Will they follow their dreams and end up at separate colleges, or follow their heart to the same school?
Now we can better understand what this movie is about!
It's that bit of information the producers want us to hold onto that will allow us to build excitement for the movie and remember with ease the main point of the film.
In our fictional romantic comedy, our topic sentence might be Jordan and Willow must decide if their high school love is big enough to span not just one college, but two.
Of course, there is a bit more narrowing that can be done in this process.
Sometimes space does not allow us to give a longer explanation.
While that helps narrow things a bit from the entire genre of romantic comedy, it doesn't really help give us the detail we need to truly understand what is unique about our movie.
However, I can add the thesis statement of Two high school sweethearts ready to embark on the wonderful world of college.
The best way to avoid such a tragedy in your own writing is to get great at setting the stage for your writing. The main idea is the key concept being expressed or examined.
Putting this in our movie frame of reference, the main idea would be the broad context on what the movie is about, or the in which the movie will be viewed.