The gist of any mystery is this: a character needs to find the answer to an unknown. Even though the definition is simplistic, the composition requires skill. Here are eight steps to creating a tantalizing mystery.
The board game Clue demonstrates this concept. At the outset of the game, three cards are isolated from the others. These cards are put into an envelope marked "Case File CONFIDENTIAL" and are set aside. The three cards designate who committed the crime, where, and with what weapon. The game would be changed significantly if those cards were not chosen at the beginning. Players would just randomly pick criminals, crime scenes, and weapons. The ending would be one big mess.
That same principle applies to your mystery or detective story. Everything – all dialogue, characters, events, and actions have to be set up in advance to create a logically progressed story.
Your mystery should elicit anxiety in your audience as they are drawn deeper into your story, eagerly awaiting the outcome.
The crime and setting has to be appropriate for the tone of the story. There is a difference between The Pink Panther and A Soldier’s Story. In The Pink Panther, the inspector tries to uncover a jewel thief and relies heavily on comedy. In A Soldier’s Story, a military investigator tries to discover who killed a sergeant and deals segregation in the Deep South.
Remember, if the tone is light, the crime should be light. If the tone is dark, keep the crime dark.
One of these clues should be crucial and is the piece of information that helps the detective or detective-type character solve the mystery.
Strategically place red herrings to mislead readers by making them suspect the wrong characters.
At the outset, begin with action, suspense, or some other attention-getter. One of the best ways to do this is to start with the crime itself.
Subplots usually give the sleuth emotional, social, or relationship issues to deal with. These new conflicts add flavor to an otherwise one-dimensional story.
Audiences long for an ending that makes them squeal, “Wow, I would have never guessed he did it!” But with 20/20 hindsight, the audience can clearly see the clues and the outcome makes sense.