20 Mystery Story Ideas

What makes a mystery such a compelling type of story? Maybe it’s the puzzle, the details that keep us guessing, or the quirky sleuth or investigator. If you love to read mysteries, too, why not give on of these mystery prompts a try today?

As a genre, mystery begins with a crime, a puzzle, or other situation that requires solving. Authors leave clues and red herrings that the sleuth (and reader!) follow to solve the case.

Need help with a structure to get you started? Take a look at our article on the ten types of stories here.

20 Crime Solving Story Ideas

1. Charles McDougall, Scotland Yard’s best Inspector, is laid up in the hospital with a badly broken leg, but that doesn’t mean he’s off the clock! An online news headline describing a tragic gas leak/explosion catches his eye. Four people died: a housewife, a minor politician, a young chemist, and the daughter of a local mobster. Somehow, using only clues from the internet (and what he can worm out of his coworkers), he has to figure out which of those people was the actual target, and why.
2. Agatha Christoph (get it?) is a retired schoolteacher in a beautiful little town in New England. She never married and has no children, so her friends are everything to her. That’s why when her best friend, Martha, is blackmailed with vague threats about some risqué photos from Martha’s youth, Agatha jumps to the rescue. But Martha’s youth was a LONG time ago. Who could have those photos? And what could they possibly want?
3. Mars is colonized, though there’s no air outside the domes. Travel from dome to dome is by train. The Eberswalde Express is the “luxury” locomotive, filled with old-timey elegance and charm. It takes a day and a half between stops to give wealthy patrons full time to enjoy the amenities. AND WOULDN’T YOU KNOW IT…THERE’S A MURDER! Weirdly, this murder mimics the plotline of The Orient Express, and Elsa, a librarian and mystery buff, recognizes the details. With a murderer on board and nowhere to go, everyone is in danger. Can Elsa solve this murder before the killer strikes again?
4. Ever heard the phrase, “It is not who fired the shot but who paid for the bullet”? This is a philosophy Tomoe Gozen lives by. Tomoe (who, by the way, was a real female Samurai) serves her general well, but when a fellow soldier dies mysteriously one night after a game of Chō-Han, she can’t simply accept that the death had no meaning. Brave and clever, Tomoe follows clues until she learns who ordered the murder: Emperor Antoku himself. But why would the emperor of Japan want to kill a lowly soldier? And why the subterfuge?
5. Medieval France. Fourteen-year-old Amée is a servant girl with a genius IQ stuck as a scullery maid in her fief lord’s castle. She leads a lonely life, with plenty of time to think and analyze, though—and this is important—she can’t read. But something strange is happening here. The fief lord keeps bringing new brides home… and within two weeks, those brides disappear. A new one—nearly Amée’s age—has just been brought to the castle, and Amée knows the clock for survival has already begun to tick. She has time to figure this out. Will she before it’s too late?
6. Omar Yehia is a colonel in Cairo’s police department. The government is unstable, and the people are unhappy; he has his hands full with violent cases all the time. Unfortunately, one day, a slain prostitute turns out to have something on her person that no one in Egypt should have at all: Queen Mary’s Crown. How on earth did she get that? More importantly, what will Omar do with the 48 hours his superiors give him to crack this case before they report this to foreign authorities?
7. Sandra is a mystery-lover. She sees mysteries and hidden conspiracies everywhere they aren’t, and her sister Carrie laughs this off as a silly quirk… until Carrie is framed for the murder of the man in the next apartment. Carrie’s DNA is somehow all over the place, though she swears she’s never even been in that apartment before. No one thinks Carrie is innocent but Sandra… and she has a limited amount of time to prove her sister is innocent.
8. Twelve-year-old Alexandra is a leader. She runs her school’s newspaper, manages three after-school clubs (the book club, the fencing club, and the junior stamp-collector club), and doesn’t have time for nonsense. Which is why when she sees a man dressed all in black carrying a manilla folder as he climbs out of her principal’s window, her determination to get to the bottom of it knows no bounds. Look out, data-thief. Here comes Alexandra!
9. David is a senior software engineer for a major tech company, and he spends most days knee-deep in other people’s databases, trying to figure out what they did wrong.  One day, he happens across a piece of malicious code designed to steal financial information. He reports it and deletes it, but he comes across that same code again—in the database of a completely different company. He finds it again; and again. And the fifth time around, his manager drops a hint that the higher-ups think he’s the best person to figure out who’s planting it. Undercover, they send him to each of the company’s data centers: one in London, one in Boston, one in Dallas, and one in Seattle. It’s going to be his job—socially anxious as he is—to interview everyone and find out who’s planting that code and why.
10. General March hires Detective Thomas to try to find the person who’s been blackmailing March for the past twenty years. Thomas tracks the miscreant down, but finds that the man behind the threats has been dead for the past ten years. So who’s carrying on the blackmailing? And is the secret that’s held March prisoner this long something that should stay a secret?

