I love mysteries. I love the thrill of uncovering new clues, of guessing who the murderer is, of being wrong, of being right. I love the thrill of seeing the pieces come together in the end. I love a dramatic climax and a satisfying resolution.

Another reason I love mysteries is because it’s easy to break the plot into distinct parts and tell whether or not it’s working. The plot of a mystery is usually more clear cut to me than the plot in women’s fiction or historical fiction.

Whether you’re writing a cozy, a police procedural or something in between, there are certain things a reader expects to see in a commercial mystery. (If your mystery is more on the literary side, then you might not have all of these qualities, but you should have some of them.) Here are the things that keep me turning the pages:

1. There needs to be a murder.Maybe this seems obvious, but I mention it because occasionally I’ll receive mystery submissions where the crime is a heist or drug deal. Books like that fall more in the category of crime than mystery, in my opinion. And for me personally, theft and drug trafficking aren’t as interesting as good, old-fashioned murder, so they’re not likely to inspire me to read more.

There is always the question of when the murder needs to happen in the book. I’ve heard several editors say that they want the body to be found within the first three chapters, so that is a good standard to go by. (But there are always exceptions to that rule. My fabulous client, Libby Klein, holds off on the body dump until the end of the first act, which is often 90 pages in.)

2. There needs to be a reason for the protagonist to investigate.In a police procedural, it’s the cop’s job to investigate, so this reason is obvious. Same with private investigators. Their reason is that someone hired them to investigate.

With an amateur sleuth, the most common reason I see is that the protagonist is the prime suspect. This is a great reason, because there are major consequences for the protagonist if she doesn’t investigate, like going to jail for a crime she didn’t commit. It’s also a great motivation when the prime suspect is someone close to the protagonist (like a family member or friend). Or when the murder has hurt the protagonist’s business in some way, and solving the crime will fix it. For example, a body is found on the protagonist’s vineyard, which keeps tourists away and now she’s struggling to make ends meet.

I’ve received amateur sleuth mysteries where the protagonist decides to investigate just for fun, and they usually stagnate at a certain point. Why? Because there are no stakes for the protagonist. If she doesn’t solve the crime, or if she solves it slowly, nothing bad will happen to her. There’s no fire under her that compels her to solve it in a timely manner, so I’m not desperately turning the pages to find out if she succeeds. It’s easy to root for someone when they have a definable goal, like not going to jail or saving their business from bankruptcy. But when they have a vague goal, like having fun, I don’t know when they’ve reached it. (I mean, they had fun when they impersonated plumbers to get inside a suspect’s house, but was that the most fun they can possibly have solving the case? I don’t know!) So always make sure there is a solid reason for your protagonist to solve the crime and stakes if they don’t succeed.

3. There need to be clues.The purpose of a clue is to point the investigation in a direction, to provoke a question that needs to be answered. A clue can be a million different things. It can be a piece of forensic evidence found at the scene. It can be an eyewitness testimony. It can be a photograph. It can be an anonymous call. Some of these clues will be resolved part way through the book, and some won’t come together until the end. Whatever clues you use, you need to keep them coming if you want readers to keep turning the pages. You want to keep a question in your reader’s mind at all times.

I’ve received submissions where the clues lead to dead ends quickly and new clues aren’t brought in to guide the reader in a new direction. This again causes the investigation to stagnate and lose momentum. So make sure there’s always something left unexplored until you reach the climax.

4. There needs to be building action and tension.One form of building action is the development of clues that I just described. Another is some outside pressure that makes the protagonist need to solve the crime even faster. For example, pressure from his boss that he’ll lose his job if he doesn’t solve it, or pressure from the police that his aunt is about to be arrested, or pressure from the murderer, like an attempt on the protagonist’s life. In other words, the stakes that your protagonist already has have to get even stakier to build up to a climax.

5. There needs to be surprise.This means holding off on revealing who the killer is until the last minute. When you give away this information too early, you’ve created one more reason why the reader doesn’t feel compelled to finish the book. Misdirecting the reader with other suspects is a great way to keep the true killer a surprise.

6. There needs to be showdown between the protagonist and the killer.The protagonist needs to be the one to find and confront the killer. And it’s best if your protagonist does this alone. Why? Because the most satisfying form of climax in a mystery involves your protagonist being in danger, and what could be more dangerous than a one-on-one with the murderer who’s been terrorizing the characters in the book.

This also reinforces your protagonist’s role as the primary driver of action in the story. If your protagonist found the killer and then sent someone else in to make the arrest, your protagonist would come off as passive. For the book to be satisfying, your protagonist has to act to bring about a change in a plot. He has to be the one to wrestle the killer to the ground or to talk him off the ledge. He has to be the only one who knows where the killer is, or has the right skills to bring him to justice, or the only person who put the puzzle together.

Does your mystery have all these things? If it does, congratulations, your book might be ready to send out. If it doesn’t, take a close look at your plot and ask yourself what you can do to build up that area. There is no one-size-fits-all rule for how to write a mystery, but hopefully this will give you a framework to break down the mechanics of your plot to see if it’s running smoothly.