People will talk all about plot and structure, to the point of having you believe that if you made a graph of all of your plot points, it would always match the rising orgasmic curve. Or a three-act structure. Or the hero's journey. Or whatever. All books, people would have you believe, revolve around a central choice your character must make, and without this dilemma there can be no story.
Except none of that is really true. All stories can't be told using The Hero's Journey. Not all stories are epics. And not all stories should be epics.
Here's the thing about The Hero's Journey. I love it, too. I think Joseph Campbell was onto something. But he didn't come up with it as plotting advice for screenwriters -- he created it as an analytical tool to look at the understory behind famous myths. Then you get people like George Lucas who say to themselves, "I bet I can make my film an instant classic by structuring it as much like an epic legend as possible," and it works and suddenly everything takes off.
Some stories clearly follow the Hero's Journey. Star Wars IV: A New Hope. The Matrix. Lord of the Rings. All really excellent classic tales. But not the only storytelling structure out there. Here's some other structures that are just as classic and just as valuable and totally break the mold:
- The siege story. A favorite of samurai movies and Westerns. You've got a big, impossibly powerful corrupt evil force on one side, and the only thing standing in the way of their path of destruction is a tower, bridge, castle, whatever. In order to protect that area and hold it off, the plucky hero must assemble his band of misfits and tired old warriors to stand and fight, knowing perfectly well that they may not last the night but they have to try it anyway. Sometimes a siege is part of a greater story arc (like The Two Towers) but sometimes it's the whole story. For example, The Magnificent Seven, Seven Samurai, 13 Assassins, Ironclad. I'd also go so far as to say that, in their hearts, a lot of zombie apocalypse tales are ultimately siege stories.
- The Greek tragedy. Greeks had really specific definitions about art, and their definition of tragedy wasn't just "something really sad." In order to be a Greek tragedy, you have to start off with a noble hero whose hubris (even well-intentioned) puts him at odds with his fate and he loses everything. These aren't as popular these days, mainly because the downer ending doesn't play well with modern audiences. I would argue that the Star Wars I - III are a Greek tragedy trajectory -- the downfall of brilliant Anakin Skywalker. You could also make a good argument for Scarface, Requiem for a Dream and Chronicle, to name a few. (There's Shakesperean tragedies, too, but people tend to be very overt about their homages to Shakespeare so it's less likely that you'll come across one without automatically recognizing it).
- The Ensemble plot. Known also as a polyphonic plot. You have a large group of protagonists, all of whom shoulder fairly equal weight in a story. One or two may be "true heroes," but they might not be. Everyone is connected by a single central event, setting or time period, and their lives and stories weave together to form a cohesive whole -- even though they generally don't know about each other and their lives make sense in the greater structure only to us, the reader/viewer. For example, the movie Crash. Or one of my all-time favorite films, Magnolia. I'd also argue that this is the primary format of a disaster film, although those often have a person who's ostensibly the "hero" (probably to make the film more high-concept).
- The backwards, sideways, convoluted plot. Stories that start at the end and work their way backwards, or which circle around on themselves to re-tell the same story from different perspectives. These often employ an unreliable narrator, and part of what makes the story compelling is figuring out what you can trust. The classic example is of course Memento. Chuck Palahniuk's book Survivor is told in the same way. Also, notably, Rashomon and all of its many homages.
My point in all the rambling is this: If your story doesn't perfectly fit Joseph Campbell's mold, that's OK. your story doesn't need to follow the same structure as everyone else's story. If there's no room in the market for books that tell good stories in interesting ways, then shame on the market.
And if you're in the unhappy position of trying to write a compelling query letter for a non-traditional plotline, my heart goes out to you. You're fighting an up-hill battle. But it's worth it. That's my promise to you: If the story is good, it's worth it. And some day, the right person will see it and realize that and your hard work will pay off.