Without a strong sense of cause and effect, your story will come across like a contrived collection of random scenes. Every event, character and object you introduce in your screenplay should have an effect on what happens in the ensuing scenes. This will make the action credible, logical, compelling and complex.
Cause and effect is more than just one scene leading to the next. Anything that happens in a script needs to be carried through to its endpoint. Often a writer will include an event in a script in order to get a character into a certain situation, but then never refer to the event again. Recently, I read a suspense script in which a published exposé written by the protagonist about student athletes using steroids earns the protagonist enemies who engage her in a dangerous battle for survival. However, once the battle begins, the exposé is forgotten. We never find out how the protagonist even knew about the drug-taking, and there are no outside ramifications for the school or any of the athletes involved. This ultimately renders the set-up unbelievable and forced.
When cause and effect are used properly, they can create considerable tension in a story, as the events snowball, generating greater and greater problems for the main character. In THE APARTMENT, Shirley MacLaine is an elevator operator having an affair with a married executive. At an office party, the executive’s drunken secretary reveals to MacLaine that she too had an affair with the executive, as have several other women in the company. This conversation leads to MacLaine attempting suicide in Jack Lemmon’s apartment, where she and her lover had been meeting. In many scripts, this would have been as far as the cause and effect would go, since the two leads have now been thrown together. However, screenwriters Billy Wilder and I.A.L. Diamond exploit the ramifications of the party scene to their maximum potential. The executive, annoyed with his secretary for putting a crimp in his love life, fires her. As a result, the secretary calls the executive’s wife and tells her about her husband’s philandering. The wife files for divorce, leading the executive to propose to MacLaine, which undermines the romantic hopes of Lemmon, who has fallen in love with MacLaine. One thing leads inevitably to another in a richly woven narrative tapestry. There is no need to contrive any external obstacles or complications, because by simply playing out the effects of the early events, conflict naturally builds. If just one story thread of this plot were removed, the entire script would unravel.
The film CHANGING LANES is a simpler, more easily decipherable example of the use of cause and effect. After a car accident, Ben Affleck heartlessly abandons Samuel Jackson at the scene, but also unwittingly leaves behind an important legal document. The two men engage in an escalating battle in which their vengeful actions towards each other lead to greater and greater retaliations. Every time one of them has second thoughts and tries to end the battle, the consequences of an earlier action he took causes his opponent to make a move that starts the battle over again, with higher stakes.
Even minor events in a story need to have ramifications. For example, if a character gets into a fight in one scene, he should have bruises in the next scene, and other characters should comment on them. This not only helps the logic of your plot, but also adds texture to it. In THE APARTMENT, Jack Lemmon spends a winter night locked out of his apartment. As a result, he gets a cold, the symptoms of which are used as gags in the ensuing scenes.
Any scene that you can remove from your script without changing anything that comes before or after is extraneous and not organic to your story. To make it organic, try to find a way to tie it into the plot by having the scene be a clear result of something that happened earlier and lead to something that happens later. In this way, your narrative becomes a tightly structured and complex whole, rather than a loosely assembled assortment of arbitrary parts. Scripts with strong cause and effect are impossible to put down, and will keep an executive or story analyst reading eagerly right up to the end.
