Fair Play Whodunnit

""Do you promise that your detectives shall well and truly detect the crimes presented to them using those wits which it may please you to bestow upon them and not placing reliance on nor making use of Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence, or Act of God?""

- G. K. Chesterton's oath for membership for the British Detective Club.

The opposite of a Clueless Mystery; the puzzle of the story is entirely solvable before The Reveal or The Summation, if you've spotted the clues, and not just by various methods of being a Genre Savvy reader/viewer.

In 1928, the writer Father Ronald Knox created a "Ten Commandments" of plot devices that more or less codified the rules of the Fair-play whodunnit:


 * 1. The criminal must be someone mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to follow.
 * 2. All supernatural or preternatural agencies are ruled out as a matter of course.
 * Some modern interpretations allow violation of this rule if the Magic A Is Magic A rules are strict enough and Rule 4 is followed.
 * 3. Not more than one secret room or passage is allowable, and such a passage may only be in a house or building for which it is appropriate by age or purpose.
 * 4. No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.
 * 5. No Chinaman must figure in the story.
 * Note that this was not a case of racism (though the now-offensive but generally obsolete term "Chinaman" is a case of Values Dissonance), but a reaction against the clichéd Yellow Peril villains prevalent in dodgy crime fiction at the time. The modern American equivalent would also include a Middle Eastern character or a Scary Black Man, or anyone known to have enough acting ability to pull off the role.
 * 6. No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.
 * 7. The detective must not himself commit the crime.
 * 8. The detective must not light on any clues which are not instantly produced for the inspection of the reader.
 * 9. The stupid friend of the detective, the "Watson", must not conceal any thoughts which pass through his mind; his intelligence must be slightly, but very slightly, below that of the average reader.
 * 10. Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.

Other such lists can be found here.

Though increasingly rare in modern mystery literature (and in any media outside of print), in the "Golden Age" of mystery, novels were almost entirely of this type (though even then, some were better about the "fair" part than others).

Done badly, this can lead to Conviction by Contradiction. Done correctly, and it turns into what Golden Age writer John Dickson Carr called "The Grandest Game in the World."

Anime and Manga

 * Two manga, The Kindaichi Case Files and Case Closed, based upon teenagers solving mysteries, give you the information to unveil the killer before the solution is officially "revealed" - Kindaichi much more so, because the translators go through more effort to translate the evidence to English, while to solve the Detective Conan mysteries, once in a while you'll need to know various Japanese references, names, and pronunciations.
 * Unfortunately for Detective Conan, this doesn't translate to the anime, which feels free to hide the evidence from you. (Although, especially early, Funimation made more of an attempt to translate cultural-specific info than Viz does with the manga.)
 * The anime is sometimes good about playing fair, and other times shamelessly cheats. It depends on the writer, though the show seems to cheat more nowadays than they did in earlier seasons. Any story based on the manga will still be fair play, though, unless something crucial is cut during the shift from manga to anime.
 * The Melancholy of Haruhi Suzumiya has the mystery episode "Remote Island Syndrome". The first part of the episode seems to be a regular fun-filled day on a private island. That episode secretly contains almost all the clues you need to solve the mystery presented in the second half, although if you don't expect the mystery, you could easily miss them.
 * However, it's implied by Unreliable Expositor Koizumi that Haruhi, despite noticing the clues, never actually solved the crime—she changed the facts of the case to fit the clues.

Comic Books

 * Mike W. Barr's The Maze Agency series revolved around a beautiful ex-CIA agent who runs a PI firm, her true crime writer fiance, and the (usually fairly clued) mysteries they run across.
 * A number of Batman comics, particularly during the Denny O'Neill/Neal Adams period in the '70s, provided fair-play mysteries. The narration would even challenge the reader at one point, once all the clues were presented to solve the crime before Batman.
 * A slight example: In The Many Deaths of the Batman, Batman seemingly falls off a roof and into a river while chasing a crook, and his body is fished out of Gotham River. Observant readers will note that the first chase sequence clearly has the Eiffel Tower in the background. Sure enough, Batman's alive and well, just a bit damp.
 * Roger Stern's run on Amazing Spider-Man had several hints as to the Hobgoblin's identity, such as that he was wealthy, upper-class, and was someone who was cunning and ruthless. Although it was revealed that the Hobgoblin did have an identical twin who posed as him whenever he was dressed as the Hobgoblin, there was one tiny hint to this in a single panel. So if someone had found this tiny hint, they likely could have worked out the Hobgoblin's identity, although with various changing writers, the whole thing soon became a confusing mess, which was only really fixed when Stern himself returned to write the Hobgoblin Lives! miniseries, over ten years after the Hobgoblin's first appearance.

