How do you take your concept and expand it into a complex, multi-dimensional story that a reader will recommend, and that a producer or studio will want to buy? Try one of the following methods:

1. Have the set-up lead to a relationship for the protagonist, one that complicates the protagonist's goals.

Most screen stories do have some sort of central relationship, but in the ones that work best, this relationship evolves directly out of the premise. In other words, these two people never would or could have hooked up if not for what happens in this plot.

For example, in Working Girl, Melanie Griffith's character begins as a lowly secretary. It is only after deciding to pose as her boss that she is put in a position to meet Harrison Ford's character.

However, the two do not simply embark on a sweet, conflict-free affair. Becoming involved with Harrison Ford makes Melanie Griffith's life more difficult, for two major reasons: 1) it is Ford's company whom Griffith is playing her "con" out on. If she's exposed, it will hurt not only her but him as well, and she knows this. 2) Ford turns out to be dating Griffith's boss, the very woman Griffith is posing as, making it doubly difficult for Griffith to maintain the charade.

2. Create a reversal in the protagonist's situation.

One of the best ways to keep an audience on its toes and involved in your story is to suddenly spin the plot in a new direction. In this scenario, the set-up leads the audience to predict a certain pattern of events only to thwart their expectations as the plot suddenly shifts gears. This shift usually takes place at page 45 or 60.

In Laura, what begins as a routine murder investigation takes on a new angle when the detective played by Dana Andrews learns that the woman he thought was killed is still alive; it was a different girl who had been slain. Now the detective must not only solve the original crime, but also protect Laura from her would-be murderer.

3. Resolve the protagonist's problem halfway through, and have this resolution lead to a new goal for the protagonist.

If you sense that you are dragging out the action; if you feel that your story is too thin; or if you have a genre story that is not diverging enough from the traditional formula, try wrapping up the plot early, but in such a way that it leaves the protagonist at the opposite point from where you intend him or her to end up.

In The Lady Eve, Barbara Stanwyck and Henry Fonda are meant to end up together. In lesser hands, the entire story would have taken place on the cruise ship, where card sharp Stanwyck tries to bilk millionaire Fonda, only to fall for him. The action would have become increasingly dull and predictable as we waited for Fonda to find out the truth, dump Stanwyck, and then forgive her and reconcile with her at the end. However, writer-director Preston Sturges keeps one step ahead of the audience by having Fonda's discovery and rejection of Stanwyck take place halfway into the movie. The second half of the film then begins with the heartbroken Stanwyck embarking on a new goal: to get revenge on Fonda by wooing him in disguise and then breaking his heart.

In The Bridge on the River Kwai, William Holden achieves his goal of escaping from the POW camp early on in the movie, only to be recruited to go back in order to blow up the bridge that the prisoners have been forced to build.

4. Introduce a new element into the plot.

The easiest way to elevate your story to a higher level is to simply add an element to the plot. In order for this method not to seem contrived, the event should emerge organically from the story and not out of left field. It should also create conflict for the protagonist. A clear example of this is Gone with the Wind, where Scarlet O'Hara's romantic aspirations are complicated by the obstacles brought on by the outbreak of the Civil War.

The new element can also be character related. In The Graduate, Dustin Hoffman's affair with Anne Bancroft is made more difficult when Katherine Ross, playing Bancroft's daughter, arrives on the scene.

5. Change the genre.

This is the most difficult method, because it is essential that the transition be made carefully and slowly, so that the change in tone is inevitable rather than jarring.

In Laura, in addition to the reversal discussed above, the movie evolves from a murder mystery into a romance (although the suspense continues throughout), as Dana Andrews falls in love with Laura, first through the stories he hears from the people who knew her, and then in person when she reappears. Steel Magnolias begins as a broad Southern comedy but grows increasingly dramatic in its second half, due to the illness of the character played by Julia Roberts.

An imaginative premise will hook your readers, but in order to hold their interest, you need surprising plot and character developments. What all these strategies have in common is that they increase the conflict, by making the protagonist's life more difficult. Conflict leads to tension, and tension is what makes a story compelling. If you apply these techniques, the result will be an original, inventive, and unpredictable screenplay -- one that is much more likely to succeed in Hollywood.