From what viewpoint will the reader see your story unfold? Will it be through the sleuth's eyes as he tells his own story? ("As I walked to work that day, thinking about my....")
Or will his story instead be told by a voice outside of him? ("As he walked to work that day, thinking about his...")
Or will there be several viewpoints, possibly of people on a collision course? (Again: "As Dashiell walked to work that day, thinking about his..." but later, in a new scene, "As Agatha walked to work, thinking about her...")
Those are your primary options, quite rationally called "Points of View,"and the point you pick dictates what can be seen and known. Each has strengths and weaknesses to consider.
First person ("I") comes naturally to us. It's how we've been telling stories all our lives, and because of that, it rings true to the reader. We're conditioned to believe that someone (even a fictional someone)saying, "This is what happened to me," is telling the truth, or at least his version of the truth.
Another plus for first person is its ability to bring your narrator to life through a distinctive voice. We filter everything through your protagonist's literal and figurative world-view as he speaks to us, so you can—and should—make his language, his opinions, and his general take on people and events vivid, unique and memorable.
If you're writing in first person, you must live within your narrator's skin, seeing only what he can see. You can't say, "As I walked to work, I blushed..." because your narrator can't see his own cheeks. You could say "I felt my face heat up" (or whatever symptoms of blushing your character feels), but throughout the book, you can't be anywhere but right inside your character, wherever he is.
Even though first person lessens the ultimate suspense because it's obvious the narrator lived to tell his tale, it's a traditional voice for mysteries because being confined inside one mind means you can maintain tension, keeping your story's meaning as mysterious to the reader as it is to your narrator. The flip side is that this same confinement narrows plot options. This is not said to discourage you, simply to say you have to plant clues that illuminate what happened while your narrator was elsewhere—but not, please, via the cliche of having him pick up a phone, open a letter,or pass an open window just as the villain explains himself in full.
Most often, the first-person narrator is the detective (in a mystery), or the person in jeopardy (in suspense), but sometimes a secondary character narrates. Dr. Watson tells us Sherlock Holmes' exploits, and Archie Goodwin does the same for Nero Wolfe, and it works because both of them work with/for supernaturally bright and abnormally inert, stay-at-home detectives. Watson and Goodwin leave home, provide necessary action and interaction and act as go-betweens for the genius and the reader, asking the questions we also have and thereby "translating" their employers' ideas for us. If you're writing a similar duo, then consider having your Archie or Dr. Watson—the more active and engaged character—as your narrator.
Your other option is third person, where instead of having your character tell his own story, you observe him and tell his story for him. It's as if we put listening and viewing devices everywhere your character might be,even inside his head, and then we turn on all or only some of the bugging devices.
If you only use the eavesdropping apparatus that is outside of your observed character, you'd be using an "objective third person" point of view, recording only what a camera could see. And, in fact, this variety of prose often reads like a script. (E.g., "He walked to work. A man in a fedora approached and asked him why he was scowling...") You can't tell us what the character thinks, so this viewpoint forces you to show everything through actions and dialogue. This makes for an interesting and valuable writing exercise, but doesn't allow you to use the writer's x-ray vision to read minds or hearts. Nonetheless, the trade-off was worth it to Dashiell Hammett—check The Maltese Falcon for an example of objective writing.
More commonly, we use all the listening apparatus we can, and we overhear the point of view character's thoughts and feel his emotions. (E.g., "He walked to work, head pounding as he thought about the muddle his life had become. It's all her fault, he thought...") Sometimes, you plant that listening device so far inside your character's head that we hear his thoughts along with him and don't need "he thought." Using the same unfortunate character about to be smashed by a truck,you might write, "He walked down the street, head pounding as he thought about the muddle his life had become. All her fault. Every bit of it. A gigantic truck turned the corner and..."
You can use multiple third person voices, focusing on more than one character. For example, to torque up the suspense in a thriller, you might want to be able to enter the victim, the villain and the detective's points of view. The reader becomes intensely involved because he knows more than any one character does, and even if a character is oblivious of it, this reader sees the big picture of escalating danger. But—this is important—keep to one point of view per scene. Your reader is the point of view character within any given scene. Don't ruin the suspense you're building by leaping into another mind during any given scene.
If you use multiple points of view, signal your reader as to whose sensibility we're in early in each scene or chapter switch. This is easily done in the first line or two: "The room was hot. Jane felt sweat on her forehead and thought..." We're in her thoughts, we're feeling her sensations—you've told us we're in Jane's point of view till further notice. The next chapter might begin with, "Harold thought he'd never heard as funny a joke." And we know we've received further notice—we're now in Harold's point of view. Also, in deciding which point of view to use in a given scene—go with that of the character with the most at stake right then. This will build suspense and tension and keep your reader interested.
Have fun seeing through your characters' eyes.
Next lesson: Making your reader care.
Adapted from: You Can Write a Mystery, by Gillian Roberts.
© Gillian Roberts.