It has been called a walk-through movie, a living soap opera, a voyeur's dream come true. Easily the most talked-about stage production in Los Angeles, with a top ticket price of $75, "Tamara" can also claim a distinct place in theater history.

"There is no place else in the world that this can be experienced. There is nothing else like it, anywhere," says coproducer Barrie Wexler.

In this critically applauded play -- which observes its first anniversary on Tuesday -- the audience walks through the plot set in the decidedly decadent household of Gabriele d'Annunzio, writer, lover and Italian patriot. The three-story American Legion building on Highland Avenue in Hollywood has been lavishly decorated to imitate Il Vittoriale, d'Annunzio's 1920s Italian villa. The meticulous sets (including Art Deco paintings by Tamara de Lempicka, on loan from such collectors as Barbra Streisand) are by Emmy winner Robert Checchi. Costumes are by Italian couture designer Gianfranco Ferre.

"What happens is a combination between 'Dallas' and Disneyland," says Wexler. A writer and Canadian television personality, he is coproducing "Tamara" with Moses Znaimer, who first saw the work performed nearly four years ago at the Toronto Theater Festival.

A tale of two fateful days in 1927, "Tamara" explores intrigues, love affairs and political schemes within the palazzo. The arrival of Polish artist Tamara de Lempicka is the catalyst for the flurry of tempers and passions. To uncloak the assorted mysteries, the audience must scramble from room to room -- and, frequently, from floor to floor -- following any one of the 10 cast members throughout Il Vittoriale's 13 rooms. A maximum of 125 ticket holders are permitted each evening, and comfortable shoes are advised.

The evening begins with a no-nonsense Fascist policeman issuing a passport to each member of the audience. Champagne is served. Rules are announced (by the imposing Fascist). Viewers are asked to move only on an actor's move. If an actor suddenly slams a door, the pursuit of that actor is not to continue. And spectators are not to wander off on their own.

The audience is then divided into three groups. And then the play's action begins.

Wexler calls the resulting experience "a hybrid between film and theater," explaining that "you are as close to the actors as the camera is."

Because a myriad of subplots unfolds simultaneously, what one discovers depends on the characters one chooses to follow. Those who scurry after Tamara in the balcony will watch her fend off d'Annunzio's repeated attempts at seduction. The earthy maid Emilia winds through the servants' quarters -- especially the bedrooms -- creating counterplay among a tortured valet, the Fascist policeman and a chauffeur with a mysterious past. In the oratorio "The Music Room," a beautiful former concert pianist longs for exlover d'Annunzio, while a doting composer longs only for her. Meanwhile, d'Annunzio's head housekeeper and confidant has designs on a silly young ballerina (who fails to comprehend her advances, despite a sensual body massage and a lingering kiss on the mouth).

To better sort out these relationships, friends among the audience tend to split up. An intermezzo -- featuring cheese, fruit and desserts by Ma Maison -- provides the opportunity to compare notes and characters.

The two-hour production climaxes in the central parlor where the play began, bringing everybody together (in a manner of speaking -- there are several death scenes). Ultimately, the audience is left piecing together the clues of a mystery and mulling over the many loose ends.

Those determined to make sense of the entire production can take advantage of progressive discounts for repeat visits. In fact, the play has acquired the adoring fans that accompany cult status. As one "Tamara" buff mused, "It's become 'The Return of the Jedi' of the L.A. theater scene."

As a prestige showcase, "Tamara" has also brought out the Hollywood names -- as both actors and observers. "Everyone and their dog has seen 'Tamara,' " says one cast member. "Everyone" includes Jerry Brown, Jack Nicholson, Gregory Peck, Gene Hackman and Steve Martin.

Indeed, there are humorous reports of stargazers who take to following the celebrities, rather than the play's actors, through Il Vittoriale. The cast members themselves are not immune to the famous faces in the crowd.

Original cast member Sue Giosa, who portrays the bed-hopping maid, recalls the night she sailed past a small cluster of people led by a handsome gentleman in glasses. "Using my Italian accent, I said, 'Well, you're very cute.' As I went on my way, I found myself thinking, 'Of course he's cute. He's Warren Beatty!' "

Then there was the night Joan Rivers (who has reportedly attended twice) trailed Giosa through the villa. "She was so close, I had to resist the temptation to say to her, 'Can we talk, darling?' "

In recent months, celebrities have been doing some of the talking in "Tamara." Karen Black appeared as the former concert artist. Anjelica Huston is just exiting, after appearing in the title role. And there are whisperings about other well-known names to be signed on.

