Gloomy home office. Let me guess. A novelist? Correct. And not just any old novelist. Karen Thompson Walker has had the worldwide book industry in a frenzy. Such was the ferocity of the bidding war for her debut, The Age of Miracles, it sold for a staggering £500,000 over here and a cool $1m in the US last year.

I thought debut novelists were lucky to get a Snickers bar and a bus fare home from their book launch. What's the book about? The Slowing.

Pardon? Inexplicably, the planet's rotation begins to slow and days gradually lengthen. The phenomenon, known as the Slowing, wreaks havoc: birds drop out of the sky, day becomes night, and governments try to carry on as usual.

No surprises there. Tell me more about KTW. Inspired by the fact that the earth's rotation quickened, by a fraction of a second, after the 2004 tsunami, the Brooklyn-based former book editor spent three years crafting the novel for an hour each morning before work. Yes, yes, you've thought about doing it for years, but she's actually done it. And it's already been optioned as a Hollywood film, naturally.

She says: "Only a couple of colleagues and my husband knew I was working on it – I didn't want to tell anyone in case it was a disaster."

We say: A perfect book for a slow(ing) day.

The Age of Miracles will be published on 21 June by Simon & Schuster (theageofmiracles.com)