A brief look at why all stories are, on some level, mystery stories
Once again, "How To Write..." is about something other than its ostensible title. I've never written a pukka mystery (although I've come close), so my advice is--not for the first time--of dubious value.
On Wednesday, my editor Will gave me the copyeditor's comments on The Dog of the North--another milestone out of the way. The copyeditor had told Will how much enjoyed the book (not always a given) and, even better, said it reminded him of Jack Vance. (Note to flatterers everywhere: this is the biggest compliment you can pay me. It's best when accompanied with familiarity with Vance's work, although even this is not essential...)
The copyeditor's detailed comments were generally straightforward. If the house-style is to write "marketplace" and not "market-place" I'm not going to hang myself over it. But there was one specific comment which was fascinating, even where I didn't agree with it. The Dog of the North is structured around two separate but interlinked narratives which do not converge until the end of the novel. The copyeditor noted that the relationship between the two narratives--particularly the temporal relationship--is not immediately clear, although certain aspects of it can be inferred. I could, he suggested, have made things clearer by a couple of sentences at an early point in the story. And so I could: it would be a very easy change to make.
The copyeditor outlined how the narratives had unfolded in his head, and at which point he had reached the key realisations. And it was exactly the way I had intended it. The novel has a number of key mysteries: one hidden (i.e. I'm doing something in the background I'm not telling you about) and one superficial. The superficial mystery is in making the reader ask: "why are you telling me two stories? how are they related?". And the alert reader, by picking up on the clues, can establish the answer before I tell them. By giving them a little puzzle to solve, I pique their interest and, with any luck, hold their attention.
The Dog of the North is not, in any conventional sense, a mystery novel. It does not stand or fall on how the puzzles in the text are resolved. But it's a mystery in the sense that all novels are mysteries. In all but the most experimental works, "what happens next?" is what keeps us reading. That can be as obvious as "will Poirot catch the murderer?", through "will Hamlet kill Claudius?" right the way through to "will Elizabeth marry Mr Darcy?" If you don't want to know what happens next, the writer hasn't written a story. Note, however, that that question doesn't have to be resolved in the expected way (most murder mysteries work by delivering the expectedly unexpected) or even at all (the ending of Great Expectations is crafted to allow two mutually exclusive readings, and the ending of The Italian Job works only because it doesn't resolve anything). And some endings resolve the central mystery, only to open another (Jack Vance frequently does this, and more recently L.C. Tyler's The Herring Seller's Apprentice closes off one mystery only to open up another).
So I've got two flippant pieces of advice for anyone who wants to know how to write a mystery. The first: write any story. Job done--you've written a mystery. Secondly, if you want to write a 'mystery' in the narrower genre sense: read The Herring Seller's Apprentice. It uses, and subverts, just about every trick in the book. If you can't see how it's done after that, you're beyond help.