How to Write a Mystery That Keeps Readers Guessing

Warning: spoilers ahead. Especially if you want to learn how to write a mystery.

After all, there is no talking about mysteries without pointing out the twists and turns that beguile us. The unknown is what grips us—we have to know what’s gone wrong. We have to find out what happens to our favorite mystery characters. We have to know their secrets. Most of all, we have to find out how it all ends. It’s no wonder what makes mysteries so engaging for readers. But what if you’re the one writing the darned thing? It’s the easiest thing in the world to eat a piece of cake. But when you’re the one responsible for baking it, a thousand things can go wrong. 

Learn how to write a mystery that keeps readers guessing. You’ll need to start with a recipe—a way to keep people reading. And the first ingredient is...

How to Write a Mystery

“You can’t put it down because the chapters are so short.”

- Roy Kent of TV’s Ted Lasso, explaining why he can’t put down a Dan Brown novel

Okay—ending the introduction with a cliffhanger was a bit of a cheap trick. But it gets to the heart of what makes a page turner so intriguing, and an essential piece of how to write a mystery: You have to keep the reader wanting more. 

Did you see Ted Lasso this season? Then you may remember the typically-grump Roy Kent explaining that he couldn’t put down his Dan Brown novel because the chapters were so short. It hints at an important truth: No matter who your audience is, no one can resist a good mystery. 

But short chapters aren’t really the explanation, are they? You can have a book full of short, dull chapters. That won’t work.

Let’s assume you have the basics, like writing mechanics, down pat. What else can you do to keep your readers hooked? Dan Brown novels do two things relentlessly:

• Tease the audience with just enough information to introduce complexity to the plot, holding our interest
  
• End each chapter just before we find out a deeper or newer secret

If you’re emotionally invested in the story, any hint that you’re about to find out game-changing information is downright addicting. The same is true for any genre of fiction writing, but with mysteries? It’s essential.

Let’s look at some of the specific elements of a mystery you can start incorporating into your work.

What Is a Red Herring?

The red herring is a literary device based on a false premise. If an author can get your attention going one way, they can sneak in other information to build the true twist. An author has an entire book to fill, after all. They can’t give it all away in the first half.

What is a red herring in practice? A famous example of a red herring (and we did warn you that spoilers were coming) comes in Gillian Flynn’s Gone Girl. 

In Gone Girl, we meet Nick, Amy’s husband, and a narrator who seems a little bit skeevy. Not only is his wife missing, but Nick doesn’t seem to give the reader a straight answer as to what happened. We even find out he’s been cheating on Amy. Halfway through the novel, with the cops closing in on him, we’re certain he did it. Until…

Well, suffice it to say, it was a red herring. Nick isn’t a good guy, but he didn’t kill Amy. The second half of the novel details how Amy framed Nick in an attempt to start a new life—and the tension ramps up from there.

Characters

A good whodunit plays with the trustworthiness of any mystery character. Nick Dunne of Gone Girl is a classic example of a main character we can’t quite trust. In Agatha Christie’s classic mansion mystery, And Then There Were None, Tony Marston is portrayed as an untrustworthy young man. We instantly mistrust him. 

Then he’s one of the first to die. 

Instantly, Christie throws the readers off their game. We thought we knew what was going on, but by playing with our expectations of each mystery character, Christie has us completely off-balance. If Tony can go, who’s next?

“Slowly Unpeeling the Onion”

A good mystery is not a single twist. It’s an onion composed of many layers. As the reader finishes one chapter, there should be a sense that they’ve only peeled one layer off. They know some information—enough to keep them interested—but that information should only deepen the central mystery before the final reveal.

Think of one of the most famous cinematic mysteries of all time, The Sixth Sense. It’s famous for its gut-checking twist: Bruce Willis was dead the entire time, one of the many ghosts appearing to Haley Joel Osment’s character.

It’s a unique idea. It’s what the movie is famous for. But then you start to rewind the tape. You see little hints dropped in. Why wasn’t Bruce Willis’ character speaking to other alive people? Slowly unpeeling the onion made the entire ride interesting—and made the final reveal that much more impactful. It’s a successful twist if it can both catch us off guard and make us exclaim: “I should have seen it coming!”

The Elements of Writing Suspense

Most good mysteries are really suspense novels. It may contain a puzzle of a story—this thing we call the mystery—but the actual events of the plot find their root in suspense.

What is suspense? It’s the art of building plots that lend themselves to dramatic tension.

In literary novels, the tension often comes between characters and their desires. The Catcher in the Rye isn’t a suspense novel, but there is a tremendous amount of tension between Holden Caulfield and the world around him.

In suspense novels and mysteries, the tension often comes from the plot as well as the characters. Take Delia Ownes’ Where the Crawdads Sing. Much of the novel has a literary approach to its central character, Kya the “Marsh Girl,” and the swamps of North Carolina. But there’s also an element of suspense: someone in the town has turned up murdered, and Kya Clark is the chief suspect.

While one story traces Kya’s history from childhood to adulthood, a parallel story set years later follows the police officers who are solving the crime. This leads to suspense in the reader. Though we sympathize with Kya the child, did she really grow up to be a murderer? Tense courtroom drama scenes play this mystery out.

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How to Start a Mystery Story

A mystery is essentially a question your story asks. In learning how to write a mystery, you might ask: how do you start asking that question? How do you make it hard for the reader to close the book after reading the first chapter? Get going right off the bat. Every good mystery starts with an effective hook, which is the central question that opens the story. Consider the following:

• And Then There Were None: Strangers are brought together in a mysterious mansion with no explanation as to their connections. Tension and mystery are built into the premise from the start; there’s no dilly-dallying here.
  
