How to Write a Mystery Novel That Sells

Introduction
The mystery novel is among the world's bestselling and popular genres. The hallmarks of a good mystery story are a sympathetic protagonist, a mind-taxing puzzle to solve, nail-biting tension, and a thrilling finale. Done well, it's a genre that keeps readers on the edge of their seats, eagerly turning pages to uncover the truth behind a crime. Crafting a successful mystery novel requires careful attention to various elements that make the story interesting and keep the reader emotionally and intellectually engaged, immersed in the fictional world you've created, and desperate to find out what happens next. In this post, we'll uncover the mysteries of mystery writing and explore the essential components of a successful mystery novel to give you helpful and actionable tips on how to write one.

What is the mystery genre?
Before delving into the intricacies of writing a mystery novel, it's crucial that you understand the defining points of the genre itself. Almost all mystery novels revolve around the central fact of solving a crime or unraveling a series of crimes. The most common crime is a murder. But the crime may also be a kidnapping, a theft, or drug smuggling, for example. Most also have a single, key protagonist—often a professional detective or amateur sleuth—with whom the reader can identify and through whose eyes and experience, the reader becomes an active participant, working alongside the protagonist to uncover clues and reveal the identity of the culprit.

Contemporary mystery writers include Michael Connelly, Nicci French, Lee Child, Tess Gerritsen, Harlan Coben, and even Richard Osman. Successful mystery stories often feature a detective or protagonist who employs deductive reasoning, logical analysis, or intuition to solve the case. Mystery novels can be set in various environments, from quaint villages to bustling cities, offering readers a glimpse into the dark side of human psychology and society.

The 10 essential elements of a good mystery novel
To create a successful mystery novel, you must incorporate several essential elements. These elements will engage readers and keep them invested in the story from beginning to end. So, let's explore these crucial components that will help you write a novel that readers cannot put down.

1. An opening hook
The opening of a mystery novel is vital in capturing the reader's attention and giving them reasons to keep reading. The story should start with events, dialogue, and characters which raise intriguing questions in the reader's mind. This is called “the hook”. In most mystery novels, it will be the discovery of the crime—often the body of the murdered victim, or the appearance of a central character who describes the core puzzle. But of the opening pages, the most important is the opening paragraph, and of that, the opening sentence. Here's a quick example of what we think is one of the great opening sentences from any mystery novel. It's from No Second Chance, by Harlan Coben, which starts with the sentence, “When the first bullet hit my chest, I thought of my daughter.”

Even though we still don't know who the narrator is, this sentence throws us straight into the action and raises several questions in the reader's mind: Who is speaking? Why have they been shot? Who pulled the trigger? Who is his daughter? How many shots were fired? We also feel immediate empathy for the narrator because his or her first thought is for their daughter. And the use of the first person narrative viewpoint shows us that the narrator has survived being shot (or how could they be writing this now!) which raises further questions: How did they survive? What happened next? Is their daughter safe? It really doesn't get much better than that. It would be a very indifferent reader who wasn't compelled to read on.

2. A protagonist we can root for
A good mystery novel requires a likable and relatable protagonist who serves as the detective figure. They don't need to be a professional detective or police officer, although they often are. But they may also be of the “amateur sleuth” variety. In modern mysteries, they are often reluctant to get involved at first, but forced by circumstances or an unexpected personal tragedy to unravel the mystery. This character should possess intelligence, wit, and the ability to solve complex puzzles. Readers should root for the protagonist and feel a connection to their journey, making them emotionally invested in the mystery's resolution.

3. A protagonist with depth and authenticity
But your protagonist should not be perfect. It's essential that they have a flawed personality and that, in other circumstances, they might themselves have succumbed to the darker side of their nature. Without this deeper aspect of their character, it's hard to create a detective who seems authentic and believable. Having a flawed protagonist also helps to introduce themes of conflict and transformation, which are essential to any good story, whatever the genre.

The best “detectives” in mystery stories struggle with the tension between their good intentions and their personal demons. Think of Sherlock Holmes's misogyny and addiction to cocaine, Hercule Poirot's narcissistic vanity, Adam Dalgleish's depression, or Philip Marlowe's alcoholism and tendency toward violence, just as a few examples. But—unless you want to create an antihero protagonist—make sure that your detective figure struggles with and overcomes these character flaws and doesn't just give in to them. They needn't be people that we'd like in real life, but in your novel, we, the readers, need to feel empathy for them; we need to believe that they have depth and authenticity.

4. Sidekicks and supporting cast
Besides the protagonist, a mystery novel should feature a cast of well-developed supporting characters. These will be the suspects—which should be almost everyone but the detective!—and, not least, a “sidekick”. The sidekick is a character close to the protagonist who serves as a bridge between the readers' average intelligence and the genius of the detective hero, as well as providing a balancing and protective role to the protagonist's deeper flaws. Think of Sherlock Holmes's Dr. Watson, Inspector Morse's Sergeant Lewis, or Lord Peter's Bunter. Each character should have their own unique personality and motivations, contributing to the overall depth and authenticity of the story. Supporting characters can serve as allies or suspects, adding intrigue and complexity to the narrative.

