Whodunit
Quick answer: A whodunit is a mystery built around the puzzle of the culprit's identity, with clues the reader can follow. Learn the fair play rules and how to plot one.
A whodunit is a mystery story organised around a single question, who committed the crime, with the answer withheld until the end and the clues to it planted fairly along the way. In other words, it is a puzzle the reader is invited to solve in competition with the detective. The name is simply the question said fast, and it entered print in the 1930s as slang for the detective novels then flooding the market.
The form dominates crime fiction's classic wing: Golden Age novels, village mysteries, locked rooms, and their thriving modern descendants on screen and shelf. It matters at the plotting stage above all, because a whodunit is engineered backwards from its solution in a way almost no other kind of story is.
The puzzle at work: Poe's blueprint and Christie's masterstroke
Edgar Allan Poe built the machine in 'The Murders in the Rue Morgue' (1841): an impossible crime, a brilliant amateur, a baffled official force, a narrator companion recording it all, and a solution that reorganises every strange detail into sense. Nearly every whodunit since runs on some arrangement of those parts. What Poe understood first is that the form's pleasure is retrospective: the ending must make the reader want to reread the beginning.
Agatha Christie's 'The Murder of Roger Ackroyd' (1926) shows how much room for genius the rigid form leaves. Christie obeys every rule of clueing, then places the guilt where the conventions themselves taught readers never to look. The outrage and delight it caused made her name, and the debate it sparked, was the trick fair or foul, produced the era's formal codes: Ronald Knox's Decalogue and the Detection Club oath, which required that authors hide nothing vital from the reader. Fair play stopped being etiquette and became the genre's constitution.
Why the form endures, and its occupational hazards
The whodunit survives every change of fashion because it flatters the reader with real work to do. It offers the deep comfort of order restored, a disturbance, an investigation, a truth, while smuggling in social observation, since investigating a murder means opening every character's private life. Writers love it for the discipline: nothing teaches plotting like a form where every scene must simultaneously advance, conceal, and play fair.
The hazards are well documented. Characters can shrink into suspects, mere holders of alibis, which is why the great practitioners spend as much craft on grief and motive as on timetables. Clueing can tip either way: too transparent and the ending lands flat, too obscure and the reader feels cheated. And the corpse can become furniture. The modern whodunits that rise above the puzzle, and the contest entries that score across a full rubric rather than on structure alone, are those where the solution reveals something true about people, not just about opportunity and railway timetables.
Plotting a whodunit short story
Work backwards. Decide the culprit, the motive, and the method first, then design the surface story that hides them. Give every suspect a secret worth lying about, because innocent lies are the engine of misdirection: readers chase characters who behave guiltily for reasons unrelated to the murder. Plant each real clue twice, once where it can be seen and once where its meaning shows, and hide it in the paragraph's least emphatic position, mid-sentence, mid-list, while attention is aimed elsewhere.
At short story length, ruthlessly limit the cast: three or four suspects is plenty, one detective figure, one crime. The trap to avoid is the withheld-information ending, where the detective produces knowledge the reader never had. That is not a twist; it is a broken promise, and mystery readers do not forgive it. Before submitting, reread as a sceptic and confirm that a careful reader could name the culprit from evidence on the page.
Whodunit, howdunit, and thriller
The whodunit's neighbours are named by their questions. A howdunit reveals the culprit early and makes method the puzzle, the locked room tradition at its purest. A whydunit, or inverted mystery, shows the crime and criminal at once and drives on psychology, as the Columbo format does. The thriller abandons the puzzle altogether: its engine is danger ahead rather than truth behind, and its question is not who did it but whether the protagonist survives what is coming.
Cosy and noir, meanwhile, are temperatures rather than structures: a cosy whodunit softens the violence and warms the community, a noir one lets the solution redeem nothing. You can set the same puzzle at either temperature.
What poets can take from this
- Plot backwards from culprit, motive, and method before writing a single scene.
- Give every suspect a non-murderous secret to lie about; innocent guilt is your misdirection.
- Plant each decisive clue in plain sight but in the sentence's least emphatic spot.
- Never let the detective solve with facts the reader was denied.
- Reread the finished draft as a sceptic and check the puzzle is solvable from the page.
Try it yourself
Write a whodunit set during a power cut at a small family restaurant: when the lights return, the safe is empty and one of the six people inside is lying. Give every character a secret, plant three fair clues, and let a waiter, not a detective, work out the truth.
Questions
What does fair play mean in a whodunit?
It is the genre's core contract: every clue the detective uses must be available to the reader before the solution. The principle was codified in the 1920s by Ronald Knox's Decalogue and the Detection Club, and readers still judge mysteries by it.
Can a short story work as a whodunit?
Yes, and the form has a rich short tradition from Poe onward. The key adjustments are a small cast, a single crime, and clueing compressed so the solution can land within a few thousand words.
By the Writory editorial team, reviewed by working poets. Updated July 2026.
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