SO you want to stage a notoriously difficult, mercilessly bleak and little known play by Henrik Ibsen, but how can you guarantee people are going to flock to it?

Well, you could always get Ralph Fiennes to be in it.

Looking like most men wished they looked, Fiennes is an engaging personality. Rarely breaking eye contact, he answers questions with great thought and conviction. He has a humility that betrays his movie star pedigree.

Fiennes is best known for a variety of movie roles, from the monstrous Goeth in Schindler's List and the tragic Almsy in The English Patient to, most recently, Christopher Marshall in cutesy rom-com Maid in Manhattan starring opposite Jennifer Lopez.

But he says he is not an actor who deliberately looks for variety in his projects such as the current production of Brand at Stratford.

"I don't take parts to show how versatile I am," said Fiennes.

"My response to Brand was a gut response. I mainly make my choices on gut instinct."

His guts have now led him to play the incredibly difficult role of Brand, a priest driven by an unwavering all-or-nothing conviction to his faith. Brand is prepared to let his loved ones die if he believes it is God's work.

"He is at face value quite an unsympathetic character, but that's too simple a judgement," said Fiennes.

"Brand is a tough nut to crack as a character because Ibsen has written a very extreme man who has a hard and often really tough and merciless commitment to his Christian faith, but I found there was a poetry and an epic quality in the play that I liked.

"Brand's brand of faith is very tough but there are moments in the play when you can be inspired by how he expresses his belief. At other times you could be repelled by it."

As well as the challenge of making Brand believable, the difficulty is heightened by the fact that the character is rarely off the stage.

This is why director Adrian Noble said he chose Fiennes for the role; because he is one of the few actors on the planet who can handle it.

"There aren't many actors who can cope with the demands of the role," said Noble.

"I have compared the part to King Lear, but it requires a younger actor to play it.

"In the end it's talent, I'm afraid."

Complicating the play further, Brand was never written by Ibsen to be performed on stage, not least because it involves the main character leading an entire community up a mountain in search of an church carved from ice.

To cope with this, Fiennes and Noble took a research trip to Norway to find Ibsen's world of mountains, valleys and fjords.

"Since we had the time to visit, we went, and I do feel it made a difference," said Fiennes.

"I feel that I hold those images in my head. There is no scenery as such in our play. The mountains are in the imaginations of the actors so to have seen it so that the image is really strong in my mind is very helpful."

Neither Noble or Fiennes believe audiences in Stratford or in the West End, where the play transfers later in the year, will be turned off by the powerful religious themes, foreign to many in this secular society.

"I'm not a practising anything, but I was brought up a Catholic and my mother was pretty devout," said Fiennes.

"Ibsen said that Brand could have been an architect or a politician or a lawyer. It is the strength of his determination which is the inspiration.

"But almost straight away in the play the audience sees Brand on stage with his mother, and then Brand with his wife and baby and these are situations they can immediately relate to."

In the end Brand represents a theatrical nexus. It has Fiennes, it has an advanced enough set to bring the play to life and it has Noble in the director's chair, bringing to the end his tenure as artistic director at the RSC with a play he has been planning for 20 years.

Brand is running at the Swan Theatre in Stratford until Saturday, May 24, before it transfers to the Theatre Royal Haymarket in the West End, from Thursday, May 29, to Saturday, August 30.

RSC box office: 08706 091100, Theatre Royal box office: 08709 013356.