One of the most challenging aspects of writing a mystery novel is advancing the plot in a way that keeps readers guessing but doesn’t leave them feeling deceived by red herrings and hidden clues. One of the best ways to meet this challenge is to flesh out your protagonist, or detective, before you establish the plot of the novel. If the detective, whether professional or amateur, emerges from the page as a fully developed and unique person, the reader will more readily accept the twists and turns because the detective is solving the mystery in the only way he or she can.

For example, the protagonist of my upcoming mystery novel, Mayor of Hollywood, is a famous actress named Lucy Cassidy. Her background enables her to immediately recognize that a suspect has lied about what is normal behavior on a film set, but it also means that she misses some subtler clues because she is used to dealing with larger than life personalities. Her unique perspective informs how she investigates the murders, allowing her to pursue leads in her own way.

Since the most important part of a mystery novel is the mystery, writers often skip right to plot development, drawing the protagonist in broad strokes. However, this can lead to credibility problems since the detective must make discoveries in a certain order simply because that is the way the plot says that the mystery unravels.

Imagine, for example, a scene in which your homicide detective protagonist breaks into a suspect’s house and discovers a fresh body. Why did the detective risk her career entering a private home without probable cause or a warrant? The answer cannot be because the plot requires that the body be found at this point in the book. But think about some of your favorite fictional police detectives. Would John Rebus break into a house without a warrant? Probably. Harry Bosch? Maybe. Peter Decker? Not unless he thought Rina or one of his kids was in there. We can speculate about what they would do because they are well developed characters with clear points of view. As such, they have the ability to drive the plot, rather than letting the plot drive them.

So how do you set about developing your detective? You must start before you have more than the basic sketch of the mystery. Establish, of course, whether he is a police detective, federal agent, private investigator, or something else entirely. Then, dig deeper. What was her childhood like? Is he single, married, or divorced? How did she choose her career? Is he a lone wolf, like John Rebus? A team leader, like Peter Decker? Or something in the middle, like Kinsey Millhone?

Don’t underestimate the importance of apparently small details. For example, Lucy Cassidy is very intelligent, but she was also raised by a controlling stage mother. Her resulting resistance to letting other people control her actions causes her to periodically take risks she knows she probably shouldn’t. She doesn’t go into dangerous situations alone because the plot requires it. She does so because her personality compels her.

Character development worksheets can seem overwhelming and needlessly detailed, but I encourage you to use them at least for your protagonist. Once you know your private investigator is a vegan, a widower, an expert chess player, and dozens of other things, you’ll be surprised by the exciting ways that your plot outline unfolds. Don’t be afraid to make unusual connections. Kinsey Millhone, for example, doesn’t have claustrophobia from being trapped in a wrecked car at a young age. Rather, she is drawn to small, cozy places, and that approach has allowed Sue Grafton to write some really evocative scene descriptions. Just because most vegans find meat unappealing, that doesn’t mean yours can’t salivate at the smell of a steak. Real people are a bundle of seeming contradictions, so give your detective some surprising traits and see where they lead you.

Once you have a fully fleshed out character, outlining your mystery will be much easier. You can simply ask yourself at each step: WWMPD? (What would my protagonist do?)

Good luck!