Say the word "plot" in a graduate-level creative writing course and it's likely it will be greeted with derision. The inverted checkmark is infamous and widely reviled, but it is useful. If you haven't heard of it before, here it is, in all its villainous glory:
Exposition: This is the introduction. It's where the story gives enough information about the characters and situation that readers aren't lost. It lets us know who these people are, what they do, what their problem is, what's about to go wrong in their lives, and why we should care in the first place.
Rising action: This is where things start to fall apart. Shit gets real. Dead ends and frustration abound. Protagonists find out all is not as it seems, and are often their own worst enemies. Character flaws are revealed, friendships fall apart. And the original problem still isn't even close to being solved.
Climax: This is 'it.' After struggling through everything that fate can throw at them, protagonists come to the crux of the matter, and either succeed or fail. Everything in the story builds to this.
Falling Action: Even after the problem has been fixed (or not), it's still not over. People's lives have been ruined. Explosions may still happen. The hero has to escape from a crumbling fortress in the style of Japanese RPGs. Solving the problem doesn't mean the work is done.
Resolution: Now that all the loose ends have been taken care of, if this story was a meaningful one, the protagonist is in a much different situation and is a different person because of the adventure. In the resolution, the story lets you know what this new normal is.
Mustache and Monocle: Proof of elegance and refinement that cannot be tarnished by the calumny of knaves.
It's not that easy to turn Mr. Plot, Esq. into a story, so let's outline a sample plot. First, we need a who. Let's call him Randal Marks.
What does Randal do?
He's a district sales manager for a document company.
What's his problem?
He owes money to a bookie.
What's about to go wrong with his life?
In order to pay his debts, he needs a promotion. This promotion is riding on today's presentation to a lucrative potential client. Unfortunately, he's just locked himself out of his apartment with everything he needs still inside.
Why should readers care enough to finish the story?
Schadenfreude and dark humor. Let's characterize Randal as a prick. He's a bit short with his girlfriend, looks down on people who have cheaper cars than him, and just has that sleazy businessman feel.
This is a sitcom cliché, I admit, but right now I want to illustrate the mechanics of plot more than produce something brilliant. Throw in enough dark humor and slapstick comedy and there might be something here. People love to hate on jerks in suits.
At this point, creative writing teachers might be getting frustrated. You need a fully realized character to create a compelling story. This isn't enough for that, they'd say.
They're right, but it's almost always a bad idea to put all your details about a character in the exposition. You only need enough to orient the reader. However much you put in the exposition, you should have around 5 times as much in reserve that you can layer in at story-appropriate moments. As a writer, it helps if I know about the time Randal jumped a fence to get back a ball when he was 8, and almost got mauled by a pack of vicious Chihuahuas dressed in cute little Seattle Mariners uniforms, but the reader doesn't need to know about that yet. Depending on how the story goes, they might not ever need to know.
That's a big part of in media res. It's often best to start as close to the rising action as you can without confusing readers. Every additional detail you add at the beginning of the story is one more detail the reader has to go through before getting to "the good stuff." It's an artistic choice as to how much is too much, but a fully realized character is revealed throughout the course of a story. They don't have all their secrets dumped up front.
Now that we know who he is, we need to make this jerk's life worse. One way of describing rising action is as a try-fail iteration. Randal tries something to get back into his apartment. It fails, so he tries something else. That fails even harder (or succeeds just enough to leave him in a worse situation than before). That's the 'action' part.
The 'rising' part comes from increasing stress. In this case, it's simple. The longer it takes for Randal to break into his apartment, the later he gets. If he's too late, he'll lose both his client and the promotion, and then the bookie will be inventively malevolent to Randal's thumbs and knees. The clock is ticking.
The consequences of failure should also increase in severity. That's how readers know this means something. The more Randal is willing to hurt himself to get back inside, the more important the promotion is and the more he's invested in his actions.
Let's try this:
Action: Randal tries the door several times, just because he can't believe he locked himself out.
Consequence: He's just wasted some time.
Action: Randal considers calling his girlfriend, but decides not to because he's not too happy with her and doesn't want her to gloat.
Consequence: He's wasted a bit more time thinking about it.
Action: Thinking about his girlfriend reminds Randal about the emergency key hidden under the mat. He checks.
Consequence: It isn't there. His girlfriend must have taken it.
