It goes without saying that you must interest your audience, but you must also satisfy them—­gratify the curiosity you have earlier aroused.  It is all very well to write an “absorbing” story, in which the excitement and expectation are sustained up to the very last scene, but be sure that the theme is essentially such that in the last scenes, if not before, your action will unravel the knot that has become so tantalizingly tangled as the play proceeded.  No matter how promising a theme may be in other respects, it is foredoomed to failure if from it comes a plot of which the spectator will say as he goes out, “It was a pretty picture—­but I couldn’t understand the ending.”

Another thing:  If it is important that, in every case, the spectators must be “shown” what happens in the working out of a plot, it is equally important that they be shown why it happens.  This also has to do with sound and comprehensible motivation.  “It is not so much a case of ‘show me,’ with the average American, as a common recognition that there must be a reason for the existence of everything created.  He is inclined to give every play a fair show, will sit patiently through a lot of straining for effect, if there is a raison d’etre in the summing up, but his mode of thought, and it belongs to the constitution of the race, is that of getting at some truth by venturesome experiment or logical demonstration."[13]

[Footnote 13:  Louis Reeves Harrison, in The Moving Picture World.]

Bear that truth in mind, no matter what you write of, and never start anything that you can’t finish—­which is simply one way of saying, do not start to write a story at all until you have every scene, situation, and incident, so thoroughly planned, motivated and developed in your mind that when you come to write it out in action in the scenario you cannot help making the audience understand the plot.  Never attempt to introduce even a single situation without a logical cause; be sure that “there’s a reason.”

“Break away from the old lines,” advises Mr. Nehls, of the American Company.  “Try to write scenarios that will hold the interest with a not too obvious ending, with sudden, unexpected changes in the trend of the story.”

If the story contains a mystery, do not allow the end to be guessed too soon.  Interest thrives on suspense and on expectation.  The surprising thing, yet the natural ending, swiftly brought about, marks the climax of a good photoplay plot.  Many a promising photoplay script has failed because it did not make good its prophecy.  The plot opened well, but “petered out”—­the complication was a good one, but the unfolding of the mystery, the result of the struggle, the aftermath of the choice, were disappointing.

And one final word in this connection:  The photoplay public loves a “happy ending”—­unless it must be forced.

3.  The Study of Plot-Structure