The dancing extravaganza "42nd Street," which opens tonight at the Fulton, got its start as a film in the darkest depths of the Depression in 1933.

It was a movie that let you leave your troubles at the door.

Times might not be quite so dire today, but everyone would be happy to forget their woes and slip into a tap-dancing dream, wouldn't they?

"It's a happy show," says Marc Robin, who is directing and choreographing the show. "We need that right now."

When Robin saw it close to 30 years ago in its original run on Broadway, it made him so happy it literally changed his life.

"It was the first Broadway show I ever saw," recalls Robin, who was 18 at the time. "I watched the money number ("We're in the Money") and I thought, wow, I want to do that. I just felt this thunderous joy."

It was the dancing that got him.

"It was one thing after another coming at you," he says. "The best role in that show is being in the chorus. The joy of '42nd Street' is in the dancer's feet."

Robin, who had been acting since he was a child, suddenly shifted gears and became a dancer.

"Something just clicked. I think it was the joy of it," he says. "It was calling me, my body took to it naturally."

At 25, he got cast in the last leg of the first national tour of "42nd Street."

"I did it for a year and a half," he remembers. "It's an exhausting show. You never stop. And you get to use your entire skill set — ballet, jazz, tap."

And now Robin, who is well known to Fulton audiences for his dancing shows ("Crazy for You," "Thoroughly Modern Millie," "West Side Story") is directing it for the first time.

The story revolves around Peggy Sawyer (Meghan Garstang), who has arrived in New York City fresh off the bus from Allentown, Pa.

She's too late for the auditions but she's caught the eye of the young lead, Billy Lawlor (James Patterson), who tries to get her cast without an audition.

But the choreographer tells her to beat it and Peggy is so embarrassed, she runs out of the theater, crashing right into the director, Julian Marsh (John Reeger), who, of course, falls madly in love with her and gives her a role in the chorus.

Meanwhile, well-past-her-prime prima donna Dorothy Brock (Paula Scrofano, who is Reeger's real life wife) is upset that she's been asked to audition for the lead. She gets cast only because her sugar daddy, Abner Dillon (Douglas E. Stark), agrees to finance the show.

When Peggy crashes into Dorothy on opening night (She does a lot of crashing, doesn't she?) and breaks the star's ankle, she gets fired for her clumsiness. It looks like Peggy's Broadway career is over before it started. She heads back to the train station, ready to leave show biz behind and go back to Allentown.

But we know that won't happen. We know Peggy will be talked back into the show, that she'll learn the leading role in two days and knock 'em dead in her Broadway debut.

For Robin, the charm of the show is in its spirit.

"It's taking place during the Depression. People need the jobs. If you didn't dance for your life at every moment, you wouldn't get the job," he says. "It really comes from the heart."

But then, dancing always has.

He looks for that spirit when he's casting.

"We saw over 600 people for the show," he says.

The first round of auditions is fairly easy.

"This is largely a tap show, so I'm looking for cleanliness in your steps, articulation. You can either do the step or you can't. Call-backs get more difficult."

That's when personalities come into it.

"If they're not nice people, I don't want to work with them," he says. "What I don't know is how they perform, what's their personality. The style of the actor has to fit the style of the show."

And you've got to dance for your life at every moment.

"42nd Street"

Opens tonightCont. through Jan. 4

Wed. 2 and 7:30 p.m.

Thurs. 7:30 p.m.; Fri. 8 p.m.

Sat. 2 and 8 p.m.; Sun. 2 p.m.

$20-$48

Fulton Theater12 N. Prince St.

397-7425www.thefulton.org