The Screenwriter's Bible, 6th Edition: A Complete Guide to Writing, Formatting, and Selling Your Script (Expanded & Updated)

You may ask, Can the Catalyst also be the Big Event? Sure. Ghost and Regarding Henry are two examples, as is Juno (the pregnancy). Keep in mind that I am presenting guidelines in this book, not hard-and-fast rules.

Here’s the principle: When a story begins, life is in balance. Yes, your hero may have a problem, but it’s a problem he’s always had—his status quo. Then the Catalyst kicks things out of balance and gives the central character a new problem, need, goal, desire, or mission. The central character spends the rest of the movie trying to get things back into balance.

Somewhere in the first 10 or 15 pages of your script (or earlier), something should happen to give your central character a goal, a desire, a mission, a need, or a problem.