We know any drama ends when we find the answer to the question which gave rise to it. When we discover the answer simultaneously with the hero, the dramatist has done a very good job indeed.
An example is CASABLANCA. Here, the hero, Bogart, is in exile trying to get over what he understands as the betrayal by his one true love. She (Ingrid Bergman) shows up, and he endeavors to get revenge (he denies her and her husband the Letters of Transit). In Act Three he finds she didnot desert him in Paris, that her husband, who she had thought dead, had escaped from a concentration camp, and that she’d found it her duty to care for him. Now Bogart finds she is still in love with him, Bogart, and they scheme to escape from Casablanca and live happily ever after.
BUT. At the last moment, confronted by the Bad Nazis at the airport, Bogart gives the Letters of Transit, with which he and Bergman were going to escape, to her and her husband, and goes off into the mist with Claude Rains to fight Nazis.
This is damned good writing. A man thinks he’s getting over a problem, the problem reasserts itself (Bergman shows up), he tries to deal with it through revenge and then through fantasy (they can pick up where they left off), but finds these do not answer the question. The question is, “How does one deal with Betrayal?” He has tried distance, rage, and alcohol, and they do not work. The true solution, he finds, is, “DO NOT BETRAY OTHERS.” The answer, then, is found because the hero reformulates the question. It used to be, “What do I do about Ingrid Bergman?” but the deeper question, which alone has an answer, is, “WHAT KIND OF MAN AM I?”
Read the whole thing at the link.