When American bookshop employee Hugh Howey wrote a short story called Wool two years ago, he could never have predicted it would become a publishing phenomenon that is being lined up for a Hollywood movie.
Howey's dystopian tale sees humanity confined to a gigantic subterranean silo split into 150 levels. The only view of the outside world is via a screen that transmits an image of a ruined landscape.
The ultimate punishment is "cleaning" - in which the condemned individual is sent out to polish the camera lens. The poisonous atmosphere on the surface means certain death.
When Juliette, an engineer from the lower levels, becomes Sheriff she makes a discovery that makes her rethink the world as she knows it.
Howey self-published his short story as an ebook in July 2011 - priced at under $1. He had already self-published several novels, but Wool gained a momentum of its own.
Howey expanded the story into a five-part novel, got a publisher, quit his job, and sold the film rights to 20th Century Fox with Sir Ridley Scott, whose films include Alien, Bladerunner and Prometheus, as a partner on the project.
With two more Wool-related novels - Shift and Dust - due out later this year, Howey explains his extraordinary journey from bookseller to best-selling writer.
When did you get the idea for Wool?
It goes back six or so years. I left a yacht captain job which had taken me to places like Barbados, Cuba and Nicaragua and followed my wife inland so she could study for her doctorate. I noticed my window on the world shrink down to a TV screen. I remember that being the genesis of the wall screen in the silo.
How did you arrive at the unusual title?
I started thinking about how they would do the "cleaning" and I came up with the wool scrub pad - and then it occurred to me that the wall screen was pulling the wool over your eyes. I thought it was a short story that no-one was going to read, so it was okay to have a quirky title.
Why did the short story turn into a full novel?
It went up in July 2011 and I went back to writing a novel in a series I was working on. Three months later I noticed that sales for Wool were outpacing anything I'd done before.
I remember being up at midnight on 31 October hitting refresh, and waking my wife up to tell her it had over 1,000 sales in a month. The next morning I started writing Wool 2 and it kept snowballing.
How involved were your readers in shaping Wool?
I liken it to the difference between recording an album in a studio and playing live. When you play live it's you and an audience and you get energy from the applause.
Everyday I was getting emails, Facebook posts and tweets. It was energising knowing I was writing for an audience.
I've hidden my phone number in one of the books and people find it and call me randomly. It's awkward when it happens but I like that blatant transparency about everything. This ride's not going to last forever and why not just enjoy it?
What's it like dealing with publicists and agents?
Agents started calling me when the first four Wool books were topping the the science fiction chart on Amazon.
The agent I'm with now hired a co-agent in Hollywood to take it to JJ Abrams and Joss Whedon and all those guys - and Ridley Scott's the one who won the rights for it.
How likely is it the film will get made?
I've had really low expectations because I've worked in the book industry and I've seen how many books get optioned - but everyone is really excited about this.
Me and Ridley Scott have exchanged emails, but he's the top of the food chain and would get involved when this thing goes ahead.
Have Ridley Scott's films been an influence?
I'm sure I was influenced growing up on Alien and I'm sure Ripley [the character played by Sigourney Weaver] was in my mind when I wrote the character of Juliette. I'm sure the pacing of Wool also harkens back to his older works where you can develop characters and tell the story rather than starting off with explosions.
Did your many years living on a boat influence Wool?
What did seep through was the class structure [that manifests itself in the different levels of the Silo]. I worked for billionaires on boats with hot tubs, but I was down in the bilge - covered in grease - taking a pump apart.
I got an appreciation for stratification - the higher up in the boat you are the nicer things are. I felt like a combination of Juliette and Han Solo - I was always banging something with a wrench.
Why is dystopian fiction so popular?
Because we're a terrified people - we feel like our survival is tenuous and depends on other things that could be stripped away from us at any time.
Science fiction is usually on its own bookshelf - do you see it going mainstream?
It's there with the fantasy books - they throw dragons and spaceships together. It does go mainstream, but then it's not called science fiction. This happened at the bookstore where I worked. If a science fiction book - like Frankenstein - was considered great we took it out of the science fiction section and put it in literature.
How do you see the relationship between the physical book and ebook?
I've grown up worshipping books my whole life. What I had to learn with the rise of epublishing was that I was confusing my love of books for my love of story.
An ereader will give you the story without the book. Now I love the story no matter how I get it.
I think people will buy multiple copies if we price them correctly. I think hardbacks should come with a free ebook - and then you have the convenience and the collectable. It's still so new, everyone's making it up as they go.
Wool is published by Century in hardback, and Shift is published in hardback and as an ebook on 25 April.