Every story must start with a goal and end by showing whether the hero got that goal or not. Yet most people write a story from the beginning but it can be more useful to start at the end. By working backwards from the end, you’ll know exactly how the story is going to end. That way you’ll know how to introduce crucial ideas earlier in the story.
Even if you don’t know all the details of your story yet, start at the end with the final emotional impact you want the audience to remember. That final scene must be emotionally satisfying and memorable because that encapsulates the entire tone of the complete story.
The last scene in “Back to the Future” shows the hero and his girlfriend climbing into the time machine with Doc, the mad scientist, as he’s about to head into the future. The joke is that Doc needs the hero and his girlfriend to fix a problem with their kids.
The last scene ends with a joke, reflecting the comedic tone of the entire story, and gives us one last sight of the time machine before it takes off. The emotion reflects the humor and silliness of the story and the time machine.
In “Don’t Breathe,” the last scene shows the hero leaving town at the airport with her little sister. This was the hero’s original goal from the beginning so the last scene shows she finally succeeded.
Since “Don’t Breathe” is a horror story, the last scene also includes the hero watching a news story on TV showing that the villain survived after all, although he doesn’t reveal that the hero exists or that the hero took his money. Thus the last scene ends with a sense of dread that the villain is still alive, but also a sense of hope that the hero succeeded in saving her little sister.
In “Star Wars,” the last scene shows the hero getting a medal during a ceremony honoring the heroes of the battle. The hero stands triumphant knowing that he started the story as a farm boy and ended the story as a war hero who finally got the amazing adventure he always wanted.
Pick a favorite movie and watch that last scene. What emotion does that last scene evoke? How does this last scene embody the tone and spirit of the entire story?
In your own story, decide the type of emotion you want an audience to feel in the last scene. How can you visually evoke that emotion? How can the last scene embody the tone of the story? (A comedy often ends with a last joke, a horror story often ends with a disturbing threat, an action thriller often ends with a triumphant moment, a romance often ends with a moment of love, and a drama often ends with a happy, tragic, or ambiguous ending.)
Make the last scene memorable and you’ll have a clear target for where the rest of your story must aim at. This will help create a far more unified story than if you had just started at the beginning and kept writing until the end.