Imagine three actors in search of a script, and you have a good idea of where it's at in the Mideast these days. There is an abundance of speech and not a little offstage noise and some expectant rustling among many audiences. But the action now is leading nowhere except (and I'm not kidding) toward the supreme dream of players on the world stage - the Nobel Peace Prize.

The most accomplished of the actors by far is the Egyptian, who once in fact trod the boards for a living. When it comes to showmanship, histrionics and flair for the dramatic, President Anwar Sadat outdoes Brando conceived by Cecil B. DeMille.

He initiated the present phase with the electrifying trip to Jerusalem. He followed that by meeting Prime Minister Menachem Begin at Ismailia. Then came a sheer piece of stagecraft - a break in the negotiations for no apparent reason. That set up another superb scene - a visit to Washington and the charming of President Carter, the Congress and the American public.

But Sadat lacks a sense of strategy, a feel for how to move from actions to objectives. In his speech to the National Press Club here he actually declared that he had gone to Jerusalem not to negotiate but to make peace - as if settlement was something that would happen, like the falling of the walls of Jericho, after a trumpet had sounded. So the net effect of Sadat's action was to put the making of a settlement in the hands of Jimmy Carter.

Prime Minister Begin had himself tended in the same direction. To be sure, where Sadat is heavily showbiz, Begin casts himself as a figure in a history play. He is the believing Jew who has left the ghetto and its cringing for favors. As a Zionist in prewar Poland and as an underground figure in the Palestine of the British mandate, he was a fighter. As an opposition leader, he was the outspoken exponent of an Israel that included the territories on the west bank of the Jordan River - Judea and Samaria.

His response to Sadat's overture was positive. He received him with great dignity. The offer he made at Ismailia was - by Begin's standards at least - an act of statesmanlike generosity. He not only relinquished to Egypt all Israeli claims to the Sinai Desert; he also made, regarding the west bank of the Jordan, what seemed to him a noble act of renunciation. He suspended for an indefinite period Israel's claim to sovereignty over the west bank. That, in effect, meant forever and, in time, an Arab state with links to Jordan.

But Begin also didn't know how to move from grand gesture to settlement. To dramatize his noblesse, he also turned to Washington, thus making Carter the arbiter of the whole drama.

I do not find Carter easy to understand, and for a long time I have Pondered the picture he has in his head of a settlement on the Mideast. I have come to the conclusion that what he sees is a small room where he, Sadat and Begin sit together smiling, shaking hands, making nice speeches and eventually - with suitable flourishes - setting their signatures to a document labeled Peace.

In any case, that is how he has behaved. He first said publicly that the Begin offer was a good beginning. When Sadat objected on his visit to Washington, Carter also objected, embracing Egyptian demand that Israel had to yield territory on the west bank and abandon settlements in Sinai.

To break the deadlock Carter resorted to another stage device - an emissary with the mission of drawing up a statement of mutually acceptable principles. When that failed, the president went through the public act to turning a cold shoulder to Begin in Washington early last month. But when Begin came back last week, there were smiles and songs in the Rose Garden and the appearance of harmony and progress.

In fact, there is no road map for getting from here to a settlement. Israeli Foreign Minister Moshe Dayan, in a television interview with Barbara Walters the other day, voiced in agonizing terms the need to move from abstract talk about "the wording" of principles to "concrete proposals . . . on the ground and in reality."

Fortunately, there is still time. Though Sadat has very little support in his own country or the rest of the Arab world for continuing his peace initiative, he is still hanging in there - "flying solo," as one Egyptian put it in Cairo not long ago. A main reason is that he wants the peace initiative to be still alive when the Nobel Prize is voted in October. So at least there are a few more months for somebody - presumably Secretary of State Cyrus Vance and Dayan - to come up with a script that will bring the three leading actors to the semi-happy ending that is at least still possible.