In reply to Tall Clare:
Since you mention Alan Warner - how about These Demented Lands & The Man Who Walks?
Several of Christopher Brookmyre's novels rely on their rural setting, off the top of my head: One Fine Day in the Middle of the Night, A Big Boy did it and Ran Away & Pandaemonium, but there are others...
Serpentine by Tom Morton is a wonderfully, sarcastically, entertaining thriller.
I've just finished Site Works by Robert Davidson which I thought was brilliant & I don't think it was just because of the subject...
Anne Cleeves Shetland Quartet are tightly written crime novels & Peter May's Lewis Trilogy are shaping up to be much more than that if the 2nd & 3rd books are anything like as good as The Black House.
Negative Space by Zoe Strachan & In Another Light by Andrew Greig both partly set in Orkney, both great writing.