Over the years since Edgar Allen Poe introduced the mystery story as we know it, "rules of the game" have developed. By following such rules (or breaking them artfully), writers meet the expectations of mystery readers and “play fair”. Here are the rules:

  1. In its basic structure, the detective story must never vary from being absolutely logical.
  2. A completely unpardonable sin is the substitution of accident, chance, or coincidence for logical deduction.
  3. The detective story must always play fair: no evidence can be made known to the reader which remains unknown to the detective, and vice-versa.
  4. All action must proceed from the central theme of the crime and the pursuit of the criminal.
  5. No human frailties, like stupidity or a poor memory, can change or prolong the plot in any way.


There are some secondary rules:

  1. The crime must be murder.
  2. the killer's motive must be strong enough to induce an amateur to commit murder
  3. all suspects must be real suspects, the killer must be one of the suspects (don't bring in a new character at the end)
  4. the murder must be pre-meditated, or if it is a crime of passion, or unintended, it must be ingeniously covered up.
  5. the killer should be an intelligent, competent amateur, the crime elegantly planned which, except for the brilliant detective, would go unsolved.
  6. clues should be clearly presented. All information given to the detective must be given to the reader. This is called "Fair Play." [similar to #3 in the section above, with the addition of ‘clearly presented’]
  7. the detective is not superhuman but uses reasoning to fit the clues together


These are not rules, but nice to have:

  1. the detective is fun if unusual, fallible, and has personal problems.
  2. lead characters should grow and change
  3. the detective should have a profession that allows him/her to spend time, money, and energy on the crime
  4. don't treat police as idiots
  5. don't make the victim an angel or the killer thoroughly evil.
  6. the killer must be an amateur who has not killed before and does not plan to kill again - no serial killers, psychos, random killings (unless it's a police procedural).
  7. the story must be moral in that BAD is punished, GOOD rewarded, and the universe is restored to harmony and balance
  8. in the classic whodunnit, the killer should be near the victim, and use an ordinary means
  9. it is desirable for the murder to occur early in the story so the puzzle is whodunnit, not when-will-the-writer-get-down-to-business.
  10. It helps if there is a deadline to beat; a "ticking clock"


[for more classic ‘rules’, look up “S.S. Van Dine’s Mystery Rules]


Classic Mystery Basic Backbone

(the numbers are not chapter numbers, simply points to consider)

ACT I (hook; setup of the mystery)

  1. A killer opening: a grabber “inciting incident” that shows the person whose life is about to be upset
  2. Introduce the protagonist, probably the sleuth (if you didn’t do so in the grabber)
  3. Introduce the victim and criminal
  4. Introduce a subplot: the main character’s or a secondary one, or both
  5. Murder scene and clues: who finds the body, how, initial observations
  6. End with a crisis: a big decision/discovery that leads to a goal and commitment to it
  7. No flashbacks!


ACT II (complications, discoveries, reversals, 2nd crisis; setup of the ending)

  1. Develop suspects and interrogations
  2. Lay down/gather clues, including lab evidence, information providers
  3. Introduce/develop subplots: love interests, rivals, allies, private problems
  4. Flashbacks allowed here, but only to explain/illuminate the present
  5. Raise the stakes: make the case personal, the consequence of failure high
  6. Conclude with major discovery/reversal/setback that…
  7. Causes a second crisis: a deadline to meet, a ticking bomb, a low point that threatens success


ACT III (the payoff)

  1. Eliminate suspects
  2. Chief suspect disappears or is killed
  3. Zero in on the criminal
  4. Pieces come together, time becomes a problem, put protagonist in danger
  5. Confrontation with the criminal: the Showdown. Good v. Evil and only one wins
  6. Resolution: criminal arrested, killed, escapes, or?



  1. Explain clues and connections not clear yet
  2. Show how main character has been transformed
  3. Resolve subplots in a way that shows how they support main plot
  4. Kicker: a small, symbolic action; a ‘curtain line’ of dialog; something that echoes the beginning

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