Plot is arguably the most important part of any story. Even complex characters in a richly detailed world won't hold a reader's attention if they don't do anything significant. A plot can be subtle and compact, as in a short story consisting of a single tense conversation, or it can burst with exciting incidents that build to a revelatory conclusion, as in a thriller novel.
To discuss plot, let's consider a highly simplified outline that could serve as the basis for either a short story or a novel:
1. Married couple Ella and Art have both lost their jobs and can't afford to pay their mortgage.
2. They put their house on the market and move in with their grown son, Mike, and his family.
3. Living in Mike's house leads to tension and arguments.
4. Art finds a new job, and the couple is hopeful that they can get their house back before it sells.
5. Ella also secures a job, and they're able to reclaim their house just in time.
The outline opens strong: The characters are in a tough situation that they will have to struggle to get out of. This can be a great way to begin a story, but only if things get worse from there. In this plot, life does become more difficult for Ella and Art. However, the additional problems follow as a direct consequence of the starting situation rather than arising from new obstacles, so while the first half of the outline has promise, it could be better.
Perhaps as the story opens, only Art been laid off, and the couple worries over money. This change leaves room for conditions to deteriorate. It also provides an opportunity to hint at what the worst case will look like so the reader can hope it doesn't happen. If Ella then does something at work that gets her fired, not only has their situation worsened, but Art can blame her for it, leading to all sorts of new conflicts. Remember, the more your characters suffer, the more interesting the story becomes for the reader.
After the midpoint of the example outline, the couple's circumstances steadily improve. That's nice for them as people, but it doesn't make for an absorbing plot. To add tension, just when things are looking up for your characters, snatch away their good fortune and leave them unhappier than before. In a longer story, create a number of obstacles that pile up, and craft a sequence of high and low points.
For the sake of a compelling story, Ella and Art can't simply find new jobs without any trouble. Employment possibilities might be dangled tantalizingly and then withdrawn right as living with Mike becomes more stressful. Or even better: In order to get out of financial hardship, Art must face the tougher challenge of making peace with his son and going to work for him. A plot is stronger when there are connections between the events and threads, so look for ways that these links could test your characters more.
A good resolution unites all the story elements that have been presented so far. If the couple is rescued by a windfall inheritance from a relative Ella never knew she had, it won't be very satisfying for the reader because the happy ending comes out of nowhere. Similarly, if Art is suddenly diagnosed with cancer late in the story when there has been no previous discussion of health, the complication will feel disconnected from the rest of the plot. To write an ending that works, set up all the contributing factors near the beginning of the story. Add an extra layer by introducing a character flaw that will have to be overcome on the path to success.
It could be that Art has always been too proud to take a lower-status position, particularly from his son, but he learns Mike has always admired him and will continue to do so regardless of his job. A source of income may not be enough to save Ella and Art, who are headed for divorce due to all the conflict they've dealt with since Ella was fired. Maybe she's been insisting she was dismissed due to a misunderstanding and has been trying to clear that up. When she makes her case and gets her job back, Art regrets not believing her, and the story ends with a hopeful outlook for the recovery of their marriage. It's not necessary for every thread of the plot to reach a conclusive ending, but make sure they are all addressed.
Here's a revised outline incorporating some of the new ideas:
1. Art has been laid off. He and Ella worry over their financial situation and the thought of having to live with Mike.
2. Mike offers Art a job, but he is too proud to accept.
3. Ella is fired. She claims she's done nothing wrong, but Art doesn't believe her.
4. The couple is barely speaking as they put their house on the market and move in with Mike.
5. Ella discovers evidence of her wrongful dismissal and is excited to share it with Art.
6. Art dashes Ella's hopes by rejecting the evidence and continuing to blame her.
7. Mike tells Art that before this incident, he always admired his father for standing behind his family no matter what.
8. Art realizes he's been focusing on the wrong priorities. He tells Ella that he'll support her in presenting the evidence and that he'll take a job working for Mike.
9. Ella makes her case and gets her job back. The couple is able to reclaim their house and expects to heal their marriage.
Of course there are many other possible variations for this basic outline. Don't commit to the first version of a plot that you come up with, even if you've already written an entire novel draft to develop it. While some writers are skilled at advance plotting, most of us have to write our way through a story to figure it out, and only then can we start to consider how it could be better. Rewriting at the plot level takes time and effort, but improving a story's plot is the most important thing you can do in revision.