“Absolutely,” she says. “She’s as hopeless as I was. I was lead trumpet in band as well. I just wasn’t cool.” 

McFall’s early years were spent in England. Although her parents are both from Glasgow, McFall was born in Peterborough, and lived there until her 10th birthday, when the family moved to South Lanarkshire, “a cluster of villages about an hour south of Glasgow”. The community was tight-knit, the area “quite deprived. There are worse places. A lot of the industry like mining has gone”.

McFall suffered her share of culture shock. “I was the English person in the slightly rough Scottish school. Not good.” Like Dylan, she was also shy, cosseted and clever in an environment that didn’t prize any of these traits. “All the girls wore perfume and make-up. Even though they lived in the countryside, they grew up a little faster. I got myself a Scottish accent and learned to swear quite quickly. That was my coping mechanism.”

This jarring experience was softened a little by books: McFall’s formative favourites included boarding-school classic Malory Towers, crime novels by Sue Grafton and Karin Slaughter, and the Point series of horror and romance novels. “I just like being in other worlds and trying on someone else’s life,” McFall says. “You read and get to have a go at being another character for a wee while. If you read books you get to live a thousand lives.” 

It didn’t take her long to try her hand at writing too. “I had a typewriter when I was in school. This, again, is how uncool I was. I used to bash out on blue tracing paper. I would get to 20 or 30 pages and run out of ideas. I didn’t have a concept of what a novel was at that point; the overarching narrative and pacing it takes to create a novel; how little scenes build up into a bigger storyline.”

Ferryman was McFall’s first completed novel. Finished in 2011, the early drafts were “pretty awful. I was very proud of finishing the book, but it was not great, to be honest”. All these early versions had the basic blueprint: bleak landscape, McFall’s teenage heroine and the figure of “Death”, glimpsed everywhere from Greek mythology to Chinese culture. “Quite often he is hooded and you don’t even see his face. I just wanted to give him a more human face. If this was your fate, what would it be like?”

Is she the sort of person who obsesses about death? “You wouldn’t think it to read my books, but I am quite cheery and cheerful. I don’t know what happened!” Nor is McFall religious, a fact that made her uncertain of how to end the story. Ferryman’s original draft left Tristan and Dylan stranded and separated at the gates of heaven. 

“I was nervous of stepping on religion’s toes, but I didn’t want it to be a religious book. How can I write an afterlife that doesn’t tap into any of the religious ideas that we have?” Shining light onto these dark themes is Ferryman’s love story. One glance at the internet comments about both books shows that Dylan and Tristan have ignited readers’ imagi­nations around the world. If McFall isn’t death-obsessed, is she a romantic? 

“I must be,” she responds, a little uncertainly. “I wouldn’t have thought so, but deep, deep down,” McFall giggles. “Everybody loves romance. The whole point of being here is to make connections, and the main connection everyone is looking for is the romantic one.” Ferryman, she argues, is like a primer for serious adult relationships. “When you are a teenager, you are just taking your baby steps into [romance]. When you read fiction, you can practise by experiencing the real emotions of others. It’s like people having crushes on boy bands – it’s safe.” 

Ferryman’s path to success sounds as complicated as Dylan and Tristan’s story. After a bad experience with one literary agent (“a bit of a charlatan”), she found Ben Ellis, who selected Ferryman from a pile of McFall’s completed manu­scripts. “‘It was a sweet little story’ – those were his exact words,” McFall says. “I was quite surprised. It was the first thing I had written and I thought I had got better since then. But he saw potential in it. We call it, The Little Book That Could.” 

The novel was picked up by Templar Publishing and gained further exposure when it was selected by school­children across Scotland for the Scottish Children’s Book Awards. “What I liked about that was it was kids who read it,” she says. “Being an English teacher, there seems to be a divide between literary novels that you can study and the novels kids read for fun. I would quite like to be the novel they read for fun. That’s why I like books.”

McFall was on holiday in America (her husband, Ben, is from Colorado) when she learned that a Chinese publisher wanted to translate Ferryman. An editor at White Horse Times publishing house had read the book and loved it. McFall was sent the finished translation, and “thought that would be that”.

Then, one afternoon in October 2015, McFall was idly googling her name when she chanced upon Dangdang. She was gobsmacked. “Ferryman had got 46,000 reviews. How can it have 46,000 reviews? It was No 10 on Amazon China. I thought, ‘It’s selling quite well.’” 

McFall and her agent investigated. “We discovered the Open Book chart, and Ferryman was in the Top 10. And it stayed in the Top 10 and it stayed in the Top 10. It’s still there. This is the 25th month. It is bananas! I don’t quite understand it. I am delighted.” 

