Writing a mystery, or any novel for that matter, has three major components: plot, character, and setting. Depending on the personality of the writer, one or maybe two of the three components are easy. It’s the other one that gives us fits.
I’m going to talk about plotting because it’s my strong suit. Developing characters, and especially revealing their emotions, is tough for me. Describing settings is also a bear. But because I’m a concrete sequential thinker, plotting is easy.
I’ve developed what I call the ABC method of plotting my mysteries. Plot A is the main plot of the whole book. Someone gets killed. The protagonist follows the clues and chases down the killer. The mystery is solved. Plot A involves leaving clues that point to the killer as well as to the red herrings. Eventually Plot A leads the hero(ine) and the reader to the correct solution of the mystery. Plot A develops along essentially a straight line from beginning to end.
Plots B and C are the subplots. I plot each one as though it was a separate novel. Maybe the protagonist has a love interest that develops over the course of the book. Or she has a job/interest/pursuit that she is following. The murder and its solution take place within the context of the protagonist’s lifestyle.
In my novel, Dangerous Turf, the heroine lives and works on a racetrack where she is struggling to become a successful jockey. The murder victims are track workers. While she is trying to achieve her goals and compete in a male-dominated sport, she is also trying to solve the murders. She also has two love interests.
In Dangerous Turf, Plot A is the murder mystery. Plot B is her struggle to compete. Plot C is the love angle. B and C are interwoven throughout A, crossing and intertwining as the whole book proceeds. Of course, all three plot lines have to be resolved at the end.
Subplots are what make the protagonist interesting, make him more human. All the great detectives, for example, have something about them that endears them to the reader while they are solving murders and mysteries. This is why a mystery novel often turn into a series. Readers want to know more about the protagonist, not just his methods of crime-solving, but the drama of his life.
Sherlock has a problem relating on a human level. He is frequently bored and turns to drugs to deal with this boredom. Dorothy Sayers took full advantage of this in her Lord Peter Wimsey novels. The romance between Peter and Harriet Vane was the hook that kept readers clamoring for more. Each book had a different Plot A, but they were almost overshadowed by Plot B, the love story.
When I start out to write a mystery novel, I think through Plot A first, writing down a series of events that lead to the resolution. Then I put each event in its proper sequence. Then I plot B and C. Weaving them all together is easy once you’ve decided on the sequence of each plot. But, then again, I’m a sequential thinker. It’s going to be harder for the random abstract thinkers. Each writer has to find the method she is most comfortable with, the one that produces the most engaging story.