Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Exposition (Initial Situation): Voice of the Prodigal Son
Glory tells Ames that Jack Boughton has called from St. Louis and plans to come home. Ames feels anxious at this news—Jack is the favorite son of Robert Boughton, and the most troubled. In his letter, Ames tells his son he'll love him no matter what.
Right off the bat, we don't know much about Jack Boughton or whether we should trust Ames's concerns about him. We don't yet have specific actions to judge him by; we mostly just have Ames's vague impressions. Will Jack live up to the hype?
Rising Action (Conflict, Complication): The Prodigal Son Returns and Gets on My Nerves
Jack comes home to Gilead, to the joy of his family and the annoyance of Ames. From where Ames stands, it looks like Jack is plotting to replace him as Lila's husband and their son's father. Adding insult to injury, Jack challenges Ames on his religious convictions and beliefs.
At this point, it sure looks like Ames is right to worry. At least from his perspective. And that's the thing. Should we trust Ames's perspective? Is he right about Jack or is he just jealous of him, his youth, and his possible intentions regarding Lila?
Climax (Crisis, Turning Point): The Prodigal Son Reveals His Secret
Jack admits to Ames that he has a wife and son but is at risk of losing them. His wife is black, and there are laws and social mores against interracial marriage. Plus, Jack's alcoholism and meanness make him ill suited to be a husband and a father.
The crisis, oddly enough, is something of a blessing for Ames. Jack may be as mean as he remembered, but the young man isn't after Lila. So Ames finds it easier to respond to him now.
Falling Action: The Prodigal Son is Blessed
Ames overcomes his dislike of Jack Boughton. He forgives Jack and gives him a blessing. Jack has become a son to him—fitting since Jack was named after John Ames.
At this stage, the barrier between Ames and Jack dissolves, and everything falls into place. Ames can be gracious, and Jack can be honest.
Resolution (Denouement): The Prodigal Son Departs
Ames promises Jack that he'll say goodbye to Jack's father for him. Jack leaves. Ames concludes his letter, hoping that by means his prayers and his letters, he'll be close to his own son.
At this final stage, we understand better why Ames has told this story to his son. He wants him to know that he is loved regardless of how deserving he is of that love. With his parting words, Ames doesn't give his son a litany of dos and don'ts. He keeps it simple. Be brave. Be useful.