Mysteries are one of the most difficult types of narratives to tell well, for a simple reason: their narrative structure - which forces the storyteller to invest an enormous amount of the work's merit on the final reveal - easily sets itself up for failure, because the narrative, as found in real life, is anything but satisfying to an audience (typically).
What do I mean by this? Let's say you have a murder mystery that the police are working to solve; after some time, they determine that the murderer was person X. Unless there's a particularly strong twist (the murderer was someone hiding in plain sight all along!), which is rather uncommon, the reveal of the murderer's identity is not going to be narratively satisfying because it doesn't relate to anything that came before. Typically, we learn that person X is some individual whom we've never heard of before (in a real life murder case as reported in the newspaper), which does not hold a compelling narrative structure. So a movie that presents a murder mystery has to do much more than realistically represent a murder mystery as it occurs in real life; it has to take a murder mystery and give it an ending that relates to what has come before, unlike what typically happens in reality.
I've seen far too many movies that present a cast of characters who may be the murderer, and then, indeed, reveal that it was option B or option F.
Yet many films fail to address this sticking point of the murder mystery structure in an effective way; I've seen far too many movies that present a cast of characters who may be the murderer, and then, indeed, reveal that it was option B or option F. The audience knows that one of these characters will indeed be the murderer and so A) there's not a ton of surprise and therefore B) there isn't much narrative satisfaction derived from the reveal for the audience. And since murder mysteries typically revolve around one question - what is the identity of the murderer? - to fail on this count to be satisfying is to fail with the telling of the whole film. A disproportionately high amount of the film's merit rests on nailing this reveal; as I said, murder mysteries are hard to do.
So I was really impressed by Jane Campion's Top of the Lake, a recent miniseries she made in New Zealand which played on the Sundance Channel last year. Campion is part of the recent exodus of artistic filmmakers from cinema to TV, but she's lost none of her skill as a filmmaker - the miniseries is filled with eerie, atmospheric photography and deliberate pacing that feels far more like a film than a typical TV show.
Revolving around a detective from Australia (Elisabeth Moss) who returns to the small town in New Zealand she grew up in to help solve the case of a missing 12-year-old pregnant girl, the miniseries displays an impressive understanding of the cardinal rule of making a mystery work: eventually, the source of the mystery has to bear back on the individual trying to solve it. The classic example of this is Oedipus The King: Oedipus spends the entire play trying to figure out who has brought this horrific plague to Thebes, only to find out that he's been the evildoer all along. This is a truly satisfying ending to a mystery, since the ending bears upon all that has come before, rather than revealing a truth that is only tangentially related to what we've been seeing, and therefore one that's not all that satisfying. The same is the case with Top of the Lake; there's a satisfying answer to the mystery, but Campion understands that in order to make her story truly satisfying, she has to eventually turn the flashlight around and have her detective examine not only the mystery, but her own identity.
This model, done so effectively in the aforementioned works, is also part of what makes Anthony Schaffer's The Wicker Man such a chillingly brilliant thriller. (SPOILERS AHEAD!) The entire film features Schaffer's detective investigating the disappearance - and potential sacrificial murder - of a young girl on an island of pagan cultists. As Schaffer spends more time investigating, he realizes that the girl is, in fact, alive - and it is he who is to be sacrificed, since he's an outsider who they managed to lure to the island. It's this narrative turn that, time and time again, makes mysteries satisfying - otherwise, their reveals are all too insignificant.