The detective story is a kind of intellectual game. It is more — it is a sporting event. And for the writing of detective stories there are very definite laws — unwritten, perhaps, but none the less binding; and every respectable and self-respecting concocter of literary mysteries lives up to them. Herewith, then, is a sort Credo, based partly on the practice of all the great writers of detective stories, and partly on the promptings of the honest author’s inner conscience. To wit:
1. The reader must have equal opportunity with the detective for solving the mystery. All clues must be plainly stated and described.
2. No willful tricks or deceptions may be placed on the reader other than those played legitimately by the criminal on the detective himself.
3. There must be no love interest. The business in hand is to bring a criminal to the bar of justice, not to bring a lovelorn couple to the hymeneal altar.
4. The detective himself, or one of the official investigators, should never turn out to be the culprit. This is bald trickery, on a par with offering some one a bright penny for a five-dollar gold piece. It’s false pretenses.