Theatre Royal, New Road, Brighton, Monday to Saturday, May 17-22

It is the early hours of the morning in New York in 1953 and the Cold War is just getting started.

In America the anti-Communist witch hunt is at its height and a certain blonde actress, who has her name in lights and her dress blown up around her waist, calls on the most eminent scientist in the world.

With her is a prominent baseball player and a major politician who is determined to find Communists everywhere and root them out of public life.

In Insignificance, playwright Terry Johnson has presented us with four icons of the Fifties -

Marilyn Monroe, Albert Einstein, Joe DiMaggio and Senator Joseph McCarthy, and imagined them all together in a hotel room where Marilyn wants to know all about the Theory of Relativity.

It's a tough, intellectually stimulating comedy drama, an imagined journey of these four giants of the period, notably filmed by Nicholas Roeg back in the Eighties.

It is being directed by Rupert Gould, the man behind the surprise stage hit Cleo, Camping, Emmanuelle and Dick - about the relationship between Barbara Windsor and Sid James.

He describes Insignificance as "a landmark play".

He says: "It was a time when there was a pervading feeling of fear which permeated American society from top to bottom. Fifty years on western society is once again filled with the fear of a hidden enemy and civil liberties are under threat once again."

Johnson's play is now more timely than ever and it is very difficult not to draw parallels between the McCarthy era and the Bush administration.

Gould says: "Insignificance is tough comedy looking at these four iconic characters who interact in ways you would never imagine.

"Johnson, who had a smash West End hit last year with Hitchcock Blonde, is an amazing playwright.

"Most scripts you read today you know will be equally at home on stage or television. But Johnson is a theatre man from head to toe.

"His plays are intensely theatrical. They are expressly written for the stage and come fizzing into life in front of an audience."

Playing the Monroe character is Gina Bellman, star of the award-winning BBC comedy series Coupling, now entering its fourth season.

Gina, who shot to fame in Dennis Potter's TV play Blackeyes and is well known for her role in BBC's Coupling, says Insignificance is "darkly comic".

She says: "It covers a lot of ground, from the intellectual rigors of scientific theory to the nature of fame and celebrity and a hundred other matters all put into the pot.

"It is a fascinating, complex and challenging play and the stage work is much, much better than Nicholas Roeg's film which I don't think worked at all. He just didn't seem able to get a handle on it.

"I was more than a little interested in what celebrity was like for Marilyn because the nature of it has changed over the past 50 years.

"I don't believe she was the ball-breaker she was supposed to be. She had a tumultuous private life and was extremely badly behaved, particularly on the set of her films.

"But in many ways she was allowed to build up her celebrity through the big studio machines that existed in those days.

"Stories about her could be more controlled and spread out over years sometimes. The studios would employ all sorts of managers to handle the Press and go a big way towards protecting their stars from Press intrusion.

"Nowadays, in the time of 15 minutes of fame for everyone, there is no such protection. The media is bigger and more avid than ever for stories about celebrities whom they make and break.

"When I got the role in Blackeyes, the Press went wild and there was masses of coverage about me in all the tabloids. I was only 22 then and they built me up to be something I really never was.

"Nowadays, of course, as soon as the media builds you up, they try to knock you down again.

"These days I live a much quieter life. Stage actresses seem not to be so much of a target for the media. Anyway, I divide my time between here and New York, where my boyfriend lives.

"Coupling has become something of a cult hit in America, especially since the American version failed so badly last year. It is on BBC America all the time and I get recognised on the streets.

"My character, Jane, like the others, is a complex one. The comedy goes behind the funny stuff to show the vulnerabilities beneath.

"Jane is lonely and insecure and that's another element I saw when I took on the role of Marilyn Monroe.

"Marilyn was more than just a big breasted blonde. She was a complicated lady and a superb comedienne.

"I did a lot of research for the role and watched all her films so I could get the walk and the voice, although this is no impression, just an interpretation of what she was like.

"Constantly with me I have the audio soundtrack from Some Like It Hot, probably her best film. Listening to that while I get made up every evening shows just how wonderful her comic timing was.

"She gets the timing of her remarks absolutely right, there is not a beat out of step. Marilyn was far, far more than just a dumb blonde. She was a killer with a comic line."

Dark-haired Gina admits to having been uneasy about the role at first.

She says: "At first, when I donned the blonde wig and put on the dress, I felt very much an imposter and thought that any drag act could do the role.

"But the detail I absorbed about Marilyn gave me the confidence to do it. I am emphatically not Marilyn but I hope I summon up some of the essence of her."

Theatre Royal, 7.45pm, matinees on Thursday and Saturday at 2.30pm, £13 to £22, 01273 328488.