At first glance it looks like a travel poster for Albania. But the ambiguous image of emotional embrace unveiled in full-page ads last week is in fact the herald of the most mysterious movie of the holiday season -- Warren Beatty's $33.5-million epic of revolution and love titled simply "Reds."

"Reds" is the Dr. Zhivago-scale love story of John Reed, an American journalist who covered the Russian Revolution and wound up joining it, and his ambitious and free-spirited wife, Louise Bryant. The finished film is three hours and 19 minutes long, and has been the pet project of Beatty's for more than 10 years. His co-star is Diane Keaton and the cast includes Jack Nicholson, Gene Hackman, Maureen Stapleton and Jerzy Kosinski.

It opens Friday in 400 theaters around the country, including Washington, and in another 450 theaters by mid-month. To make a profit, it will have to be what is called "a genuine movie-going experience" -- yet most critics have not yet written a word, there has been virtually no advance publicity, and exhibitors first saw it only last week.

The best kept secret in Hollywood today is why is "Reds" the best kept secret in Hollywood today?

"I just don't know if I can talk about it," said Gordon Weaver, the marketing hotshot at Paramount Pictures who led that studio's year-long trumpeting of "King Kong" in 1976 and dreamed up the "Warren with wings" ad image for Beatty's last picture, "Heaven Can Wait."

"Can I make a phone call and call you back?" Weaver said. Weaver's job is to get people talking about Paramount's movies. He called back to say "our policy is going to be to not talk about the marketing of 'Reds.' "

The advertising poster was photographed by Stanley Tretick of Washington, a veteran movie-stills man. He was on the "Reds" set for a month in England and Spain, but he doesn't know if he should talk about it.

"Warren likes to play everything close to the vest," Tretick explained. But he does know that Warren chose that photograph himself out of the 120 rolls of film Tretick shot. "Yes, his assistant called me up and described that picture exactly. Obviously they see it as a love story. Warren always approves things like that."

Whatever the question is about "Reds," the answer apparently is Warren Beatty, Hollywood's most bankable star. In 21 years and 16 films he has yet to have a flop, and as a producer he has a perfect batting average with "Bonnie and Clyde," "Shampoo" and "Heaven Can Wait," each of which has done well at the box office.

He has won the right to make any movie he wants to, the way he wants to, and his choice has been the story of John Reed. He wrote, directed and produced it.

Reed, after covering the Russian Revolution of Nov. 7, 1917, wrote a book titled "Ten Days That Shook the World," an observer's account of the Bolshevik takeover that Lenin himself endorsed as "a truthful and most vivid exposition."

Reed returned to the United States after the revolution to help found what became the American Communist Party, then returned to the Soviet Union where he died of typhus in 1924. He is buried in Red Square in a hero's grave and is commemorated by a plaque in the Kremlin wall.

The story begins in Portland, Ore., at the beginning of World War I. Reed is an adventuresome reporter in conflict with middle-class American values. He is already famous when he meets Louise Bryant, who is married to a dentist but trying to paint and write. She abandons her husband to go to New York with Reed, and the kindred spirits take up residence in Greenwich Village where their circle of friends includes the playwright Eugene O'Neill (Nicholson), the socialist Emma Goldman (Stapleton), and editor and writer Max Eastman (Edward Herrmann).

The scene changes to Provincetown on Cape Cod, where O'Neill is trying out some plays and where he and Bryant have an affair while Reed is off reporting elsewhere. Soon thereafter Bryant and Reed get married, but again their paths separate as he goes off to Russia and she to cover the war in Europe. Separately they endure many hardships.

By the end of the film Reed has been imprisoned in Finland and found himself deeply involved as a participant in the aftermath of the Nov. 7 revolution that his own best-selling book had reported to the world.

The "Reds" canvas is a vast one, and since Reed died at the age of 33, Bryant by his side, it has a natural and inevitable conclusion.

Beatty was first drawn to the Reed story during a private trip to Russia in the late 1960s, and wrote a first draft nearly 10 years ago. Subsequently he interviewed many contemporaries of Reed, among them writers Henry Miller and Will Durant, statesman Hamilton Fish, Roger Baldwin of the ACLU (who was a neighbor) and Dora Russell, widow of the philosopher Bertrand Russell. These interviews were later cut into the film itself to provide contemporary perspectives on Reed as idealist, free-lover, communist and man.

