"A friend of mine came over to dinner one night," recalls playwright David Henry Hwang, "and he said, 'Have you heard about this story about this French diplomat who fell in love with a Chinese actress who turned out to be a man?'

"And I thought, well that's interesting. I bet I could do something with that."

And so, from a crumb of after-dinner gossip, emerged the new play "M. Butterfly" and with it a new Broadway writer.

Opening tonight at the National Theatre before going on to New York's Eugene O'Neill Theatre, the production features actor John Lithgow, the direction of John Dexter ("Equus"), sets and costumes by designer Eiko Ishioka, Japan's foremost art director, and new age composer Lucia Hwong -- a marshaling of resources almost unheard of for a new play.

Not bad for a playwright who's all of 30 years old.

But then, Hwang's not exactly green, either -- his first play was produced at the New York Shakespeare Festival, and he's written many since. Sitting in an office above the National a week before his latest tries its wings, he talks excitedly about the birth of the play, his rapid, wide-ranging speech perhaps a product of his years as a Los Angeles high school debate champ.

The "Butterfly" Case: "There was a French diplomat who had been stationed in China in the early '60s, and he fell in love with a Chinese opera actress and they had an affair that lasted 20 years. She even presented him with a child. But she turned out to be a spy, so he was passing on information to her that she was passing on to the government. But the strange part is that they were arrested in France in '83 and charged with treason and over the course of the trial it came out that the Chinese actress was actually a man who dressed as a woman. And this Frenchman even today, in jail, the real guy, still claims that this is a woman.

"So the play is about, well, how can this be, and what does this mean," Hwang says. "For instance, I thought it was interesting to have a middle-aged man meet a Chinese woman in the Orient and fall in love with her as part of sort of a midlife crisis, and part of a way of relooking at himself. He perceives it to kind of be his last chance to meet a beautiful woman and have this affair."

The real-life events dovetailed nicely with the plot of Puccini's "Madame Butterfly," portions of which are used to underscore the play. "The fact that this incident could actually occur demonstrates the way that the West misperceives the East, that men misperceive women," Hwang says. "If somebody who wants to believe something -- that is, that the most beautiful Oriental woman in the world has fallen in love with them -- if they are in a position to have someone agree with them, they will choose the fantasy over the reality.

"And 'Madame Butterfly,' the opera, was an interesting way for me to go at that. Because at the beginning of the play, the Frenchman sees himself as Pinkerton -- he's found this beautiful Madame Butterfly in China. And by the end of the play he kind of realizes that it is he, the Frenchman, that has been sacrificed for love, that the spy was actually the Pinkerton who preyed on his love. So I thought it was a nice axis to turn that whole story on."

It's relatively rare in these days of lavishly produced British musicals that a new, untried American play goes directly to Broadway without a series of regional tryouts.

"I think Stuart {Ostrow, coproducer with David Geffen} is just very brave," Hwang says. "Sometimes he refers to himself as a kamikaze producer, in the sense that he's willing to take the kind of risks that a lot of people in the commercial theater make noises about taking, but aren't actually willing to put their money where their mouth is."

"It was a very easy decision," avers Ostrow, whose two biggest Broadway successes, "Pippin" and "1776," also made their out-of-town debuts in Washington. "I read it a year ago, and I thought it belonged on Broadway because of its inventiveness and the quality of the writing. In an age of what I call 'first-draft writers,' David stands out as a generous and hard-working artist. I think he's going to be a very important American playwright."

Ostrow had worked with Hwang and composer Philip Glass on another project, a musical theater adaptation of Andre Malraux's "La Condition Humaine." But when production rights stalled the show, Ostrow asked Hwang for something else. " 'M. Butterfly' was originally intended to be a musical," Ostrow says. "We were both fascinated by the newspaper stories, and I commissioned David to write it. And some time later he came to me and said, 'Stuart, this is a play.' And he was right, of course. I'm happy that we still get the music in there, though."

Hwang had his first play, "F.O.B." -- which stands for "Fresh Off the Boat" -- produced by Joseph Papp for the New York Shakespeare Festival. He was 22, and it won an Obie, off-Broadway's equivalent of a Tony Award, for Best Play of 1981. Papp went on to produce five of Hwang's plays.

"It was definitely a nice way to get started," Hwang says with considerable understatement. "It was a little intimidating, but one of the great things about being 22 is you really have nothing to lose, you know? The very fact that this production existed was more than I could expect to hope for at that age."

"Fundamentally he writes well," says Papp, "and I found it interesting that he is always in the middle of trying to find his roots and work in an American style. Each of his plays became richer and more complex as he became more conscious of his life in the theater."

That life includes "Rich Relations," "The House of Sleeping Beauties," "The Dance and the Railroad," about Chinese railroad workers in the 1860s, and "Family Devotions," which Hwang describes as "a Kaufman and Hart type farce about a wealthy Chinese-American family living in the suburb of Bel Air in Los Angeles and what happens when they're visited by their long-lost uncle from the People's Republic of China."

Hwang's insight into East-West relations comes from the fact that he has a foot in both worlds. And his family history has served as an inspiration and as a connecting thread that runs through his plays. His father is from Shanghai, his mother is from the Philippines -- and Hwang was born in Los Angeles, where he lives with wife Ophelia, an art student and a Canadian of Chinese descent.

"It was very important for my parents that they let us feel that our horizons in this country were fairly unlimited. As the child of immigrants, you realize there are a lot of opportunities, and there is also a certain amount of racism you have to deal with and all that. But I read someplace that because your parents did it, you really feel you can do anything."

Hwang says his father was wary at first of the idea of his son becoming a writer. "When I was doing 'F.O.B' at Stanford {University} in the dorm, he decided to come up and see it, and he said to my mother, 'Well, you know we have to see this and we'll decide whether this is good or bad, and if it's bad we have to discourage him from doing this.' And he saw it and really liked it -- my father's very emotional, so he cried and everything. My father's a bit of a ham, so I think that vicariously he gets a kick out of kids that are in show biz, so to speak. Obviously the financial prospects are a little tenuous, so he would have preferred, I think, for me to at least be a lawyer or something.

"A lot of the immigrant monologues in 'F.O.B.' are obviously things I heard at home," Hwang says. "It was sort of a thrill for my father to see some of his own life material used in this stage presentation. It could be touchy, but he has really thick skin. I've used some really awful family stories, and I think he's more of the theory that as long as they write about you ...

"For instance, he was kidnaped a couple years ago and held for ransom and all that, and so I used some of that material in a humorous way in 'Family Devotions.' There's a character based on my father that keeps telling everybody to write a movie about his kidnaping. He's been trying to get me to write the movie for a long time."

Once "M. Butterfly" is aloft, Hwang will go back to working with Glass and designer Jerome Sirlin on a musical theater piece about UFO abductions, which is due at Philadelphia's New Music Theatre Festival next September.

"To me one of the fun things about writing, particularly for the stage, is that I don't necessarily know where I'm going when I'm writing a play. By the nature of film or television I have to be a little more premeditated, but for the stage, I get the whole canvas, so to speak. So the fun for me is feeling like an audience member, watching the way it turns out as I write it.

"But I don't think I can write about just anything," Hwang says. Which should be reassuring to a lot of other playwrights out there.