White Horse Times did not contact McFall about Ferryman’s enormous success. She couldn’t read the translation, so couldn’t judge how faithfully it had been executed – “What people have said to me about things they liked has chimed with the story I know” – but McFall educated herself quickly about publishing in China. For one thing, Ferryman was not marketed as young adult fiction, which may explain why some adult readers noted a certain childishness in the prose. “I quite agree with that. When I wrote it, I thought of a teenage audience.”

But the question remains: how did a novel by an obscure Scottish writer about a Scottish teenager and a supernatural being impersonating a Scottish teenager become a block­buster in China? “I am not really sure,” McFall says, smiling. “A lot of things that have come back [from China] are similar to what kids in the UK have said. They really like the love story. They really fall in love with the main character of Tristan. I wrote him as the boy the teenage me would have been intimidated by but would have wanted to get closer to. Me being me and geeky, I would never have dared. I would have run away and hid.” 

McFall also proposes some similarity between her portrait of the ‘Ferryman’ and the heibai wuchang, the “black and white impermanence” deities who, like Charon and Tristan, guide the dead to the afterlife. “But they are quite terrifying. I think readers like the idea of the fantasy journey.” 

Perhaps, I suggest, the trials faced by Dylan and Tristan might chime with classic Chinese myths such as Diyu, the underground maze that dead souls must navigate to atone for their sins? McFall accepts the possibility, but insists that her portrait of teenage angst struck louder, more universal chords with Chinese readers. “Very common questions are: do people in your country have to go to school as long as we have to? Do children in your country have the same kind of life as I have?” 

A lot of readers she met in Beijing asked about the finer points of Scottish culture, like Hogmanay, the New Year’s celebration. Did Scotland need much translation for Chinese fans? “A lot of readers weren’t even aware that I am from Scotland. They just think it’s Britain.” 

Did anyone mention that Dylan is an only child making her way in a tough world, something that might resonate with the one-child policy? “It is very possible. No one has said that to me. But you relate to things in different ways depending on your circumstances.”

To say Ferryman has changed McFall’s life is an under­statement. While she and her archaeologist husband made decent money, they struggled like many others to maintain a certain standard of living. Ferryman’s sales in China allowed them to buy a new house and enabled McFall to teach part-time. “After I had my son that was really impor­tant. I didn’t want to be teaching all the time. Because I write in the evening, when he is asleep, when I am not teaching I can be with him.”

A potentially more challenging consequence of the success is that McFall is no longer writing into a vacuum. The level of anticipation for Trespassers in China was signalled by the fact that the Chinese translation was published almost two weeks before the English original. Did McFall have any hesitation about writing a sequel? She has published two stand-alone novels – Bomb Maker (2014) and Black Cairn Point (2015), the latter having also been tran­slated into Chinese – in between the two Ferryman instalments. 

“I was nervous that people would have had enough of Dylan and Tristan. And also that I didn’t have enough oomph for the story yet. That is why I left it for three or four years. I didn’t want to do it if it was going to be more of the same. That is just stretching something beyond what it should be.”

McFall’s Chinese readership has affected her creative process. One of the souls guided by Susanna, the “Ferry­woman” in Trespassers, is You Yu, an elderly woman who dies contentedly in her village in China. She was, McFall says, named after the grandmother of the rights director at White Horse Times, and was intended as a contrast to the unhappy and desperate souls the writer had depicted before. “A lot of the souls in Ferryman have wasted their lives. I wanted to write about someone whose life was well-lived and who was happy with their time and ready to move on. I wanted someone who was wise and comforting.”

The good news for Ferryman addicts is that McFall has already written 30,000 words of part three. “It doesn’t matter to me that it gets published. I want there to be a completeness to the story in my own head,” she says. Anyone quivering with anxiety at these words might be calmed by McFall’s next. “I imagine it will be published.”

In the meantime, there is another, stand-alone novel to complete, the details of which McFall is keeping close to her chest. And, of course, there’s that movie deal. It seems fitting for this most unassuming of blockbusters that McFall was at work teaching when the news came through. “I was speechless. [Ferryman] started from very humble beginnings. I was delighted to see it in print, then I was even more delighted by its recognition in Scotland. Its success in China has been incredible, and allowed me to share the story with a wide and varied audience, something I couldn’t have comprehended writing those first few words back at the very beginning. 

“Now, with Legendary buying up the film rights, it’s a new chapter. I can’t wait to see what the journey has in store.”