From the beginning, however, the material seemed to raise difficult questions for the movie business. First of all was Reed himself. There is no question that he has a place in history all his own. The question is whether for Americans it was the wrong place.

"The thing about Warren is that he's a compulsive worker," Stanley Tretick was saying. "When he took me on as special photographer he gave me free range to cover the movie as if it were a news event. But he was also playing his cards close to his vest."

Tretick has photographed many large-scale films, including "The Candidate," "Heaven's Gate," "Urban Cowboy," "The Electric Horseman" and the forthcoming Keaton vehicle "Shoot the Moon." "Shoot the Moon" has now been put off until 1982, reportedly so that Keaton will not risk competing with herself at Academy Award time.

"When I'm working with Redford, he'll always show you the dailies or rushes," Tretick said. "With Warren you don't expect that. He's more private, even though he's working with you 18 to 20 hours a day. There's no question he is the man in control."

If Paramount Pictures has been uncharacteristically silent about "Reds," there has been no lack of long-distance speculation in other studios and the film community in general.

The early rumors -- that the film was such a disaster that it would never be released, that Beatty had gotten fat, that the budget had gone through the roof -- have now been laid to rest. The star is in fact trim, the film is opening, and Paramount is sticking by its $33.5-million figure.

But the silence, the mystery, remains.

"To understand what's going on here," said one film executive who asked not to be identified, "you have to know how Warren works.

"The problem, or let's say the situation, at Paramount is that Warren has a tremendous amount to say about everything and he has the support of Barry Diller, the president, when he says it. Everyone below that level is pretty well sandbagged from the beginning.

"Warren has a hard time making up his mind about things. That includes an ad campaign, and it includes making a movie. He's a perfectionist, even a megalomaniac, although I wouldn't say he's arrogant about it. He's just won the right to have things his way.

"The danger for Paramount was in being perceived as another 'Heaven's Gate,' in which the studio loses control. And I can tell you, there has been great concern at Paramount, even up at the Gulf + Western Corp., about the whole thing. The title, the subject matter. The fact is there was no production supervisor on the set for a while.

"I would say this whole thing is being seen as Barry Diller's baby. If it goes, he'll be the hero of all time, and if it doesn't, he'll be the goat of goats.

"But it won't be terminal for anybody, because Paramount has been selling off pieces of the movie all along, I'm sure. You know, to protect the down side just in case. You can bet they're protecting the down side on this one."

Aside from the political challenges of "Reds," both in its story and its sale, there are practical considerations that increase the stakes.

Although the public hardly knows the movie exists, "Reds" is going to have to get off the starting line fast to survive during the holiday competition which includes "Ragtime," Henry Fonda in "On Golden Pond" and a host of lesser competitors such as Burt Reynolds' "Sharkey's Machine"; the giggly Andy Kaufman and Bernadette Peters vehicle, "Heartbeeps"; or Steve Martin's "Pennies From Heaven."

As one observer put it in the jargon of the movie industry: "Once this would have been a hard-ticket movie in a downtown gingerbread house. Now you've got Zhivago on 900 screens."

Translation: Such films were formerly given their starts with exclusive runs in big-city houses, where they made their reputations and drew critical attention. Then after a few months they went into "platform release," with exclusive engagements in perhaps a dozen smaller cities. Later still, more cities were added; and only when exhibitors were clamoring for the product nationwide was it released to neighborhood theaters everywhere.

"When you go into all the theaters at once, you're betting on it being one of those true motion picture events everybody hopes for. It has to sell out, because with a movie this long the exhibitor is only going to get one showing per night."

There is another more cynical explanation for why Paramount has said so little about "Reds" and why it is being released almost simultaneously. If a movie is going to get bad reviews, the idea is to get everybody to see it at once before the word gets out.

At the moment "Reds" remains a fascinating mystery.

Gordon Weaver of Paramount declined to characterize the situation as either desirable, undesirable or other. "The only mystery about this is that we aren't saying anything," he chuckled.