Film

 * The film The Last of Sheila, where not only is the title a clue, but if you pay close attention during the early scenes you will see a vital clue that directly points to the murderer's identity.
 * Played with in Deep Red; an early scene actually shows the face of the murderer, but it's done so quickly - and before you know to look for it - that most people never catch on.
 * The Japanese film The Laughing Policeman plays with this trope. Many clues are given from the outset, but many are so subtle at first that the detectives don't notice them at all until towards the end. It also subverts this by having someone  offscreen just as the cops plan to arrest him. This is only to reveal the real mastermind, the titular Laughing Policeman.

Literature
"Gregory (Scotland Yard detective): Is there any other point to which you would wish to draw my attention? Holmes: To the curious incident of the dog in the night-time. Gregory: The dog did nothing in the night-time. Holmes: That was the curious incident."
 * Agatha Christie was a member of the Detection Club, the members of which promised to write their stories like this. However, that didn't stop her from having the narrator lead the reader down the garden path to the wrong answer. For example: in "Hercule Poirot's Christmas", Poirot asks the butler what the date was three days ago; the butler walks over to a wall calendar and reads off 'the 22nd'; and the reader is led to conclude that there is something important about the date. However, During The Summation, Poirot says that the whole point was to find out if the butler had bad eyesight. She also plays fast and loose with the  rules, by dropping  into the pot.
 * Several of the Miss Marple short stories were the ultimate in fair play. They were told to Miss Marple by guests at a party, so the reader knows exactly what the detective knows. It also helps explain what an elderly woman is doing solving mysteries.
 * In both The Big Four and The Murder of Roger Ackroyd Christie violates as many of these rules as she can, probably on purpose.
 * The Mysterious Affair at Styles is absolutely a Fair Play Whodunit. The reader knows everything Poirot does. No unknown illegitimate children there.
 * The Murder of Roger Ackroyd is also extremely fair. The way Poirot ultimately solves the crime is by reading what Dr. Sheppard wrote down which is exactly what the reader is reading. Which means that an acute reader could actually pick up most of the important clues before Poirot does.
 * Michael Connelly's mystery novels are often these; The Poet actually won an award for Fair Play.
 * Note: make sure you read this before reading "The Narrows"
 * There's a Lord Peter Wimsey mystery where a particular missing item from a painter's setup is an important clue that the painter had been murdered, rather than died accidentally, and the page revealing what it is before The Summation, in a vaguely clever twist, is removed for "the entertainment of the reader".
 * Sayers still plays fair, though. There are three or four other scenes between the missing page and The Summation which, taken together, can be used to work out what the object was and what happened to it.
 * In fact you can deduce what's missing in the same way that Lord Peter does, from the description of the scene alone, although a (very) basic knowledge of oil painting may be needed.
 * A straighter subversion is Have His Carcase, where the solution requires on a very elaborate trick involving the time of death.  If the reader is knowledgeable enough in minor trivia, there are enough clues for a genius to figure out what the trick is - but it requires a very specialized knowledge base that most people simply do not have. For those without the prerequisite knowledge, Lord Peter's revelation seems a bit like an Ass Pull or Deus Ex Machina, though the astute and Genre Savvy reader can generally figure out that something is hinky, because everyone's alibi is too solid, which is what tips Peter off that something is hinky.
 * Most Sherlock Holmes mysteries are not really fair, if only because Dr. Watson (the narrator) is not as observant as his colleague, but "The Lion's Mane" gives the reader enough information to draw a conclusion even before Holmes does (although this may not have been Conan Doyle's intention).
 * It bears mentioning that Watson is usually writing these up after the fact. He could give the reader the clues—Holmes himself professed a preference for a didactic style of write-up that would be something like this trope—but arguably intentionally averts the trope in order to play up Holmes's brilliance, as well as for the continuity of the narrative. If Watson's powers of observation had been greater, it might be true that his normal narrative flow might well play the trope straight.
 * "The Lion's Mane" was one of the few stories narrated by Holmes himself, which could mean the difference was intentional after all.
 * Silver Blaze is another. All the important clues are shown to the reader, leading to one of the greatest detective fiction quotes ever.


