The Detection Club: 10 Rules for Writing a Mystery

Founding members included legends like Agatha Christie, Dorothy L. Sayers, and E. C. Bentley, as well as G. K. Chesterton, who served as the first president. Meetings consisted of dress-up dinner parties, during which the old-school literati would swap writing tips and critique each other’s latest work. Like any legit society, they decided on new members by secret ballot, and each one had to swear an oath, written up by Sayers:

Do you promise that your detectives shall well and truly detect the crimes presented to them using those wits which it may please you to bestow upon them and not placing reliance on nor making use of Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence, or Act of God?

Related: A Case for Detective Short Stories

Once a member was sworn in, he or she had to abide by the group’s Ten Commandments when penning novels – or they were cast out of the clique. These “fair play” rules (still loosely used by the modern-day club) were meant to give the reader a sporting chance to solve the mystery along with the protagonist, but they’re also just really entertaining to read.

Next time you pick up your copy of Murder on the Orient Express, have this list handy to see how closely Christie abides.

1. 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.

2. All supernatural or preternatural agencies are ruled out as a matter of course.

3. Not more than one secret room or passage is allowable.

4. No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.

5. No Chinaman must figure in the story. [Editor’s note: At the time, trashy, mass-media mysteries always featured a character of Chinese descent. This rule meant the writer should avoid cliche plot devices, although yes, it sounds totally racist.]

Related: 11 Authors Like Agatha Christie

6. No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.

7. The detective must not himself commit the crime.

8. The detective must not light on any clues which are not instantly produced for the inspection of the reader.

9. 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.

10. Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.

[Via The Ronald Knox Society]