How to Plot A Mystery Novel

The Classic Approach to plot popular mystery fiction follows a fairly common formula. Some writers try to change the formula, but the ones who are published the most often stick to the following formula for good reason – because it works!

The following outline serves the modern mystery novel, as defined by the old style editors and trade publishers. A typical mystery will run 60,000 to 70,000 words (230 manuscript pages) and will be divided into 12 chapters, each approximately 17-19 pages in length.

Classic 12-Chapter Mystery Novel Formula

Act I
Introduction of the crime (mystery) and the investigator

Chapter 1

a) Disclose the crime and mystery to be solved. The crime must capture the imagination. It should have been committed in an extraordinary way and the victim, the perpetuator, or both, should be unusual. Give the reader enough information about the victim to make them truly care that the perpetrator is found out and that justice is served.

b) Early in the story, clues should be revealed which suggest both physical and psychological aspects of the initial crime. Those clues should point to suspects and motive which will carry the investigator to the end of Act I. Some clues should point the investigator in the right direction; others may not be obvious or be recognized as actual clues unto later in the story.

c) Introduce the investigator who’ll solve the crime early, and have him or her do or say something very clever or unexpected which will establish that person as unique. Create this character with care. His or her personality should be interesting enough to sustain the interest of the reader to the very last page. (or through a series of books). It’s not necessary to disclose all aspects of the investigator’s personality at the onset. Let the description unfold gradually to sustain interest. Reveal just enough background to let the reader understand the world in which the protagonist functions. (Small town sheriff, New York City detective, Scotland Yard investigator, Pinkerton agent in the old West, private investigator, bounty hunter, investigative reporter, etc.)

d) Put the reader in the time and place where the crime occurs. It is often useful to include some sort of symbol, an object or a person, in the opening scene which serves as a metaphor for what occurs in the story. The reappearance of this symbol at the conclusion of the story will create an organic unity.

e) Begin with a dramatic event. Some writers offer a prologue, describing the execution of the crime in detail, as it occurs, possible from the point of view of the victim or criminal. The same information could also be revealed by a character, through dialogue. Sufficient details should be furnished to allow the reader to experience the event as though he or she were actually there. Another good opening would be to put the investigator in a dire situation and allow detail of the crime to unfold in due course.

Chapter 2

a) Set the investigator on the path toward solving the mystery. Offer probable suspects, all of whom appear to have had motive, means and opportunity to commit the crime. Select the most likely suspects, and have the investigator question them. One of these suspects will turn out to be the actual perpetrator.

b) At the approximate mid-point of Act 1 (the first plot point – about 25% the way into the story), something should happen which makes it clear to the reader the crime is more complicated than originally thought. Hints may be given to allow the reader to actually see possibilities not yet known to the investigator.

Chapter 3

a) The sub-plot should be introduced. The plot will continue to maintain the progress of the story, but the sub-plot will carry the theme, which is a universal concept to which the reader can identify. Sub-plots tend to originate either in a crisis in the investigator’s private life, or in the necessity of the investigator to face a dilemma involving a matter of character, such as courage or honesty.

b) The ultimate resolution of the sub-plot will demonstrate change or growth on the part of the protagonist, and will be climatic on a personal or professional level. That climax may coincide with, or occur as prelude to the climax of the main plot. The sub-plot may be a vehicle for a romantic interest or a confrontation with personal demons of the investigator. The author can manipulate the pace of the novel by moving back and forth between the plot and sub-plot.

Act II

Direct the investigation toward a conclusion which later proves to be erroneous.

Chapter 4

a) Reveal facts about suspects, through interrogations and the discovery of clues.

b) Flight or disappearance of one or more suspect.

c) Develop a sense of urgency. Raise the stakes or make it evident that if the mystery is not solved soon, there will be terrible consequences.

Chapter 5

a) The investigation should broaden to put suspicion on other characters.

b) Information gathered through interviews or the discovery of physical evidence, should point toward the solution, although the relevance may not yet be apparent.

Chapter 6

a) The investigator’s background is revealed as the sub-plot is developed. Tell the reader what drives the protagonist, what haunts or is missing in his or her life.

b) Make it clear that the investigator has a personal stake in the outcome, either because of threat to his or her life, or the possibility of revelation of matters deeply disturbing to the protagonist on an emotional level.


Change of focus and scope of the investigation. This is the pivotal point (mid-point 50% the way into the story) in the story where it becomes evident that the investigator was on the wrong track. Something unexpected occurs, such as the appearance of a second body, the death of a major suspect, or discovery of evidence which clears the most likely suspect. The story must take a new direction.

Chapter 7

a) Reveal hidden motives. Formerly secret relationships come to light, such as business arrangements, romantic involvements, scores to be settled or previously veiled kinships.

b) Develop and expose meanings of matters hinted at in Act I., to slowly clarify the significance of earlier clues.

Chapter 8

a) The investigator reveals the results of the investigation. The reader, as well as the protagonist and other characters, are given an opportunity to review what is known and assess the possibilities.

b) The solution of the crime appears to be impossible. Attempts to solve the crime have stymied the investigator. Misinterpretation of clues or mistaken conclusions has led him or her in the wrong direction, and logic must be applied to force a new way of grasping an understanding of the uncertainties.

Chapter 9

a) Have the investigator review the case to determine where he or she went wrong.

b) Reveal the chain of events which provoked the crime.

c) The crucial evidence is something overlooked in Act I, which appeared to have been of little consequence at the time it was first disclosed. That evidence takes on new meaning with information disclosed in Act III.

d) The investigator (and perhaps the reader, if a keen observer) becomes aware of the error which remains undisclosed to the other characters.

Act IV – Solution

Chapter 10

a) The investigator weighs the evidence and information gleaned from the other characters.

b) Based on what only he or she now knows, the investigator must seek positive proof to back up the yet undisclosed conclusion.

Chapter 11

a) Resolution of the sub-plot

b) The protagonist, having been tested by his or her private ordeal, is strengthened for the final action leading to the actual solution of the mystery (third plot point – 75% of more into the story).

Chapter 12

a) The Climax – a dramatic confrontation between the investigator and the perpetrator in which the investigator prevails. The more “impossible” the odds have been, the more rewarding the climax will be.

b) Resolution – Revelation of clues and the deductive process which lead to the solution. Establish that the case has been solved and justice has been served to the satisfaction of all involved (except, the villain).

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4 thoughts on “How to Plot A Mystery Novel

  1. Tanya says:

    I wanted to say thank you for this!!! It has been incredibly helpful to me as I have been outlining my story to gear up for this years NaNoWriMo. This is my first attempt at trying to write a murder mystery, so at times I felt completely lost. The details you have given were very helpful in putting me back on the right track with my story. Again, many thanks!

  2. Angie says:

    This is really great! It really helped me get focused for this year’s nanowrimo!

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