(by Ronald Knox)
- The criminal must be someone mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to follow.
- All supernatural or preternatural agencies are ruled out as a matter of course.
- Not more than one secret room or passage is allowable.
- No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.
- No Chinaman must figure in the story.
- No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.
- The detective must not himself commit the crime.
- The detective must not light on any clues which are not instantly produced for the inspection of the reader.
- The stupid friend of the detective, the Watson, must not conceal any thoughts which pass through his mind; his intelligence must be slightly, but very slightly, below that of the average reader.
- Twin brothers, and doubles, generally, must not appear unless we have been duly prepared for them.
It’s always fun to get someone else’s take on how to write a certain genre. I write suspense thrillers, and my Tazia Bates mystery series does have a detective in it. I do tend to violate his rule #2, though. Supernatural aspects are in all of my stories.
I hope you’ll follow me at http://sherrybriscoe.com