Action: Randal pounds and kicks the door in frustration.
Consequence: He hurts his foot.
Action: The pain drives some sense back into him. Swallowing his pride, he calls his girlfriend.
Consequence: It goes straight to voicemail without ringing. He remembers her telling him about having to go in early to work today. He rails against an uncaring and cruel fate.
Action: Running out of time, Randal decides to try his balcony. He's convinced himself that he left the balcony sliding door unlocked, and that would be the way in. Unfortunately, his is a third floor apartment, and it will take some acrobatics for him to actually get to the balcony from the outside. We wouldn't want to make it too easy for thieves.
Consequence: Randal takes a look at the plunge and the climbing it would take to get to the balcony, and decides to wait for his girlfriend.
Action: The bookie calls.
Consequence: Randal doesn't answer, but this reminder spurs him to try for the balcony anyway.
Action: Randal tries to get to the balcony.
Consequence: Randal is not as athletic as he believes. He gets stuck halfway. Can't go forward, can't go back.
Action: While he's worrying about falling to his presumed death, his girlfriend calls back.
Consequence: Randal realizes that if he can find a way to answer, she can get help.
At this point, it can't believably get much worse, not without either throwing in unreasonable surprises or a vengeful eight-year-old with a slingshot and too much spare time, so let's move to the climax.
Action: Randal wrestles the phone out of his pocket.
Consequence: Success, kind of. He takes the call, but before he can explain what he needs, he drops the phone.
Action: Randal desperately grabs for the phone.
Consequence: While grabbing for the falling phone, he loses his grip and falls.
It looks like he's just failed at life.
A jerk in a suit falling from a second-story balcony isn't the kind of thing that goes unnoticed. Let's let events progress naturally. When Randal wakes up, he's in an ambulance. His girlfriend's called 911 and is hovering over him, concerned.
The bookie's car turns into the apartment complex parking lot, but the presence of the police and an ambulance scares him off. Randal's girlfriend mentions something about an "attempted break-in."
But wait? How has Randal's situation changed? Did he lose the client? Nah. He's earned a reasonably happy ending. After the police leave, his girlfriend tells him she called corporate. At the mention of ambulances, they contact his client and the presentation's been rescheduled. He's bought himself some time and is a little wiser for the ordeal. He'll definitely remember his keys next time.
And thus, we have a plot.
Verisimilitude in Plot
In order for plots not to feel formulaic and forced, the rising action and climax, along with all the stumbles along the way, should flow naturally out of the characters and situations. An angry character can be expected to make a bad situation worse by getting angry at a bad time, and people intent on climbing the career ladder can be expected to have complications regarding their career.
That's easier said than done, and like everything it takes practice.
The story outlined above is nothing ground-breaking, but should be good for a few laughs. One important thing to know is that, because the plot depends on Randal having a third-story apartment, there has to be mention of it earlier. If it comes out of nowhere, there's a chance it will strike readers as "too perfect." On the other hand, if I drop a full description of Randal's apartment, from how many house plants he has to what's molding in his refrigerator, into the exposition, there's a chance it will strike readers as an infodump. And if I just come out and say it's a third-story apartment, readers might find it too direct. Sometimes they're picky like that.
Another way is to subtly introduce it as part of characterization. I could open the story like this:
Randal stopped at the top of the stairwell. Up here, looking down on the cars parked at the apartment complex, he was a king, far removed from the pettiness and mundanity of their lives. While they hadn't recognized his greatness yet, today was another huge step toward the inevitable. Nailing this presentation, landing this client, would secure that promotion and he would be able to leave the little people further behind.
He was halfway to his car when he realized he'd left the presentation inside. He dashed back up the stairs, cursing the world. He didn't have time for this. Not with Trevor [I'll reveal him as the bookie later] getting impatient.
Without explicitly saying that Randal has a third-floor apartment, readers have enough info—"top of the stairwell," "dashed back up the stairs"—that they'll be really surprised if Randal ends up having a first-floor apartment. Even better, these hints also double as action and characterization. Subtlety can work wonders.
The Google says...
Plot Strategies - A more advanced discussion about plot and a list of various structures.
More on Plot Structure
The 4 Story Structures that Dominate Novels - More ideas for overall plot shapes
Warpcore Science Fiction Plot Generator - Hilarious