scene.

Wetzel arrived in Sweden in January 2013. And though the Swedish winter can have a reputation for being an unforgiving host – particularly to those unaccustomed to it – for the American it provided the perfect setting for her novel.

“When I thought about my story I thought 'I want to set it in deepest, darkest Swedish winter'. I wanted it to be moody and atmospheric. Coming to Sweden in January gave me that context and the ability to write about it convincingly.”

While the weather may have been cold, Wetzel found that the people she met in Sweden were anything but. “There seems to be an idea of Swedish people as closed and hard to access, but that's not at all what I've experienced,” explains the writer. “Every time I met someone new and told them about the book I was writing, they'd try to set me up with someone who could help.”

It was during one of her stays in Stockholm that Wetzel was put in touch with Gunnar Wall, an author, journalist and Olof Palme expert – who she now describes as “something of a mentor – and a friend”.

“It was invaluable to be able to speak to people like Gunnar. I was aware that I was dealing with Olof Palme's real-life story, so it was essential that I should stay true to the facts of what happened that night. But I do end the book with an imagined solution to both Larsson's missing book and Palme's murder.”

As well as meeting with Wall, Wetzel spent long periods researching and retracing Palme's last walk in Stockholm on the night he was shot. She was aware that her book – currently only available in English – needed to be accessible to both a Swedish and an international audience, so it required a reference to the background of Palme's story in the novel.

“I think one of the challenges was that if you say 'Olof Palme' in Sweden you don't have to explain the story. Outside of Sweden, it's much less known. In the US, for example, only a handful of people really know who Olof Palme was. Lots of people I met in Stockholm found it unusual that an American should be interested in what happened to him. But I really am.”

Florence Wetzel's debut novel in Sweden. Photo: Private

Despite the murky subject matter into which she delves in her books, what most strikes Wetzel about Swedish culture is the importance she finds placed on comfort and a positive ambience.

“Swedish people have a gift for creating atmosphere. I remember walking into a 7-Eleven shop in Stockholm and seeing lit candles. In the US, 7-Elevens are a utilitarian place – you go there to get basic things, but in Sweden there's such an emphasis on creating a mysig [cosy] environment, everywhere. I love that about the culture here.”

Wetzel reveals that it's not Sweden's dark months that have been difficult, but the long summer days. “I find it tricky in June, when birds start singing at 2.30 in the morning and it's totally light at 3am.”

Her suggestion to anyone finding the same challenge is pragmatic: earplugs and an eye mask. Hers, she tells us, laughing, have “served their purpose throughout many a Swedish summer!”

The New Jersey native now lives between the USA and Sweden, spending three months in each country. However, her long-term vision is fixed on her Scandinavian part-time home; she's currently studying Swedish, with a view to applying her skills as an author to the language.

“I'm trying out writing in Swedish, which is great fun. There's a podcast called Creepypodden on Sveriges Radio – they encourage listeners to send in their little scary stories. I've written and submitted one.”

“Ideally I'd love to be able to find a job in Sweden and move here on a permanent basis. That's the dream.”