The central theme or idea of a story is the message that the writer wants the audience to understand after watching his movie or reading his book.
Some believe that a story should not have a central theme or idea at all, that it should be written just to entertain. But the truth is that stories with a powerful message are generally more popular and easier to understand.
You can express the main idea in three ways: dialogue, plot or character.
The central theme or idea should not be expressed as an essay though, the characters of your story should not sound like professors giving a lecture to their students. Dialogue is a powerful instrument but it risks to become the ultimate obstacle to the audience who’s trying to enjoy the story.
A few lines will be enough to deliver the message, but they should be a subtle reference to the theme, not an explanation. And most importantly, they must be coherent with the dialogue of the scene and the personality of the character.
For example, imagine an episode of Law and order summed up by a detective saying to a criminal that just got caught the line “You can’t escape justice”.
Now imagine the same situation but with the detective saying “A person who commits a crime is pursued by the law enforcements, who have enough power and resources to track down and arrest the criminal. Afterwards he will have to face a trial that will determine if he is guilty or innocent”.
Nothing in the last statement is false. In fact, that sums up every Law and order episode ever. The problem is that explaining is not something the dialogue should do. The audience has already seen the detective working on the case, the DA gathering the evidence to build an argument against the accuse, and the jury pronounce the criminal guilty or innocent. The point has already been proved by the plot itself.
Plot
It might seem difficult to express a central theme or idea through the plot because it means trying to translate a concept into a series of actions.
But the truth is that the plot should be the one “doing the heavy lifting”, not the dialogue. A concept expressed through a gesture, an emotion, a location will resonate more with the audience than a lecture conveyed through dialogue.
As I said, it might seem hard at first but it’s not. Think about how the most famous fairy tales use just plot to teach an important lesson.
Little Red Riding Hood is about a little girl who ends up in trouble because she decides to trust a stranger. No character (in any version of the tale) says directly to the audience “Remember kids, you should never trust a stranger that approaches you in the street”, and yet we understand the key message anyway.
We understand that the Big bad wolf is an allegory for a stranger or in general a bad temptation that will put a little girl in danger because the actions taken by the protagonist mimic the action taken by real life people when faced with a temptation.
Character
We might not notice the clever analogy of the plot or the subtle reference in the dialogue, so the ultimate resource to use is character. By making us empathize with one of the characters, the story doesn’t just manages to “hook” us, it manages to make us understand the nuances of its theme.
Basically if the “With great power comes great responsibility” quote is indecipherable for some people, they can still comprehend the main idea of the 2002 Spiderman movie by watching a young and inexperienced Peter Parker cope with his newfound powers.
To give a practical example of how to express the central theme or idea. here’s how the 2018 movie “Annihilation” by Alex Garland manages to send a message about self destruction.
Also, I should say that the books on which the movie was based (“The Southern Reach trilogy” by Jeff VanderMeer) are very different from the movie itself. Here I will only be talking about the movie.
Annihilation’s central theme or idea
Dialogue
“I’d say you’re confusing suicide with self destruction. Almost none of us commit suicide, and almost all of us self-destruct. In some way in some part of our lives. We drink or we smoke. We destabilize the good job or the happy marriage. These aren’t decisions, they’re impulses.”
This quote from the movie summarize part of the central idea of self-destruction. These lines are brought up organically in the dialogue and they’re delivered by Doctor Ventress (a psychologist) while talking to Lena (the protagonist).
Lena’s husband was part of the team that preceded them in the mysterious Area X and (apparently) the only survivor. Lena suspects that he decided to join the team in this “suicide mission” because he had found out about her affair with another man. Knowing that Ventress had examined him, Lena starts the conversation hoping to find out if the Doctor can confirm her suspicion.
Ventress, finding herself in an uncomfortable situation, decides to avoid addressing directly Lena and uses the words “us” and “we” instead, so that what she’s about to say sounds less like an accusation.
This line manages to do two things: give the audience a general idea of what the movie is about and hint that Doctor Ventress knows about Lena’s marital problems.
Plot
The plot makes multiple subtle and not subtle references to the self-destruction theme, here’s some examples:
Cass (the anthropologist) is killed by a bear-like creature that is later able to trick the rest of the team by imitating her voice and attack them. After the attack, Josie explains that the reason why the creature could imitate the human voice is because after killing Cass, it must have assimilated part of her DNA. Therefore Cass “became” the creature that killed her.
Josie (the astrophysicist) decides to stop fighting the change occurring in her body (Area X is slowly transforming the DNA of all the members of the team) and embrace it. The movie hint to the fact that she let herself transform into a humanoid plant and stayed in Area X.
When Lena finally reaching the destination of the mission (the lighthouse) and finding out that Doctor Ventress has “merged” with the alien creature that created Area X. Ventress says that the alien is absorbing whoever / whatever enters Area X and that it will grow until it will have annihilated everything. Then she herself gets destroyed by the alien creature inside her.
In the second part of the scene, Lena fights the humanoid created by the alien to escape the lighthouse. The creature seems to imitate her movements and even take her appearance. She manages to leave and kill it with a flash grenade that will set the lighthouse on fire and kill the alien.
Area X itself is a space where the DNA of each plant animal or human is altered while they’re still alive. So much that at the end of the movie the Lena that comes out of it is not the same person that went inside, since both her body and her mind have been altered.
Character
Each character in the movie has the tendency to self-destroy, for different reasons and in different ways.
- Kane (Lena’s husband) volunteers to participate in a very dangerous mission because of heartbreak
- Lena volunteers to the expedition out of guilt for betraying Kane
- Ventress has cancer, knowing that she has to die she decides to join the team
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Anya is an ex addict
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Josie used to hurt herself to feel alive
- Cass’ daughter just died of leukemia
All those character’s backgrounds give them a reason to have the desire to destroy themselves. Area X could also be interpreted as an allegory for depression since it changes and consumes the people that enter it.
Annihilation expresses a deep concept in a clever and not persistent way, which is ultimately what makes this movie enjoyable to watch.