Unwritten rule of whodunnits

March 27, 2019 1:00 AM

I heard ages ago a "rule" that good (or stereotypical) mysteries and crime stories always introduce the killer in the first 1/3 of the plot, otherwise the reveal is cheapened for the audience. Is this actually a written rule somewhere?

I always jokingly apply this to fictional crime shows, where "It can't be [that guy], he just showed up and we're almost done!" This usually helps narrow the suspect.

tl;dr just wondering if there is more to this idea than a one-off fact from years past, whether an author said it, or it has a TV Tropes page, etc.

posted by lesser weasel to Society & Culture (4 answers total)

Ronald Knox set out a ten rules of detective fiction during the golden age of detective novels (although he didn’t always follow them himself) and rule number one is:

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.

There is a good episode about them on the shedunnit Podcast.
posted by halcyonday at 1:40 AM on March 27, 2019

S.S. Van Dine's 20 Rules for writing detective fiction is less prescriptive.

10. The culprit must turn out to be a person who has played a more or less prominent part in the story — that is, a person with whom the reader is familiar and in whom he takes an interest.

And Raymond Chandler, even more so.

For pulp fiction, things are a little less leisurely.
The Lester Dent Pulp Paper Master Fiction Plot:

First 1500 words
3--Introduce ALL the other characters as soon as possible. Bring them on in action.

posted by zamboni at 2:40 AM on March 27, 2019

TV Tropes: Fair-Play Whodunnit, The Law of Conservation of Detail, Only One Plausible Suspect, and Chekhov's Gunman.

Inverted: The Dog Was the Mastermind, Stranger Behind the Mask.
posted by zamboni at 2:56 AM on March 27, 2019

Exactly what I was looking for, thanks all!
posted by lesser weasel at 4:06 PM on March 28, 2019