 * All  Encyclopedia Brown mysteries are deliberately like this... but some of the "solutions" are less plausible than others.
 * Isaac Asimov deliberately wrote his Black Widowers mystery stories in this fashion.
 * The Caves of Steel and the other Elijah Baley novels were also written to prove that it was possible to write a Science Fiction Fairplay Whodunnit, despite the risk of violating the Fourth of Knox's Commandments above.
 * Asimov also tweaked the novelization of Fantastic Voyage to provide clues to the identity of the saboteur in the crew, as well as to paper over the scientific problems with the concept.
 * In Shirley Jackson's 'We Have Always Lived in the Castle', an entire family was murdered, and the answer to which of the three survivors committed the crime is fairly clued within.
 * The Nero Wolfe stories by Rex Stout, may or may not be Fair Play, since they're all narrated by Archie Goodwin, Wolfe's dogsbody and legman. Archie reports everything he finds to Wolfe, but Wolfe often doesn't return the favor, leaving both Archie and the readers in the dark. As a result, Archie and the reader usually have about the same chance of solving the mystery. If it is a Fair-play story, Archie will tell the readers at some point that he figured it out, and that they can too.
 * The Ellery Queen novels—the first eight, which contain a nationality in the title, and the ninth, "Halfway House"—were like this, and would actually have a point before the solution where the story would pause and the author would tell the reader that they now have all the facts required to solve the mystery. This "Challenge to the Reader" was carried over to the Ellery Queen radio show and 1970s TV series, where Ellery would make a "Challenge to the Viewer" before the final ad break.
 * Neil Gaiman says that he tried to make Murder Mysteries entirely solvable for acute enough readers—he even made the title a clue (as it implies that ).
 * On the other hand, if you're not an acute reader, you might miss the fact that there were any murders other than the one in Raguel's story, namely that . This is not helped by the fact that even the murderer doesn't remember what he did  . The comic book adaptation by P. Craig Russell makes it slightly more obvious
 * The stories of John Dickson Carr (as well as his pseudonym Carter Dickson) always showed you all the clues. The only problem was usually that the murder was impossible to begin with, so you couldn't figure out how, much less who. Carr even lampshaded the tar out of this in The Three Coffins when Dr. Fell stops in the middle of the novel to explain all the ways you can do a locked room mystery, because there was no point in pretending they weren't in such a novel. At the end of the chapter (yes, it's a full chapter of all the ways to pull one off) the other characters tell him that the two murders don't fit into any of his categories.
 * Carr's essay "The Greatest Game in the World" makes a key point about what makes a Fair Play Whodunnit really fair, and good when done right: the key to the case isn't just one clue - a random word hidden in chapter six - but a system of interlocking clues that allow the reader to open a tapestry of interpretation that gives a larger picture: that of the truth.
 * Scott Turow's Presumed Innocent delicately scatters its clues amidst character development and the trial plotline—all the reader needs is in the text.
 * The Lord Darcy mysteries are an interesting case, in that they violate Rule #2 (since some of the characters have magical powers) and still manage to play fair with the reader. However, since the universe the stories are set in has consistent magical rules, Rule #2 could be said to be broken in letter but not in spirit. In some of the stories the whole point is that everyone assumes an impossible murder was done by magic, and Lord Darcy explains how it could have been committed in a perfectly mundane way. Magic is mostly used for forensics.
 * The Harry Potter books are like this; the mystery plot is deliberately littered with Red Herrings to lead Harry (and the reader, by extension) down the wrong path at first, but an acute reader can pick up on the actual clues and determine the true culprit before Harry does. For example, Harry Potter and The Chamber of Secrets drops several easily-missable clues about being the opener of the Chamber of Secrets, the most notable being  long before it becomes a major plot point.
 * In fact, many readers who had become used to Rowling's extensive use of Chekhov's Gun and Chekhov's Gunman were able to figure out a couple of things the sixth book set up before the seventh book confirmed them: the identity of "R.A.B." and that is a Horcrux.
 * And even smaller ones, like.

