The Situation is the nucleus of your story: it contains the kernel of your conflict from which the rest of your storyline will grow.
A real story cannot exist without some sort of conflict.
If, though, you don’t have a specific message, you must then begin your story by thinking up a good central conflict. And by “good,” I mean a conflict that’s important enough to hold people’s interest.
(If, for example, you’re hungry for cookies but you’ll only allow yourself one cookie, and then you find in your cookie jar two peanut butter and two sugar, there is here a certain conflict that you must resolve — i.e. you must choose between those two things — but it isn’t the kind of conflict upon which a story can be built. Why? Because the choices aren’t strong enough to be of lasting interest. To be of lasting interest, the conflict must be of certain importance to many people. That last thing is known as universality. Universality is important because stories must appeal to a range of people.)
Often, new writers ask if they should decide their theme first, or their plot first. The answer is, it doesn’t matter. Either method is okay.
The method you’re most comfortable with is a personal preference. Sometimes, in a fit of inspiration, you get an idea for a theme, and you must then figure out how to dramatize that theme, the act of which is called plotting.
Or sometimes you get a good idea for a story — a real clash of desires — and you must then, if you’re philosophically inclined, figure out a way to convey a universal message which that conflict represents (for example, honesty in the case of the movie Quiz Show, which I thought was a unique and excellent idea).
If you don’t have a universal message — i.e. a theme — that’s okay too. Your story will then be a plot story without an added level of depth. Soap operas and most commercial fiction, as I’ve also said, are examples of this.
The hooker-with-a-heart-of-gold is one of the most famous (and played-out) Situations there is: Pretty Woman, with Richard Gere and Juilia Roberts, used it.
Leaving Las Vegas, with Nicolas Cage and Elisabeth Shue, also used it, though that story gave it a distinctly dystopic twist.
The reason the hooker-with-a-heart-of-gold is such a popular Situation is that it has a built-in conflict — a woman who betrays a certain respectability and then falls in love — and also because it’s inherently sexual, which is one of the most universal desires there is.
Here are some less common Situations:
The Situation of Crime and Punishment is this: a man who believes that great people are above conventional morality commits a crime and is then condemned by his own moral sense.
The Situation of Madame Bovary is this: a small-town French girl, bored by her petty bourgeois marriage, engages in numerous adulteries and dies as a result.
The Situation of the movie Amadeus is: a marginally gifted musical composer named Antonio Salieri grows increasingly consumed by his jealousy over Wolfang Amadeus Mozart’s prodigious musical talents and so plots and carries out Mozart’s murder.
The Situation of House of Leaves is: a mysterious house that’s bigger inside than outside, containing endless unlit hallways, is explored by the family who’ve just moved in — explored until it almost kills them. (This Situation is symbolic of their marriage.)
If you’ve ever read a book or watched a movie where the characters do little more than engage in long, philosophical discussions, then you’ve seen an example of a plot that doesn’t support its theme — which is to say, a theme that is not well integrated into the plot. This is a flaw in the storytelling, and the basic standard of measurement for that is this: how complex are the events of your story, and are they complicated enough to support the philosophy that you’re putting into the mouths of your characters — without, mind you, taking readers out of the framework of the story?
The main point here is that theme, if it exists, must be integrated into your plot. This means, among other things, that when you’re searching for a good Situation — i.e. a good central conflict — you must find a Situation complex enough around which a whole story can be built, and which will support your theme.