Top Rules for Mystery Writing
More than any other kind of genre writing, mystery writing tends to follow standard rules. It is because readers of mysteries are looking for a particular experience. These readers are looking for the intellectual challenge of solving a crime before the detective does, and they want the pleasure of knowing that everything will come together in the end.
Of course, the best way to test the rules of mystery writing is to read many books in the genre. This way you can see how other writers use the rules, and how they're able to get away with breaking them. But before you attempt to break the rules, read the rules below and see how your work adheres to the rules, and how it deviates from them.
In Mystery Writing, Plot is Everything
Introduce the Detective and the Culprit Early On
Introduce the Crime in the First 3 Chapters
The crime and the ensuing questions are the hooks that will engage the reader. As with any fiction, you want to introduce these as soon as possible.
The Crime Should be Violent, Preferably a Murder
For many readers, only murder justifies the effort of reading a 300-page book while suitably testing your detective's powers. However, it's worth noting that other types of violence (such as rape, child molestation, and cruelty to animals) are taboo enough to warrant a mystery novel.
The Crime Should be Believable
While the details of the murder (i.e., how, where, why, and how the crime is discovered) are your main opportunities to introduce variety, make sure the crime is plausible. Your reader will feel cheated if the crime is not something that could take place.
The Detective Should Solve the Case Using Only Rational and Scientific Methods
Keep in mind this oath written by G.K. Chesterton for the British Detection Club, "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 on them and not placing reliance on nor making use of Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence, or Act of God?"
The Culprit Must be Capable of the Crime
It sounds like a no-brainer but keeps in mind that your reader must believe your villain's motivation. And, the villain must be both physically and emotionally capable of the crime.
Don't try to Fool the Reader
Again, being implausible takes all the fun out of it. Don't use improbable disguises, twins, accidental solutions, or supernatural solutions. The detective should not commit the crime. All clues should be revealed to the reader as the detective finds them.
Do your Research
Mystery writer Margaret Murphy says, "Readers have to feel you know what you're talking about." Murphy has a good relationship with the police in her area and has spent time with the local police forensic team. Make sure you nail all the essential details.
Wait as Long as Possible to Reveal the Culprit
People are reading to find out, or figure out, the whodunit. If you provide readers with the answer too early in the book, the reader will have no reason to continue reading.