Linda Seger describes the catalyst scene as one that sets the story in motion. Some refer to this scene as the inciting incident, but this may be a little confusing if not positioned early, as I shall explain below.
The first catalyst, or inciting incident as some may say, occurs within the first ten or fifteen minutes in a film. Seger gives us the following examples: The death of the gladiator’s wife in Gladiator, the quitting of the job in American Beauty, the solving of the math problem in Good Will Hunting or the shooting in Saving Private Ryan.
Seger makes the point that strong catalysts ought to emerge through actions and events rather than unfold through long verbal exchanges. Although a catalyst most commonly occurs in the first half of Act One they may occur throughout the script. For this reason I prefer not to refer to the catalyst as the inciting incident.
“A catalyst scene is a call to action.”
Seger provides further examples: Let’s say two people meet at the first turning point in Act One, and as a result fall in love. Or, say, in Act Two a detective uncovers an additional clue which leads him to change his approach to an investigation. Or, perhaps, at the midpoint a protagonist learns about a new drug which might cure her of her cancer. All these bits of information serve as catalysts which initiate subsequent actions that propel the story forward.
The catalyst scene is a spur to action initiating a series of cause-and-affect events in a story.