Many aspiring screenwriters might not be aware of the term “through line” and how it’s frequently used in the development process. When I first broke into the film industry I wasn’t aware of the term myself, and I definitely wasn’t thinking of thematic or emotional through lines when writing my spec script PIERRE PIERRE with my former writing partner. All we cared about was being funny. The protagonist was a Frenchmen who hated everything and everyone. He’s given the task of transporting the Mona Lisa, which had been stolen from the Louvre, and inspired by the Wu-Tang Clan’s “C.R.E.A.M.”, he attempts to sell it on his own. The script was never produced, but it was a big sale and had three different A-list directors attached at different times. The first director was part of a comedy troupe and focused more on comedy than character. The second director, who had made a series of acclaimed, character-driven dramedies, was the opposite: he was all about character and the protagonist’s emotional journey. This director thought our script was one of the funniest he had ever read, but he didn’t think it was “a movie” yet.

This is something you’ll hear if you likewise break into the film industry: “It’s great, but is it a movie?” What this really means is “Is it a good movie?” or, to be more precise, "Is it a movie we can get green-lit?” The above director knew our script needed more than laughs. He wanted us to give the script an emotional through line and the protagonist more of an arc. He knew it was difficult since our protagonist hated everything, but he eventually zeroed in on something. The director suggested turning the Wu-Tang joke into deeper character motivation. Maybe our protagonist would become corrupted by greed when trying to sell the stolen Mona Lisa?

This is a good example of the difference between a plot and a through line: the plot was our protagonist transporting and trying to sell the Mona Lisa, and the through line was that he’d become corrupted by greed and need to reclaim himself at the end. If the protagonist truly hated everything, then he should likewise hate money and reject it. Injecting this through line led to a stronger and richer script. It was still funny, but it was now grounded with a bit more depth. The director had taught us an important screenwriting lesson: a protagonist without an emotional through line is a shell of a character. They’re one-note and have no place to go. Even if the emotional through line isn’t obvious or conventional, it should never be nonexistent.

The longer I worked in the film industry and the more projects I developed, the more I’d hear these questions from producers, studio execs, and directors: “What’s the through line? What does the protagonist want?” After a while, I retained this mindset even when writing spec scripts. Today I would never write a script in which the answers to the above questions isn’t already apparent. I’m also able to spot emotional through lines in the film and television series I watch. In my article Through lines and “The Empire Strikes Back”, I discussed the fundamentals of thematic and emotional through lines in a script and offered a few examples of through lines in classic films (as well as an in-depth analysis of their use in The Empire Strikes Back). The more you become aware of emotional through lines, the more you’ll spot them, and after a while it’s easier to create and maintain them in your own writing.

When writing a script, the writer should always be aware of the protagonist’s driving motivation. In every scene, you should be able to say what they want and whether they’re closer or further to getting it. This is one of the most important aspects to storytelling: there has to be constant motion. This doesn’t mean constant physical motion (although that might be good for an action/adventure), but rather a nonstop tracking of the protagonist’s feelings -- their moments of frustration, of victory, etc. The word “motion” is part of the word “emotion” for a reason. Every scene the protagonist is in should pertain to their greater character arc and their through line should always be cresting to the surface in some way or another.

Think of Martin Brody in Jaws. Isn’t it clear how he feels in every scene? Aren’t his feelings constantly cresting to the surface and revealing that he’s either resigned to his life on Amity Island, or anxious about his duty as sheriff, his children’s welfare, and ultimately his own survival? There is never a scene with his character in which his emotional through line — an ex–New York City cop who’s afraid of water, trying to make his new life in an island town work — isn’t thrashing about with the film’s plot, that a great white shark has staked a claim in the waters of the island town. The plot ends with the resolution of the shark problem; the emotional through line ends when Martin finally laughs with relief and can swim back home. Although a protagonist’s emotional through line is the most important, supporting characters can have them as well. In Jaws Quint and Hooper have contrasting through lines: one hates sharks because of a traumatic event and hunts them to take back control, while the other loves sharks after a childhood incident and studies them to appease his fascination. As with Martin, their through lines are constantly manifesting as they deal with the shark, and even dictate their respective fates. Fundamentally, a through line is an internal story that’s running parallel to the external story. Think of it as another layer that adds depth and soul to your script.

From Jaws to Spider-Man: No Way Home, the protagonist’s emotional journey runs parallel to the film’s plot. Classic movie after classic movie will reveal this pattern. Aspiring writers should watch these and other films with this mindset. How are they revealing the emotional through line? How are the protagonist’s emotions tracked as they react to tragedy or triumph? How does their dialogue and action at certain moments convey their feelings? Are they closer to their goal in one scene and then further away in another? Take this knowledge and then apply it to your own writing.

There should never be a scene in which your primary characters aren’t winning or losing more than they were in the prior scene. Even if it’s a minute difference, there should always be a difference. Every scene should be a step backward or a step forward. Whether it’s a quiet moment or an action-packed set piece, it should act as a building block to a larger arc. If you can’t see how a character’s emotional state in a scene differs from their prior scene, you’re likely not tracking it correctly and need to revise. Sometimes it just takes an extra line of dialogue or one line of description telegraphing the emotion (my manager refers to this as “taking the temperature”). Asking all of the above questions is probably the biggest tool when creating a through line and being mindful of the emotional state and desires of your characters.

Once you start examining your characters and their relationship to what’s happening on the page, you’ll learn how to create and maintain an emotional through line.

And then you might not just be writing a screenplay.

You might be writing a movie.