• The Big Sleep: Raymond Chandler’s hardboiled crime novel opens with Philip Marlowe on a new case: blackmail. Notice how the plot opens. Rather than getting Marlowe’s background and what he had for breakfast, The Big Sleep starts with Marlowe already arriving at his client’s mansion. The reader won’t have to wait long to hear the central hook.
  
• The Girl With the Dragon Tattoo: In Stieg Larsson’s story, we find out early on that a prominent character receives a mysterious flower for his birthday every single year. What’s happening? We have to keep reading to find out.

Your hook for the book sets the tone. As Kurt Vonnegut often wrote, start as close to the end of the story as possible. When writing mysteries, don’t open the story with 10 years of backstory. Open your book with the chief disturbance that takes our characters out of their element. Readers don’t care about average circumstances; it’s the mysteries we’re after. Get to it as soon as possible.

How to End a Mystery

You’ll have more freedom here. But readers typically expect at least some sort of answer to the central question of the book. If you do that, and reveal your final twist at the climax, you can get away with a lot. Here are a few of your options.

• End it well: A conventional crime mystery might end with a twist—the murderer was the brother, not the sister, or vice versa—and then wrap it up with the bad guy in jail. The private investigator finally gets to take that vacation to the Bahamas. Satisfying, even if it doesn’t necessarily leave us craving more.
  
• End it not-so-well: As long as the reader doesn’t feel short-changed, you can have a satisfying ending in which the good guys don’t win. Take the film Se7en. One final blow to one of the detectives, played by Brad Pitt, ends the entire dark story on an even darker note. But we still learn what’s behind the “seven deadly sins” killings and who the killer is. The viewer didn’t exactly get the happy ending they wanted, but they certainly don’t feel short-changed.
  
• After the climax, hint at future misfortune: In Stephen King’s Mr. Mercedes, the Mercedes killer is ultimately caught and brought to justice. Even so, King ends it on a sour note: the Mercedes killer wakes up from his coma. We’re left wondering if the story is really at its end.

How Long Should a Mystery Novel Be?

A good rule of thumb for all conventional novels is they should be 70,000 to 100,000 words. Any shorter and you run the risk of being a novella. Any longer and you’re getting into “epic fantasy” territory. If you write a tight, solid mystery of about 85,000 words, you’ve probably got a good handle on the length.

This isn’t to say readers will ignore shorter books. Or that they’ll always put down long books. If you can keep your readers’ attention for 300,000 words—as George R.R. Martin routinely does in his epic fantasies—that’s great. But if you’re a first-time author looking to secure the attention of a literary agent, anything longer than 110,000 words for a mystery is going to set off alarm bells. 

What Are the Types of Mystery Novels?

The major types of mystery novels often overlap with each other. But ultimately, you’ll find mysteries tend to fall in one of these categories:

Crime Mysteries

A classic mystery—someone has gone missing or turned up murdered, and it’s up to our protagonist to figure out why. This also overlaps with hardboiled novels like The Big Sleep, or novels with true crime elements.

Cozy Mysteries

This is a broad category that minimizes violence and trauma and sticks to the fun of figuring out a puzzling story. A recent bestseller, When We Believed in Mermaids, keeps violence to a minimum and focuses on a protagonist's search for a long-lost sister. This category overlaps with more light-hearted detective stories, such as the Sherlock Holmes mysteries.

Legal Thrillers

Here the focus is usually on a protagonist like a lawyer. This puts the readers in the shoes of someone who’s coming to a situation just as blind as we are. Joseph Finder’s High Crimes is an example of a legal thriller with a unique niche: a military court-martial. 

Police Procedurals

Not quite legal thrillers, police procedurals shift the focus to on-the-ground details of the mystery. Where the Crawdads Sing artfully combined a police procedural with a parallel coming-of-age story.

Famous Mystery Writers

Want to brush up on your mystery writing by learning from the greats? Here are a few famous mystery writers.

Agatha Christie

Maybe the biggest mystery author of all time. Agatha Christie’s books like Murder on the Orient Express practically invented the genre.

Stephen King

Though he switches genres from horror to suspense to science fiction and everything in between, Stephen King is a master of modern mysteries. Even King’s stories in other genres will have mysterious elements in them, such as 2009’s Under the Dome. Where did this giant glass dome come from, anyway?

Gillian Flynn

Gone Girl cemented Gillian Flynn as a modern mystery whiz, but don’t forget about novels like Sharp Objects, in which the protagonist, a reporter, has to solve the mystery of a serial killer loose in her hometown.

Dan Brown

Brown’s mega-popular novels are often mysteries centered around treasure hunts, lost artifacts, and historical mysteries. His famous mystery thriller, The Da Vinci Code, sold tens of millions of copies within a few years.

Get Your Readers on the Edge of Their Seats

To succeed in figuring out how to write a mystery, you need two elements: something to care about and a puzzle to solve. If you don’t care about it, you’ll put the book down. If there’s no puzzle to solve, it’s not a mystery.

From there, you’re free to play with the form. Sometimes, authors can put their protagonists in situations where both elements play out the same way. In Stephen King’s Misery, we sympathize with the author protagonist who doesn’t know where he’s woken up; only that he’s been in a terrible car accident and, like him, we know we would want to get out of Annie Wilkes’ house right away.

To keep your readers on the edge, remember that a good mystery is just as much about compelling questions as it is the answers. Think of your story as more than a single arc. Don’t just write a mystery novel; give your readers a puzzle to solve. Then realize that in a mystery novel, it’s just as much about the journey as it is the destination.

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