It's  11 am and Sam Shepard arrives for our interview dressed like the all-American hero he has so often portrayed. Wearing jeans, a navy T-shirt and a leather jacket, his blue eyes are disguised by a pair of heavy-duty shades and he has a lit cigar for comfort. On his hand, a tattoo of a crescent is just visible. Now 62, despite his skin weathered by the elements - doubtless the result of spending much of his time farming his 400-acre ranch in Minnesota - he's still remarkably handsome. With his swept-back brown hair only just beginning to grey, he still has that rock-star swagger cultivated when he toured as a drummer with Holy Modal Rounders and had a fling with Patti Smith.

That was 35 years ago, at the time when the California-raised Shepard was beginning to establish himself as a writer, after co-authoring the script for Michelangelo Antonioni's "Zabriskie Point" and completing his early plays, "La Turista" and "The Unseen Hand." But Shepard, the so-called "playwright laureate of the West," as The New York Times dubbed him when his play "Buried Child" won a Pulitzer Prize in 1979, has spent a lifetime tackling American mythology while gradually establishing his own iconic status. Right down to the fact that he still refuses to use a computer or a fax. "I don't relate to any of that stuff," he growls. "It just left me in the dust. My kids are very good at it, so if ever I need it, I just put them on it."

If technology has passed him by, you get the impression that life itself hasn't - whether it be accompanying Bob Dylan on his 1975 Rolling Thunder tour or settling down with actress Jessica Lange, after they met on the set of 1982 film "Frances." Yet Shepard refuses to be seduced by the notion that, alongside Arthur Miller and David Mamet, his work is paramount in the pantheon of American playwrights. "If you get carried away with that in your mind, you get far away from what your real intention is," he says. "It's not possible to do good work if you're thinking about how it's been received. If you think about that then you're not focused. You have to be much simpler and close."

While his plays, such as "True West" and "A Lie of the Mind," have frequently been revived, with just three new works produced in the 1990s, it will come as no surprise to learn that his latest effort is for the screen, not the stage. That said, "Don't Come Knocking" is the first screenplay he has written since the 1994 western "Silent Tongue," which he also directed. It also marks a reunion with German director Wim Wenders; the last time the two collaborated was on the highly successful 1984 film "Paris, Texas," the story of a drifter searching for his family, which won the Palme D'Or in Cannes.

Similarly, "Don't Come Knocking" tells the tale of a father in search of a son he never knew he had. While it comes nowhere near the brilliance of "Paris, Texas," it's clear Shepard has hit a universal nerve. "It must have to do with the way things have collapsed, in terms of family - which doesn't have the same strength as it used to," he says. "I don't know why it's coming apart, but I feel that. I think there's a desperate air about it all. Part of the reason that this Right Wing thing has come back so strongly is that people do feel the loss of something, and they're trying to replace it with something rigid. The rise of the Christian Right is an attempt to bring back some strictness. The reaction has come full circle. It's very strange."

To an outsider, Shepard's life must feel like a movie - given that he lives with Lange and their two children, Hannah and Walker. Lange, who appeared in Shepard's much-maligned 1988 directorial debut "Far North," plays Howard Spence's estranged lover Doreen in "Don't Come Knocking," the first time they have appeared on screen together since 1984's "Country". Shepard admits it wasn't easy. "It's very difficult because you know each other so personally, but in the end it's worthwhile because you touch on certain things that are deep."

Ironically, you can read Howard as Shepard's own fear of movie-stardom. He began his life as an actor in earnest in 1978, when he played the farmer for Terrence Malick in "Days of Heaven." But after Philip Kaufman persuaded him to play American astronaut Chuck Yeager in "The Right Stuff" five years later, Shepard suddenly found himself thrust into the limelight as he was nominated for an Oscar for Best Supporting Actor. While he went on to appear in Robert Altman's film of his own play, "Fool For Love," Shepard admits he was nervous about his expanding profile as an actor.

"There was this feeling that my credibility as a writer would go in the toilet if I suddenly became Robert Redford," he says. "I didn't want to be a movie star. I didn't want to have this thing of being an icon. It scared the shit out of me."

Frequently cast in Hollywood as the authority figure - reminding us his dad was an officer in the Army Air Corps - this year alone, Shepard is set to star with Salma Hayek in "Bandidas" and Brad Pitt in "The Assassination of Jesse James." Yet by taking an increasing number of secondary film roles, a case can be made that, as he becomes more of a low-rent celebrity, the sheen is systematically being wiped away from his early achievements. As the myth surrounding Sam Shepard is slowly dismantled, is he as finished as Howard Spence?

Not quite. Currently planning "an old-fashioned" Western with Wenders, I suspect the curtain has yet to fall on Sam Shepard's third act.