There is a story in Flyaway called “The Sawmill”.
The setting was inspired by a decaying set of sawmill buildings on a sliver of land that would have once belonged to the corner of our property (I did confirm I could go out there!).
I drove back out that way when I was editing Flyaway — checking my memories and taking notes. I found the overgrown gate and climbed over and walked through the trees the same way “Jack” returns in the book.
It was both far closer than I remembered and much, much further.
The day was bright and the dry grass cracked. There was no phone reception and the buildings had… changed. The old detritus had been cleared out. There were a few boxes there with things left over from other people’s lives. A few chairs, although they could not be sat in, were arranged on the porches as if someone had been sitting there a few moments before.
And of course in the years since I’d last been there, I had written the story that became that chapter of Flyaway. I was alone in the loud bush, and while my memories of the sawmill were of adventure and the treasure to be found in stored boxes, my adrenaline response had been pretty well appropriated by my imagination.
It didn’t even need to be dark.
Horror that describes horrible things in great detail (or with just enough to let your imagination do the work) is of course dreadfully effective. But for uncanny horror, I’ve found the process strongest (on the writer, if not the reader) if I begin with something towards which I feel affection, and ask but what if it were fearful? It adds an extra layer, the sense of something you love turning to show a face you don’t know, the feeling of a dog’s head beneath your hand but instead of a welcoming movement an “absolute stillness”.
The sawmill, a garden, a friend; good manners, a gate, a line of poetry. And then: but what if this were not all it seems, what if it were used for ill, what if there were something else sharing that space, or beneath it, or in its eyes, or watching from the trees…
Edit: Edited to fix the link to M. R. James’ “The Diary of Mr Poynter”. James does this sort of thing extremely well, and his stories have left me looking suspiciously at things like leather bags and bedsheets.