10 More Mystery Story Ideas

11. Defense attorney Bob Larson enjoys his job. He likes justice; he likes being right. Usually, he thinks right and wrong are really easy to spot. Then he ends up representing a young Navy Seal who shot and killed an elderly woman—and claims it was in self-defense. Who’s really the bad guy?
12. Samuel sleepwalks. He also thinks he loves another man’s wife. He’s more surprised than anyone when he’s arrested for that man’s murder. Did he do it? Or is he being set up to take the fall?
13. Mystery writer Dan Rodriguez takes the subway every day. Every day, nothing happens. He wears earbuds and a hoodie; he’s ignored, and he ignores. Then one evening, on his way home from a stressful meeting with his publisher, Dan is startled out of his funk when a frantic Middle-Eastern man knocks him over at a dead run, then races up the stairs—pursued by several other mysterious looking thugs. The Middle-Eastern man is shot; and Dan discovers a small, wrapped package in the front pocket of his hoodie. What’s inside, and what does he need to do to survive the answer?
14. Wealthy, unmarried Anne Lamont is murdered, and she leaves her entire fortune to a man she met two weeks before, putting suspicion squarely on him. Detective Arnold thinks the man is innocent. He has a week to make his case before this goes before a jury. But when he digs into Anne’s background, he finds the sweet old matron wasn’t at all what she seemed.
15. A headless corpse is found in a freshly-dug grave in Arkansas. The local police chief, Arley Socket, has never had to deal with more than missing gas cans and treed cats. His exploration of this weird murder digs up a mystery older than the 100-year-old town of Jericho that harkens all the way back to a European blood-feud.
16. Someone is murdering homeless people in Phoenix, Arizona. Detective Sally Fortnight is determined to get to the bottom of it… but what she uncovers may be more deadly than she could ever guess.
17. On the Lovely Lady riverboat in 1900’s Louisiana, professional gambler Lacroix is just doing his thing when a scream startles him and the other players from the  poker table. It turns out the captain of the steamboat has been murdered, and only someone on the boat could’ve pulled it off. Lacroix already has a record. In two days, the Lady will pull into Shreveport, where he stands a good chance of being arrested… unless he can suss out the killer first.
18. Detective Donna Madison is on a completely routine case (bootleg watches, just so you know) when she stumbles across a ring of jewel thieves. Two murders, a clever fortune-teller, and a stuffed cat filled with clues later, and Donna finds herself uncovering a far bigger mystery than where stolen watches go.
19. It is the Cold War era. Private Eye Charles Nick searches for a missing cryptanalyst, all the while dodging an obsessed FBI agent who thinks Nick is a communist spy. The cryptanalyst, by the way, went missing for a good reason: he might have cracked the latest Russian spy code, and he’s running for his life.
20. 1850’s England: elderly Doris and her six young wards are caught in a storm and forced to ask for shelter at an enormous manor deep in the English countryside. But all is not well in this home, and before long, Doris faces a bizarre problem: the manor’s lord, Sir Geoffrey, claims his estranged wife Alice is going to murder him that evening. Alice, meanwhile, claims that Geoffrey is going to murder her. After dinner, both are found dead, in the library, seated as if having a rational discussion, but dead as mice. There is no obvious murder weapon, and quite possibly, the murderer is loose in the manor. Doris is no detective, but she might as well figure this out. Given that storm, help won’t be coming until it’s too late.

(This is the fourth in my series of story ideas, by the way.  If you’re interested in the others, check out 20 fantasy story ideas, 20 sci-fi story ideas, and 20 romance story ideas.)

Do any of these story ideas get your inner-criminal devising? Let us know in the comments.

Best-Selling author Ruthanne Reid has led a convention panel on world-building, taught courses on plot and character development, and was keynote speaker for The Write Practice 2021 Spring Retreat.

Author of two series with five books and fifty short stories, Ruthanne has lived in her head since childhood, when she wrote her first story about a pony princess and a genocidal snake-kingdom, using up her mom’s red typewriter ribbon.

When she isn’t reading, writing, or reading about writing, Ruthanne enjoys old cartoons with her husband and two cats, and dreams of living on an island beach far, far away.

P.S. Red is still her favorite color.