From this height the sleeping city seems like a child's construction, a model which has refused to be constrained by imagination. The volcanic plug might be black Plasticine, the castle balanced solidly atop it a skewed rendition of crenellated building bricks. The orange street lamps are crumpled toffee-wrappers glued to lollipop sticks.

The most difficult part of any crime novel is the plotting. It all begins simply enough, but soon you're dealing with a multitude of linked characters, strands, themes and red herrings - and you need to try to control these unruly elements and weave them into a pattern.

I don't think I have one particular favourite writer. I have many whose works I will always buy or reread - Muriel Spark, Anthony Powell, Robert Louis Stevenson, Ruth Rendell, James Ellroy, William McIlvanney, Kate Atkinson, John Burnside, Louise Welsh, Iain Banks.

At all times, think like a writer, and keep those antennae twitching - that way, you pick up new ideas.

I started writing novels while an undergraduate student, in an attempt to make sense of the city of Edinburgh, using a detective as my protagonist. Each book hopefully adds another piece to the jigsaw that is modern Scotland, asking questions about the nation's politics, economy, psyche and history ... and perhaps pointing towards its possible future.

I don't have many friends. It's not because I'm a misanthrope. It's because I'm reserved. I'm self-contained. I get all my adventures in my head when I'm writing my books.

I've always written. At the age of six or seven, I would get sheets of A4 paper and fold them in half, cut the edges to make a little eight-page booklet, break it up into squares and put in little stick men with little speech bubbles, and I'd have a spy story, a space story and a football story.