Screenplays aren’t divided into three Acts, but four. Each Act tells a mini-story all by itself which strung together creates a coherent whole.
In outlining your story, start with the big question: what is your story about? In “Die Hard,” the story is about a man trying to get back together with his wife when terrorists get in the way. In “Saving Private Ryan,” the story is about whether the American soldiers will save Private Ryan or not. Every story has a big question that’s posed in the beginning of the story and only answered at the end.
The story’s Big Question is what attracts people to your story. Many Hollywood blockbusters ask Big Questions right up front so the audience knows exactly what the story is about such as can a Marine get back his legs (“Avatar”)?The answer to this Big Question only comes at the end.
Act I poses this Big Question and Act III answers it. After you’ve identified this Big Question, now the task of the rest of your Acts are to take the audience from your beginning to the end.
Consider “Star Wars” to understand this four-part story structure. The Big Question is whether Darth Vader will succeed in defeating the rebel alliance. The Act I mini-story is whether Luke will get off his planet. By the end of Act I, we see that he does.
Act IIa is whether Luke will get to his destination,which the Death Star blows up. The end of Act II shows that Luke has failed and gotten caught by the Death Star instead.
Act IIb is whether Luke can get off the Death Star. By the end of Act IIb, Luke has escaped along with Princess Leia.
Act III is whether Luke and the rebels can defeat the Death Star. By the end of Act III, Luke has succeeded, which also answers the Big Question posed at the beginning of whether Darth Vader will defeat the rebel alliance, and the answer is no.
Take another movie like the 1973 hit “Paper Moon” (which you can watch for free on Hulu). “Paper Moon” is about a con man who takes in a little girl. The Big Question posed is whether the con man will get the little girl home to her aunt and uncle’s house.
The mini-story in Act I is whether the con man can get rid of the little girl. By the end of Act I, the answer is no because the girl threatens to call the cops on him and his cons unless she pays him $200.
Act IIa is whether the con man can pay the little girl her $200. Together, they perform various cons until they collect enough money and it appears that the con man can pay the girl $200 after all.
Act IIb is when the con man falls in love with a stripper and starts spending money on the stripper, essentially blowing the little girl’s money that’s due to her. This mini-story is whether the little girl can get rid of the stripper, which she does by conning the con man.
Act III is when the con man fools a bootlegger, only to be caught when the bootlegger’s brother is the town sheriff. The mini-story is whether the con man can get away with the con and by the end of Act III, the answer is no when the sheriff beats him up.
Finally at the end of Act III, the con man gets the little girl to her aunt and uncle’s place, only she doesn’t want to stay. Instead she rushes back to join the con man and travel with him from now on. So the Big Question gets answered in that the little girl does get home, but she’d rather stay with the con man, who might be her real father after all.
Take your movie idea and identify the Big Question that defines what your movie is all about. Then divide each Act into mini-stories that lead the audience from the beginning to answer the Big Question. Only after you know where your story is going should you begin doing any actual writing.