5. The murderer/criminal and the antagonist
While the murderer or criminal and the antagonist are often the same character, they needn't be. For example, in many of the best Holmes stories, the murderer exists only to be caught; the real antagonist, the one who holds up the progress of the brilliant detective's investigations, is often Inspector Lestrade of Scotland Yard or some other character who disapproves of Holmes and his methods. In other stories, Professor Moriarty combines both roles.

However you handle it, your mystery story must have a criminal and antagonist who is as wicked as the protagonist is good and just as smart, if not smarter. What finally causes their downfall, other than the detective's intelligence and dogged determination to bring him to justice, is his own flawed personality—which often mirrors that of the protagonist. The crucial difference is that the protagonist struggles with and overcomes his flaws in order to see the crime solved and justice done, whereas the antagonist succumbs to his faults and finally reveals his true nature.

6. A plot of twists and turns
The plot of a mystery novel should grip and fill with suspense. It should keep readers on their toes, eagerly turning pages to uncover the truth. Whether told in the first or third person, the storytelling should maintain a balance between providing enough information to engage readers and leaving room for speculation and anticipation. We divide most writers into those known as “plotters” and those called “pantsers”. Plotters develop detailed, structured outlines of every act, scene, and plot twist before they write. Pantsers (who, “write by the seat of their pants”) tend to just start and see where their story takes them. For writing a good mystery novel, our advice would be to plan everything carefully first.

Because a mystery or crime story isn't just a normal plot—it's a logical puzzle in which you need to place clues and “red herrings” with great care—you have a much higher chance of success if you plan it in advance. That doesn't mean you can't still be creative in your writing, characterization, and emotional color; of course, you can. But with a mystery, it's vital that you give away enough detail to keep the reader convinced they can figure out the solution before the detective, but not so much that they actually can! And that, you'll find, takes careful planning. But remember that all your plot twists and surprises must be logical, entirely believable within the framework of the story. If you throw in a surprise at the end that no-one could have figured out (such as a new character never mentioned before, or a vital item or piece of information which was never referred to or hinted at until that moment) your readers will feel cheated rather than surprised.

7. Believable dialogue
Effective, believable dialogue is crucial in immersing readers in the mystery novel's world, revealing character, and dropping both real clues and misleading red herrings. Well-written conversations between characters can reveal important information, provide insights into their personalities, and propel the plot forward. Dialogue should be natural-sounding, authentic, and serve a purpose in advancing the story.
In real life conversations, we stop and start, “um” and “ah” and express ourselves fairly incoherently! In written dialogue, natural-sounding doesn't mean to imitate natural speech properly – it would be unreadable! – so much as to create a rhythm and cadence in the dialogue that suggests a natural flow of conversation while actually being structured with care. Written dialogue should always be neat and succinct without sacrificing the recognizable “voice” of each character. Each speaker should be recognizable immediately by their dialogue with no constant explaining, “said Thomas”, “Alice sighed,” etc.

8. The slow burn
A successful mystery novel won't only be an intellectual puzzle. It should have a strong emotional engagement as well. This means building in plenty of conflict (which may be understated; psychological conflict rather than outright fisticuffs) and a slow-burn escalation in tension. A classic method is to introduce further crimes or murders at crucial moments in the plot's development. So, just when we—and the detective—think that we're closing in on the murderer, the suspect we think did it is also murdered. Or, a near miss attempt is made on the life of either the detective or their sidekick, for example. Throw in plenty of potentially suspicious behavior by all the characters as you build the tension. Closed room dramas which have a threatening, claustrophobic atmosphere with an invisible threat are another great way to make sure there's plenty of conflict and tension to keep the readers turning the pages.

9. A surprising but satisfying ending
As you'll have figured out by now, your mystery novel's plot has two levels: solving the crime and following the development of the protagonist. You could call these two levels the external plot and the internal plot. Whether the detective resolves their inner struggles by the end depends on what you have in mind in the future. If you want to write a standalone novel, then you'll probably resolve everything on the last page. If you aim to produce a series of mystery novels revolving around the same protagonist, then you'll want to resolve the external plot (solve the crime) but leave the detective's inner struggles still alive and kicking.

In terms of the outer plot, the final resolution should be both surprising (i.e., the reader didn't see it coming) but also satisfying (so that all the clues add up and the reader is left feeling that they could have solved the problem themselves). Never resolve a mystery plot by introducing a new character, object, or event that the reader didn't know of before. That's called a “deus ex machina” intervention and will only annoy your readers. The ending must be internally logical, and complete.

10. Authentic details
To create a believable mystery novel, it is essential to pay attention to details and conduct thorough research. Whether it involves understanding police procedures, using accurate technical terminology, or portraying a specific time period authentically, incorporating accurate information enhances the credibility of the story. Readers appreciate the effort put into crafting a realistic and immersive experience. So don't just guess—do your due diligence and find out what people wore back in the 20s, or how the police go about things, or whether the cause of death is realistic and credible. Accuracy creates authenticity which leads to credibility and helps readers believe the story as it unfolds.