"But 'Tamara' is not a star vehicle. This is a genuine ensemble piece," says Wexler, who maintains it is the challenge of the production that draws actors and audiences alike. "This is not a passive event. The audience is forced to make choices."

And the audience must work for those choices, says Giosa. "Once in a while, you get audiences that don't want to work. You can sense them saying, 'How dare you make me run up and down all those stairs?' But you know, that doesn't happen all that often. These days, maybe because of the attention 'Tamara' has been getting, most people want to feel the experience. After all, that is the point of the play."

As a form of environmental theater, "Tamara" puts the actors through a vigorous workout as well. During one performance a woman stood so close to Huston that she became caught on the actress' coat. "She stood there, kind of frozen solid, while I finished my lines," Huston says with a laugh. "Strategically, the play can get a little messy."

"When we first started out," Giosa adds, "we were a little nervous about working in that kind of proximity. The idea of people breathing down your neck, taking up your space, was scary."

Since then the cast has acquired a business-as-usual aplomb in moving audience members aside, if need be, or even cozying up with them for a sequence on a bed or settee.

The actors have also learned to contend with the occasional tipsy theatergoer ("a result of too much champagne and all those stairs," observes one cast member), spectators who "talk back" to the characters, and the occasional sleepwalker. Explains Huston, "One night, a man following me very closely kept falling asleep. I saw it happen four different times! At the end of the play he came up to me and said he had so enjoyed my performance. I said to him, 'I can't imagine you saw anything of it.' "

By venturing into bedrooms, some audience members might see more than they expected.

"I peel right down to my teddy for my love scenes," says Giosa. "I can tell the audience is shocked during those moments. They don't know what to expect, how far we'll go. It's a very voyeuristic experience -- 30 people clustered around a bed in a tiny room. It's so quiet, we can hear them breathing."

Bruce Abbott, who plays the chauffeur, has an eight-minute sequence in which he wears only a towel. (He declines to say whether he wears anything beneath the towel. "That's a professional secret," he says with a smile.) "You know when your audience is scared -- because they're all crammed in the corner. Then there are those nights I half expect someone to look over the screen as I get dressed."

When Abbott does emerge from the screen he sometimes finds his chair occupied. "So I take the arm of the chair," he says. "I lean on whatever I can to finish pulling on my boots. In this play, you have to make instant decisions. You really do. You have to get on with the story. You can't let your timing be thrown off."

Huston recalls the time she found herself playing a scene to an audience of none. "I went into this small room, and nobody came with me. But I did my monologue anyway, because I didn't want to destroy the momentum." Still, she admits, her vocal level did drop, "until I could barely hear myself."

Richie Revelli, who understudies three roles, relates a similar experience. His solitary monologue as the valet dropped in audibility until he chanced to see a lone spectator wandering the hallway. "All of a sudden, my voice was booming. I had found a audience."

Challenges to actors and audiences aside, Wexler says finding the proper building is the most difficult aspect of the production.

"You have to have something with an accessible location, with an interior geography that is appointable to the play. You have to adhere to zoning ordinances, get the proper liquor licenses . . ." With a sigh he adds, "You have to please the fire marshal as well as the audience. That's why we're restricted as to how many people can go through each night. You know, we could stage 'Tamara' in the palace of Versailles, and we would only be as big as its biggest doorway."

A New York staging is next on the Wexler-Znaimer agenda. According to Wexler, preproduction will begin in July, rehearsals are set for September (Huston is considering doing the title role), and, following two weeks of previews, the play will open in mid-October. "We haven't yet signed our lease, but I can tell you our New York location is quite delicious. And it can accommodate as many as 200 people."

Wexler and Znaimer also hope to take "Tamara" to London and Paris, and eventually to replace the Los Angeles production with yet another interactive play. "The possibilities are endless," Wexler says. "Can you imagine a play based on the board game Clue? Or an Agatha Christie mystery?

"We're in this to establish the form. Just as you go to see Second City in Chicago or Toronto for comedic improvisational theater, you'll come to us for a play like 'Tamara.' "

The form got further endorsement last month when it won six of 28 awards handed out by the L.A. Drama Critics Circle.

Taking "Tamara" to the masses, Wexler admits, is also on his mind. "Yes, we are going to do an electronic incarnation of this event," he says, revealing plans to film three different versions that will all mesh perfectly, scene by scene. "We plan to air the show in 20 different markets, on three stations simultaneously. The viewer will use his remote control to decide when to switch channels and follow another character , just as the theatergoers have to decide when to take off after another actor."

As to why audiences are rallying to this form of participatory entertainment, Wexler offers, "Well, it's a sensory experience -- and a sensual experience. I think we're finally entering the age of 'feelies.' "