So you want to have a mystery show? Well, there are only a few kinds of mystery, truth be told:
* A pure procedural, usually [[PoliceProcedural police]] based: We know what the viewpoint characters know. Favorite lurking grounds of YourPrincessIsInAnotherCastle.
* The FairPlayWhodunnit: You know what the Master Detective knows, and if you're smart enough, at a certain point, you can solve it ahead of him without being Genre Savvy.
* The CluelessMystery: Not really a mystery, but shows up in mystery shows anyway. Sometimes a sign of poor writing, although sometimes it's the point of the story in question.
* The ReverseWhodunnit: Not a mystery per se, but shows up fairly frequently; also known as "Columbo-style" and a Howcatchem. When done poorly, it becomes a ConvictionByContradiction.
* Owen Johnson's "One hundred in the Dark" doesn't fall into any of the above. The narrator mentions the various types of mysteries, then offers his own original mystery that fulfills what he says are the obligations of a story. [[spoiler:A priceless necklace is stolen at a dinner party. The enterprising victim, who also happens to be the hostess, comes up with a solution that manages to get her stolen property back. However, the result is that the mystery of who took it in the first place [[TheUnreveal will never be solved.]]]]
Consult [[http://www.diogenes-club.com/knoxrules.htm Father Knox's Ten Commandments]] for some additional insight into how classic mysteries are to be written.