Here are the last five of Robert Knox’s 10 Rules for Detective Fiction from the Golden Age of Mysteries.
Rule #6. “No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.” Personally I don’t mind the occasional accident helping to unmask a killer. After all, bizarre events do happen in real life. (Just ask me about my last two years, for example...) I’ll also accept some intuition, mostly in amateur female sleuths. We’re rather known for it, after all. But it must be born out by the facts of the story, which the detective must unearth before the end. What I personally don’t like is smugness on the part of the detective who has a perfectly good reason for suspecting someone, but refuses to reveal it. That's is another reason Sherlock Holmes will never be my favorite guy, though I like some of the stories about him a lot. The Speckled Band, for example. Come to think of it, there is a kind of a secret passage in that story, and another favorite, Hound of the Baskervilles, appears to have a supernatural element to it, (rules #2 and 3.) There may be a trend here...
Rule #7. “The detective himself must not commit the crime.” I like this rule, because it keeps me from feeling the need to peek to the end of the book, just to be sure I can trust what I'm reading. I did once read a book where the criminal turned out to be the sleuth, and I was thoroughly disgusted when I realized I had been tricked that way. Without trust between the writer and audience, reading becomes too much of a mine field for me to enjoy. I’ve never been a big fan of the kind of speculative fiction that keeps me off balance while I’m reading. Too much like real life, perhaps? No, part of the appeal of a mystery is the sense of write and wrong in these stories. Just like in a real western, there must at least one good guy, and I want to know who he is.
Rule #8. “The detective is bound to declare any clues which he may discover.” No more scenes of the detective slowly unfolding a piece of paper, turning it to the light to read it more clearly, then -- folding it back up and sticking it in his pocket. A real man, or woman, shares his clues!
Rule #9. “The stupid friend of the detective, the Watson, must not conceal from the reader any thoughts which pass through his mind: his intelligence must be slightly, but very slightly, below that of the average reader.” Now these are Robert Knox’s words, not mine. But let’s admit it, Watson can be very dense sometimes. I used to worry about his patients, wondering if a man as slow as he was could really be a decent doctor. Fortunately, his physician/neighbor spends so much time covering for him, is patients were probably pretty safe.
Rule #10. “Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.” Or even then. I mean, really. What kind of self respecting mystery writer relies on a body double, twin, or long-lost relative to make their case? In the same vein I dislike undisclosed marriages, innocent looking people who turn out to have worked for the SS or MI-5, and secret wills. In Ngaio Marsh’s The Final Curtain, Sir Henry Ancred has the details of his new will read aloud. When his subsequent death is explained by the existence of a quite different version he had drawn up at the same time, I always cry “Foul.” Mysteries are supposed to be full of lies, cheats, and trickery -- but that’s supposed to be the criminal, not the writer or the sleuth. After all, it can be a scary world out there, and a girl needs to have someone she can trust.
Read Well, Friend