It's a lovely summer day in the Rose Garden at Mellon Park, just like any other summer day except for the beehive of activity: props being built, costumes being distressed. It's all to get ready for Quantum Theatre's production of Howard Richardson's and William Berney's "Dark of the Moon," starting preview performances tonight, and it takes a lot of people to put up a show, especially outdoors.

		'Dark of the Moon' Where: Quantum Theatre at the Rose Garden, Mellon Park, Shadyside. When: Through Aug. 28; Wed.-Sun. 8 p.m. (rain days Mon.-Tues.) Tickets: $22-$26; 412-394-3353. Related article Mysteries of the 'Moon'

Quantum's artistic director, Karla Boos, has always been particularly good at gathering groups of talented people and finding unusual places for them to perform. And once she finds them, she likes to keep them around.

Of course, it may not be fair to say she "found" Rodger Henderson, since he was an instructor and she was a student at California Institute of the Arts when they met. But she did bring Henderson to Pittsburgh, and this is his fifth time directing for Quantum: First was "Polygraph," Quantum's 1996 breakthrough show, and he's been back for "Indian Ink" (which the Post-Gazette named the best show of 2002) and "Hapgood" (No. 3 in 1998).

Henderson remembers Boos as an "adventuresome and headstrong" student, adding that he appreciates that she's "straightforward and direct."

"Very few people do the kind of work that Karla does, which is creating a piece rather than re-creating it," says Henderson.

And he wouldn't agree to direct for Quantum if he felt otherwise. Retired from teaching, Henderson now makes his home in San Francisco and only signs on for projects that excite him.

"Dark of the Moon" excites him because it gives him the opportunity to direct three of his old students, not just Boos, who plays the Dark Witch, but also Cody Henderson (no relation), who plays the Witch Boy, and Kristie Dale Sanders, who plays Barbara Allen.

But besides that, when Boos first contacted him he remembered the play as one that was very popular when he was in college. He remembered little else except that it was about a witch who falls in love with a human.

Upon rereading the play, Henderson found it to be "a simple love story."

"It fascinates me what two human beings will do for what we call love," he says -- "whatever that is."

This exploration of human emotion and motivation is what he finds essential in all the pieces that appeal to him.

"That's the truth of what keeps me in theater, finding out what human behavior is all about."

"Dark of the Moon" resonates for Henderson in a particularly contemporary way. Through the process of directing it, he's found it's really about how difficult it is to accept a world that we don't know anything about. Each actor, he says, has to find his or her own way to do that.

As a director, he tries to help actors with just such challenges. Over the years, he's learned that there's no one way to do that. "Everybody works differently. It's about trying to find an inroad into the way each actor works."

Some of that insight comes from Henderson's own time as an actor. It's been about six years since he's acted, and he started his career as a choreographer, though he didn't start dancing until he was in college. This background still comes out in his passion for musical theater. He's a big fan of Stephen Sondheim and Kurt Weill.

"The whole journey," Henderson says, "has been about discovering a means of self-expression." But he wants only to direct now, saying that it fulfills his desire to make connections with other people.

He's had a lot of opportunity for that in Pittsburgh. Outdoor rehearsals pose a particular challenge to a director. People walk by and sit down on the risers to watch. They chat. They let their dogs run through.

"Not every director is as cool about letting the world in," says Boos. Henderson calls it all part of working outdoors, loves the juxtaposition of the natural world and the themes of the natural and unnatural in the play and says that Mellon Park lends itself to the play really well.

It soon becomes clear just how imposing working outdoors can be. A lot of dog walkers use that part of the park, and a friendly and rambunctious hound, followed by its very apologetic owner, interrupted an interview. Quantum originally announced there would be no Saturday performance this first weekend because there was a wedding scheduled at the park, but the wedding was canceled so the show, as they say, goes on.

Sanders takes a philosophical perspective. "Here's the reality," she explains. "You cannot control what is going to happen every single night. Even inside [the play], you can't control it, and that's what's exciting about live theater. It always has that element of the unknown."

Having been a student at Cal Arts, Sanders knows Boos and Rodger Henderson well; but this is the first time that Sanders, Boos, Cody Henderson and Rodger Henderson have all worked together.

Sanders has worked with Quantum before, playing the title role in "Anna Karenina." Her home base is New York and New Jersey, and she's most recently been working at the Goodspeed Opera House and at Vassar. Besides acting, she dances and sings.

"In Manhattan, I'm a singer who acts, and in the regional market, I'm an actor who sings," she says.

Besides wanting to work with Quantum again, Sanders jumped at the chance to be directed by Henderson.

"I've worked with somewhere between 80 and 100 directors and maybe four or five of those directors, I'd do anything to work with again. Rodger is one of those."

Sanders really appreciates that Henderson gives her so much freedom to explore her role.

"He makes you feel like you're creating something together," she says. "It's been terrifying and fabulous at the same time."

After reading "Dark of the Moon," Sanders knew her character takes a complex, emotional journey. The role is physically demanding. "I go home with wood chips in my underwear and hair every day," she laughs.

The emotional challenge is even greater. "I knew this project would push me to the limits of my comfort level," Sanders says.

There's something essential, she feels, about Barbara Allen's experience, about her desire to love and her wish to find someone to "witness her journey." Sanders plays with an idea of quantum physics, how the observer affects the thing being observed, and muses about this being Quantum Theatre.

Of course, all theater asks for a witness: the audience. The actor knows she's being watched and is affected by the mood, noise and/or feedback of the audience. "Actors feel the audience," Sanders says. "We feel them. They're part of the theater piece." Boos, Henderson and Sanders want Pittsburghers to be part of "Dark of the Moon."