Making Friends and Learning Things in a Four-Act Structure
If you consider the midpoint of your story as similar to a plot point that turns an act from one to another, then the midpoint of your screenplay can serve the same function. Instead of the structure of your story being three acts in which the second is twice as long as the first and third, by viewing the midpoint as an act break, you create four acts all of generally equal length.
While this has no bearing on acts one or three, it does change how you view Act Two. In a four act structure, “Act Two” (the first half of what we used to think of as Act Two) becomes the part of the story in which your hero goes from having his or her life upended by the events at the end of Act One and now has to struggle with how to respond. It is in this part of your script where the hero begins to learn skills, make allies and acquire the knowledge that s/he will need to fulfill his or her task. This is the period in “Star Wars” where Luke finds Obi-Wan-Kenobi and Han Solo; in “Buffy, the Vampire Slayer” it’s when Buffy agrees to listen to Merrick; in “When Harry Met Sally,” this is when Harry and Sally are both single and begin to hang out together. This is the period where buddies struggle with each other and learn how to work together. It’s when the hero relocates to a new environment if necessary. This is the period in which the hero has the experiences that open his or her eyes to what s/he is facing.
In this structural scenario, “Act Three” is the latter half of the old Act Two. This is the section of your story from the midpoint up to the events that make the end inevitable. This is the period in which the main character comes to understand what it is that s/he must do. It’s the point in action movies when the hero forms a plan of attack against the villains. In a love story, it’s usually the point where the main character realizes they’re chasing the wrong person. In a horror movies, it’s the point when the characters realize what kind of demon they are up against. From this point forward, it becomes about the main character using his or her acquired knowledge, skills and allies to escape, conquer, vanquish or win over the people or things they need to resolve their situation. Usually, there is still some piece of the puzzle missing that the main character doesn’t learn until Act Three. The detective knows how the victim died but not who the victim is yet; a lover knows who s/he wants to be with, but that person is about to become unattainable because it’s too late; and the action hero’s most important object/family member/lover/friend is kidnapped and needs to be rescued.