Never mind the color thing. Playing the demon barber of Fleet Street is a stretch for any actor, one that requires extended forays to the dark side where obsession and enmity reside.

You've got to think mean. Real mean. Relegate your smile to the dustbin. Watching a lot of grim footage from the civil rights movement helps stoke the rage. So does snarling.

Sweeney Todd just isn't sunny. And Norm Lewis, the star of Signature Theatre's production of Stephen Sondheim's murderously melodic musical--and possibly the first African American professional to take on the role--is nothing if not sunny.

"I usually play roles that are charming," says Lewis, 36, who last appeared on Broadway in "Side Show," where he originated the role of Jake to critical acclaim.

"I'm trying to strip all that away. Mostly I'm trying not to smile, because then I just lose it."

Stripping away the charm, boiling down the sweetness until nothing is left but bitter residue, took some major deprogramming on Lewis's part. To that end, he watched old documentaries of Jim Crow-era protesters. Took in the dogs and the water hoses used as weapons against black men, women and children. And he got mad. Real mad.

But that wasn't enough. And so, there were the endless heart-to-hearts with Signature Theatre Artistic Director Eric Schaeffer, who poked and prodded, prodded and poked until nice Norm got in touch with his own inner demon.

"He's such a warm guy," Schaeffer says. "I think the last thing he wants is for people not to like him. I told him, 'Norm, you just have to go there.' It's hard for anybody when you have to go somewhere you don't normally go. Once you're there the performance can be so riveting--because it's so dangerous."

Traditionally, Sweeney Todd, the throat-slashing barber who makes a sport out of cannibalism after his wife and daughter meet with tragedy, is played as high camp, a wink-wink, nudge-nudge approach to murder and mayhem. Lewis's Sweeney Todd, on the other hand, is a big, brooding presence, evoking images of a mournful Othello unable to shake an obsessive love--and an equally obsessive urge for revenge.

"Sweeney was a normal nice guy who had a synaptic breakdown and went to that dark place," Lewis says. "I don't want people to like him. But I want people to see him as someone with purpose, someone who really believed what he was doing was right."

For his part, Lewis didn't stride with purpose into musical theater as much as he meandered into it. Talent, hard work and a laissez-faire approach to show biz kept him in steady work, from guest stints on "The Cosby Show" to commercials to a regular gig as Assistant DA Keith McLean on "All My Children" to Broadway roles in "Miss Saigon," "The Who's Tommy" and "Side Show."

With "Side Show," which debuted on Broadway in 1997, New York's theater critics took notice of Lewis's powerful performance, with the New York Times roundly praising his "big baritone and stage presence."

The big baritone was something that Lewis didn't give much thought to at first. Growing up in Eatonville, Fla., the nation's oldest chartered black municipality and the childhood home of Zora Neale Hurston, singing was just something Lewis did.

If you were the grandson of a preacher, your weekly presence in church was pretty much a given. And once you're a regular church fixture, it pretty much follows that you're going to don robes and hang out with the choir every Sunday, too. Which Lewis did, starting at the age of 10.

But even with those years in the church choir, it wasn't until Lewis hit 17 that it dawned on him that maybe there was something to this singing thing after all. This discovery happened almost by accident: Lewis wandered into high school choir as a way to get out of home ec. There, he sampled Verdi and Bach and found all that swooping and soaring over the labyrinthine layering of notes absolutely delicious.

"In gospel, you do a lot of screaming and stay on the same note," Lewis explains. "With the classics, I loved the intricacies of the music."

Even so, Lewis didn't take either music or theater seriously. Instead, after graduating from high school, he enrolled in a community college, majoring in economics. Music was never very far away. He stayed in singing shape, performing in local talent shows. The talent shows led to a short-term stint on a cruise ship. Performing enchanted him, so in 1989 he headed for New York. Almost immediately, he found work in regional theater and international touring companies. Five years ago he advanced to Broadway.

"I made it fun," Lewis says. "I didn't see it as a desperation thing. If I didn't make it, I could always do something else."

He took the same approach to the auditions for "Sweeney Todd." Sweeney was a role that always seemed beyond his grasp; Lewis figured he'd never get a chance to play the murderous barber--unless he owned his own theater and could afford the luxury of casting himself.

And so, even though this was a role that he really, really wanted, he pretended that he was engaged in an acting exercise. It worked.

"When we were casting for 'Sweeney,' I didn't find what I wanted here," Schaeffer says. "So I told the casting director, 'A Norm Lewis would be terrific.' "

The Arlington theater got the real thing. And was a little shocked to see that Lewis was willing to work at the Signature pay scale: $246.60 a week.

"When I heard that Norm wanted to play Sweeney, I said, 'Does he know how much we pay?' " Managing Director Paul Gamble says.

The pay didn't matter so much as the chance to seize a meaty role that wasn't saddled with the imprint of race.

"I thought it would be good to set a precedent for roles that are universal and don't really deal with race," Lewis says. "I love the 'Ain't Misbehavin's' and the 'Dreamgirls.' But I don't want to be limited. So many African American actors go to schools, to expensive schools, to study Shakespeare. We shouldn't be limited. So I petition for roles. That's my way of fighting."