There are many ways to enhance the main plot of a film. You can flesh out your protagonist, establish a story structure that keeps the audience engaged, and fine tune the plot points that move the story forward. But did you know that introducing subplots can enhance your film’s main plot? Understanding how a subplot functions and serves the main plot can give your film the depth you desire. So, what is a subplot of a story? And what is the definition of subplot? We’ll answer all of that and more in this article.

Subplot definition

First, let’s define subplot

While subplots have similar elements to a main plot, they function differently. A subplot (aka a B plot or B story) needs to adhere and support a film’s main plot in order to serve a purpose in a film. Otherwise, the main plot and subplot can run parallel with little relevance to each other becoming a waste of screen time. Let’s get an understanding of the subplot definition.


What is a subplot?

A subplot is a secondary plot used in film and television that receives less screen time and emphasis than the main plot. Subplots may never intertwine with a story’s main plot, but to be effective, work to enhance the main plot of a film. B plots often have the same general components and plot structure as a main plot, but have fewer plot points and beats.

What is the definition of subplot in literature? Similarly, in literature, a subplot is a secondary plot that runs parallel to a story’s main plot and supports it.

What is a subplot’s function?

  • Add thematic depth
  • Test a film’s protagonist
  • Reveal more character traits
  • Establish different points of view

Subplot definition and uses

The value of subplots

So, what is a subplot good for? Although the subplot definition is very general, a B story can enhance a story’s main plot in many different ways. The first way being they resonate the main plot’s overall theme. While the actual action that occurs in a B story may be far from what is occurring in the main plot, they can both thematically resonate to strengthen the overall theme of a film.

The second value of a subplot is its ability to better establish the world of a film. Although the definition of subplot in literature is similar to how B plots operate in film, they differ in one specific way. Films are a visual medium. Some subplots often allow for various points of view and thus allow us to visually see different parts of the film’s world. This can be a crucial plot device in providing context for the main plot line that moves the story forward.

Lastly, a B story can help reveal traits of a character that can help establish empathy with an audience. This can be done when a subplot challenges a character through a relationship, career choice, or reaction to a situation. To better understand the value of B plots, check out Lessons from the Screenplays analysis of how subplots are used to enhance the story of the film Hidden Figures.

Hidden Figures  •  What is a Subplot?

Subplot Examples

Types of subplots

To start incorporating subplots into your film, it's important to first understand the types of subplots that exist by analyzing different subplot examples. The vehicle and type of a subplot can vary based on a film’s genre and plot structure. All, however, should serve the main plot.

B Story Examples

Add a romantic B story

This is one of the most commonly used subplots as it is quite easy to weave into a film’s main plot. Your protagonist meets someone and begins a relationship while the main plot line is occurring. Romantic subplots can create drama and empathy within the main plot line as in one of the best Christopher Nolan's movies, The Dark Knight

Although it is not a part of the main plot of Batman saving Gotham, Bruce Wayne’s relationship with Rachel is important in humanizing our protagonist Bruce as well as creating conflict in his objectives.

This scene from The Dark Knight weaves together this romantic B story into the main plot through the actions of the film’s antagonist the Joker, making for a highly dramatic scene.

Subplot Examples  •  The Dark Knight

B Plot Examples

Bring conflict to the B plot

Creating conflict between characters or within a subplot can help add tension to your script especially if it is a more serious, dramatic story. The conflict of a subplot can also help reveal traits of your story’s characters in the face of controversy.

In Good Will Huntingthe main plot follows Will and his journey in becoming more open to the world his genius opens up. The B plot follows the conflict between Sean, played by Robin Williams, and his old roommate, Professor Lambeau. 

We used StudioBinder's screenwriting software to break down this scene from the Good Will Hunting screenplay. In this scene, the B story comes to a climax and effectively builds drama and emotion right before the cathartic climax of the main plot.

Subplot Example in Good Will Hunting  •  Read Full Scene

B Story Examples

Add a B story to existing character arcs

This type of subplot may have to do with any emotional, spiritual, or intellectual growth that occurs for a character. Oftentimes this can be a byproduct of or related to a character’s main goals and can contribute to the character development of a protagonist.

The character development in one of the best movies of 2017, Lady Bird, is cleverly illustrated by Lady Bird’s disdain for her real name. At the end of the film, when she introduces herself as Christine, we see the completion of her character arc and her acceptance of who she is.

Subplot Examples  •  Lady Bird

B PLot Examples

Bring comic relief to the B plot

What is a subplot in a comedy? Subplots that serve as a comic relief can diffuse tension which can enhance the experience of a film. Main plot lines of comedies usually have some element of drama. Ensuring there’s a consistent comedy relief is a great way to fulfill audience expectations.

In one of the best comedy movies of all time, Superbad, the main plot follows Seth and Evan as they try to get alcohol for their high school party. The B plot follows McLovin and his night with two cops-turned-buddies. This B story serves as a comic relief that the film cuts to when the main plot becomes more and more dramatic. This scene, for example, does little to move the main plot forward, but does everything to leave us in stitches.

Subplot Examples  •  Superbad’s McLovin B Story

There are many creative ways to incorporate subplots into a story that may not fall directly into one of these categories. Writers have found unique ways to introduce and include subplots in a narrative through different means.

To recap, what is a subplot’s function? No matter what genre you are writing for, the B story should always enhance the main plot of the film.


Elements of Plot Structure

Subplots are a key component to a well-developed story. Understanding plot structure will help you develop both your main plot lines and subplot lines so that together they can build dramatic tension and create an impactful climax. Learn more about the elements of plot structure in our next article.

Up Next: Plot Structure →
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