When I studied screenwriting at UCLA I was quite dubious about one teacher. I doubted whether he knew what he was talking about. He didn't explain the reasoning behind his principles very well, he just pronounced wisdom as if he were the Oracle of Delphi and we were to accept it on faith. He didn't give you the why behind his pronunciamentos, so they came off as Platonic ideals unconnected to the facts of reality.
One of his rules was "Don't keep secrets from the audience." This baffled me. What about plot twists? Reversals? Surprise endings? Whodunnits? There were enough obvious contradictions to his rule that I dismissed the teacher as a bizarre old coot.
Today I was working on a romantic drama plot that I've been struggling with for months. Part of the plot involves a spy, whose identity is revealed to the audience late in the play. Suddenly it occurred to me how much more interesting it would be to reveal his identity to the audience early and show his struggle with his duel loyalties. The plot twist would come around the end of Act I instead of the end of Act II -- which would give me more substance for those difficult stretches in Act II.
I realized that I was following the old coot's advice! When I kept the secret from the audience, I was creating a coup de theatre: melodrama. Now that I let the audience in on the secret, the spy's story becomes drama, as the audience sees his internal struggle.
I would put the old coot's pearl of wisdom like this: Consider not keeping a secret from the audience. Obviously, there are some secrets that should be kept from an audience, otherwise Agatha Christie would not have had much of a career. However, it is a good exercise to play around in your imagination with those late plot twists and see what happens if you let the audience in on something early.
Ayn Rand makes a fascinating identification in The Art of Fiction. She says suspense is letting the reader in on the author's intention. Little hints of what is to come create expectation -- suspense. You could say suspense comes from not keeping secrets from the audience.
Secrets and revelations tend to be the stuff of melodrama. To dramatize an internal conflict the audience has to be in on the facts and circumstances that create the conflict.