Live Action TV

 * Murder, She Wrote actually had quite a few, given that the killers usually revealed themselves by saying something only the killer would know or assume.
 * The occasional Law and Order spin-off (although not the original, for reasons related to its structure) will do this, probably more or less by accident.
 * Law and Order: Criminal Intent does this more often than the others. Excluding the cases where you know who did it from the very beginning about a third of the shows have enough clues to solve it part way though, a couple can almost be deciphered based on the opening.
 * Some episodes of Monk, before they stopped caring about the mystery aspect of the show. In the early seasons, what set Monk apart was his ability to notice important clues and details that other detectives didn't see, and he would then point them out. At that point it was often possible to put them together and solve the case along with Monk.
 * The British game show Who Dunnit! was based upon this concept.
 * Star Trek: Deep Space Nine: Arissa asks Odo if he's worked out who the killer in the book was. He says "by the third page." Either he's just that good or the book's just that bad.
 * Jonathan Creek was well liked among those who enjoy fair play mysteries, since even though the solutions to the various mysteries were always unusual and required lateral thinking, you always got to see everything the heroes saw that allowed them to solve the puzzle, and usually even had them highlight the significance of the clues.
 * The short-lived Scene Of The Crime, hosted by Orson Welles, was an attempt at a series revolving around a different fair-play mystery or two per episode.
 * The Cluedo TV series.
 * The early episodes of The Mentalist.
 * Japanese live action series Furuhata Ninzaburou, in addition to being a Reverse Whodunnit, also provides additional clues to show the viewer how Furuhata ends up on the trail of the suspect. Like the Ellery Queen example, he would pause just before the final act to address the viewer and give them hints as to why he believes that the chief suspect did it, and what evidence there is to force a confession.
 * The episode guest starring baseball player Ichiro goes even further than usual, as Not-Really-Ichiro goes out of his way to leave a clue at the scene because he believes in fair play.
 * Sleuth 101
 * "A Study in Pink" on BBC's Sherlock was fair play for the "who" part if not the "how" and "why." The audience knows what all five victims had in common -  - and they are also aware of at least some of Sherlock's thought processes ("Who do we trust, even though we don't know them? Who passes unnoticed wherever they go? Who hunts in the middle of a crowd?"). Sherlock said that the murderer must have   and when John texts the murderer, a   shows up at the crime scene - Sherlock and John initially assume it must be the , not realizing that it's actually the   Viewers had enough information to figure it out before the climax.
 * The 1975 NBC series Ellery Queen. Better yet, it always had a No Fourth Wall moment every episode, immediately following Ellery's mandatory Eureka Moment, during which he would turn to the audience, briefly review the key evidence for the viewers, and ask them if they'd figured out who the culprit was.
 * This was a trademark of its predecessor radio show as well.

Video Games

 * The two mystery subquests in Knights of the Old Republic play completely fair, given that it's up to you to solve them. (Admittedly, one isn't much of a mystery, though.)
 * There are a lot of Red Herrings to make it look more difficult than it is—especially given the black and white morality of the rest of the game.
 * In the Ace Attorney games, since the focus is entirely on the clues and how they fit together, it is occasionally entirely possible to figure out who the killer is before The Reveal. This is, of course, when the mystery isn't already a Reverse Whodunnit, or Clueless Mystery. The hard part, of course, is proving it.
 * It gets ridiculous in the last case of Ace Attorney Investigations. Edgeworth figures out the culprit easily, but proving exactly what happened and how it was done is such a laborious process that you're given a save point in the middle of the interrogation.
 * The mystery in the second chapter of The Witcher is done fairly, perhaps even generously, giving the player multiple opportunities to gather all clues. The best rewards are for solving it through questioning suspects and studying books before even looking at physical evidence. Failing to solve it leaves the player with reduced experience gains and a disadvantage in the confrontation with the real culprit.
 * Persona 4 counts. The player is given all the information, and the culprit is someone they know. In the endgame, the player is given a list of all the characters (s)he has met so far, and a set of clues which should narrow it down to one person. They must then select the culprit correctly within three guesses, or be foisted off with a bad ending. Unfortunately, there's 80 hours of dungeon crawling between those vital clues and the event when it becomes crucial to remember them.
 * Luckily,
 * The Eagle Eye Mysteries PC game series eventually becomes this for older and more seasoned and experienced players.

