Last week, the owner of Just Dogs pet shop in Stockbridge saw the publication of his debut crime novel, Out in the Cold, which introduces readers to Don Colyear, a police officer with an unnatural intuition.
"I never set out to write crime fiction," admits Johnstone. "I've never read a lot of crime novels, it was too much like a busman's holiday. Actually, with the Stephen King connection, I thought I might be writing something that was closer to horror, but by the time I had finished it looked like a crime novel. By the time it passed by my agent and publisher, it certainly looked a lot like a crime novel, so it's a crime novel but with a supernatural element."
Originally from the tiny village of Dalmally, in the north west Highlands, Johnstone moved to the Capital just over a decade ago, having spent 10 years in the Police force.
"The dog shop first brought me here in 2006," he recalls, adding that after wandering the Capital in search of a suitable location, it was decided Stockbridge would become the home of Just Dogs, which you will find on Deanhaugh Street.
"It was either going to be Morningside or Stockbridge but it became apparent very quickly that Stockbridge was a very vibrant area with a lot of dogs and doggy people.
"A few years after opening the shop, I would come in to work on my days off from the police. I'd get off the train from West Lothian, where I lived at the time, at Haymarket and walk along the Water of Leith to the shop dreaming of the day I could live here. I fell in love with the place. Then, about 10 years ago, I fulfilled that dream and bought a little flat in Stockbridge."
He laughs, "I have the shortest commute of anyone you will ever meet, I live literally metres from the shop and get the strangest of looks when I leave the house with an open cup of tea on my way to work."
Leaving the police force to concentrate on running the doggy specific pet shop, Johnstone also used the career change to do a degree in literature and creative writing in which he has just completed his Masters.
"When I worked in the police I could have an hour commuting there and back. When I left the police I suddenly had those two hours to myself. That’s when I actually picked up the pen again and began to write."
A short time later Stephen King entered his life and suddenly he found his career as an author being fast-tracked.
"I still find it difficult to believe,” he explains. “In 2015 I had been writing short stories for university. A massive fan of the Edinburgh Book Festival I’d been on their mailing list for a long time. That year they ran an advert from the UNESCO City of Literature Trust inviting Edinburgh authors to submit stories for their Story Shop programme. I submitted a short story called The Gospel According to John, which had done well for me at university - UNESCO picked me as one of their emerging writers of 2015."
Through the contacts he made from that, Johnstone learned of a competition being run by Stephen King's UK publishers, Hodder and Stoughton.
"They invited stories based on a quotation from his new book," explains the 43-year-old, "I had another story I was preparing for university that fitted the bill so I sent it in. I forgot about it until I got an email saying I'd been shortlisted for the competition, from 900-odd entries they had whittled it down to six and mine was one of them."
Those six stories were sent to Stephen King to read.
"That was the weirdest week," Johnstone confesses. "I'd been reading Stephen King since I was probably too young to be reading him, it was really strange to know he'd now be reading me. A short time later his representative in the UK forwarded me an email from him telling me the elements he really liked about my story, which was just amazing. She also said he was sending me something in the post. A few days later a copy of his book arrived with a personal message written in it. Then the strangest thing happened, Stephen King decided to publish the six stories as a collection curated by himself."
Fast forward to 2020 and Johnstone is celebrating the publication of Out in the Cold, the first in a two book deal with publishers Allison and Busby.
It opens with a gruesome scene in which probationer PC Don Colyear investigates a sudden death with his partner John - the same John that featured in that short story that saw Stuart recognised by UNESCO - but then, John is based on a real person.
"John was a massive part of my upbringing as a police officer," the writer reveals. "He was in his final two years as a police officer when I was in the first two of mine, my probationary period, when you are expected to learn and show you are capable of doing the job. John was instrumental in doing that for me. A bit like myself he wasn't exactly the biggest of guys so I learned from him the subtle art of tactical communication, using humour to bring a conclusion to what could become potentially dangerous situations. Although I lost touch with him for a long time, his influence stayed with me."
That John really existed, however, posed a problem for Johnstone's publishers.
"When I told them he was a real person, they said, 'Find him and make sure you have his express permission to use his name'. After 15 years I found him on Facebook, met him and had a catch up. I told him about the short story and the novel and he was still the lovely man he always was and very supportive of the book. I think he was pretty flattered."
And Johnstone has good news for lovers of Edinburgh set crime novels. If Don Colyear is the classic fish out of water in Out in the Cold, just wait until the second installment, Into The Dark, when he finds himself transferred once again... this time to North Edinburgh.
Johnstone reveals, "I'm writing the second book at the moment and it is set in Edinburgh. In the first book we discover Don's father comes from Edinburgh so there's a short passage set here. In the second, Don gets to know the city when a particularly grizzly incident brings him here, and here he will remain."
Tomorrow: ‘Fingers burst from the letterbox, tiny fingers...’ Read the first of four extracts from Out in the Cold
Out in the Cold, by Stuart Johnstone, published by Allison and Busby is on sale now, £12.99