Visual Novels

 * Umineko no Naku Koro ni starts out rather questionably if it's a mystery or a fantasy, and it's the main conflict of the first four arcs. By the fifth arc, however, the reader is presented with the Knox's Decalogue as a hint to solving the mysteries presented, and it becomes up to the reader on whether the entire thing was truly fair play. In fact, in Episode 7, a character actually says that the entire thing can be solved by the fourth arc.
 * The veracity of that claim is debated hotly to this day.

Web Original

 * The Big Idea of the Whateley Universe is a Fair Play Whodunnit, even though the superpowers of the characters add complications over the usual detective story. The reader even has more information than Reach, the character who plays the detective in the story.
 * From SCP Foundation, the whole point of SCP-5002's File. SCP-5002 is a mystery writer whose stories somehow become real, but after taken into custody by the Foundation, she herself is the victim - stabbed to death in her cell, the door locked, and no sign of forced entry. Who killed her? How did it happen? Did she actually cause her own death by writing about it? Well, that's the Trope, you figure it out.

Western Animation

 * Lampshaded in the theme song to A Pup Named Scooby-Doo, which was quite a bit more fair than the Clueless Mystery-type escapades of the previous series.
 * A lot of later series became more fair when it came to mysteries, though some would return to the Clueless Mystery route (but they would usually at least try to lampshade it).
 * The first few Sideshow Bob episodes of The Simpsons were this kind of story; later on, the writers abandoned the mystery angle because coming up with them proved too difficult.
 * And of course special mention must go to the 2-part Season 6 closer/Season 7 opener "Who Shot Mr. Burns?". Even though the culprit did seem to come out of the blue, the clues were indeed all there, with the mystery even being drummed up as a contest to see who could figure it out. In fact, the culprit was actually properly identified by a fan of the show, legitimately using the clues presented, in the summer between the two episodes. Sadly, he didn't actually win anything.
 * The writers lampshade this by ending the first part with Dr. Hibbert turning to the viewer and saying "Well, I couldn't possibly solve this mystery...can YOU?" Then the camera pans back and we realize he's actually talking to Chief Wiggum.
 * The reason the fan didn't win was because the contest was so poorly designed. The way it worked was that of all the entries, the producers would choose a thousand, out of which they would pick whoever sent in the correct answer. Unfortunately, from the thousand that they picked, no one actually had the correct answer. You would assume that they would just start again with another thousand, but the rules specifically stated that the winner had to be out of the first thousand picked. So, they just chose someone randomly. Of course, this meant that any number of people could have sent in the correct culprit, just were unlucky to not wind up in the final thousand.
 * Pops up in My Little Pony Friendship Is Magic in the episode "The Mysterious Mare Do Well". There are deliberate clues throughout the episode to Mare Do Well's identity, though it does require some knowledge of the series continuity to puzzle out correctly.
 * The My Little Pony Friendship Is Magic episode "MysteryOnTheFriendshipExpress" kinda follows the rules for the first half (the introduction and crime), but then throws them away and conceals all the clues discovered during the investigation proper.
 * When Pinkie runs down to the caboose,
 * Next, in the engine car,
 * Finally, much easier to spot is after the blinds are shut,
 * The My Little Pony Friendship Is Magic episode "MysteryOnTheFriendshipExpress" kinda follows the rules for the first half (the introduction and crime), but then throws them away and conceals all the clues discovered during the investigation proper.
 * When Pinkie runs down to the caboose,
 * Next, in the engine car,
 * Finally, much easier to spot is after the blinds are shut,