A black stretch limo waits outside a nondescript row house in lower Manhattan. Inside the house, up two flights of uneven stairs, in a cramped room toward the back, Mariah Carey works furiously to finish editing a new video before she leaves for a European promotional tour.

But this isn't the Mariah Carey we're used to seeing. There are no cutoff denim shorts or midriff-baring tops. Not too much makeup. On this particular evening, Carey doesn't seem much like a pop music superstar, just a very tired woman working hard to ensure that her new album, "Rainbow," is a hit.

Before the night is over, Carey will supervise the editing of this video, make editing suggestions for another video over the phone, work on the remix of her next single, "Thank God I Found You," at a Times Square studio, attend a meeting at NBC's "Saturday Night Live" studio and then return to the Times Square studio to finish the remix before going home to sleep. "I've had about three hours of sleep," she says. "I've been consistently sleepless since I started promoting this album, and I'm really exhausted."

Carey, 29, has already had more No. 1 pop singles than any female artist in history. She has spent more weeks at No. 1 than the Beatles. So why is she pushing herself so hard?

For most of Carey's decade-long career, she was a pop music Cinderella, the singing-songwriting girl next door who married a record industry mogul--Sony executive Tommy Mottola--and went on to score a string of pop mega-hits. But in 1997, her fairy tale took a real-life turn when she divorced Mottola. The lyrics on her "Butterfly" album released that year suggested Carey's personal and professional struggle with Mottola, who has emerged in news accounts as a controlling Svengali with a vise grip on every aspect of her life and career. "Butterfly" sold 4 million copies, an impressive figure but far short of the 11 million sold by her previous album, "Daydream."

As Chairman and CEO of Sony Music, Mottola still ostensibly oversees Carey's career; she records for Columbia Records, a Sony subsidiary. Carey is convinced that Sony did not promote "Butterfly" as well as it should have. " 'Butterfly' was a very subtle record that I will always stand by and love," she says. "But unfortunately there were only two singles commercially released from that album, and they were seven months apart."

There is further evidence that Columbia may not be looking after Carey the way it once would have. Earlier this year, the label released the track "How to Rob" by new rapper 50 Cent, in which he fantasizes about a violent attack on Carey: "I'll manhandle Mariah/Like, [expletive], get on the ground/You ain't with Tommy no more/Who gonna protect you now?" It's hard to imagine another label allowing a new artist to attack one of its top stars so viciously.

All of this explains why Carey is taking her career into her own hands. And why, after selling 115 million singles and albums, she's still pushing herself like a rookie with something to prove.

"I feel like I have to keep going," she says. "Probably because I'm insecure and I feel like I have to maintain how far I've come."

When Carey first skyrocketed to fame in the early '90s, she was always surrounded by her husband and other top-level record company executives. "Everybody was so nervous and uptight," she says.

It wasn't until she began meeting other artists her own age that she realized how unhappy she was. "I would think, 'Why do I have to be so miserable?' I felt like I wasn't as free or as happy as they were because I wasn't living my own life."

Hip-Hop Trespasser

It didn't help that "Butterfly" seemed to coincide with a kind of Mariah backlash.

The album included collaborations with Puff Daddy, Q-Tip, Missy "Misdemeanor" Elliott and Bone Thugs-N-Harmony. And suddenly, Carey was being accused of being an opportunistic and inauthentic trespasser in the hip-hop nation. The charge came from critics and rappers, and even from comedian Sandra Bernhard, who performed a scathing routine about Carey's shift in musical direction.

"People said, 'She did ballads and then suddenly she did 'Butterfly' and became like this hip-hop girl,' " Carey says.

But Carey's work has long had hip-hop and R&B elements. Her debut single, "Vision of Love," went to No. 1 on the R&B chart before topping the pop chart as well. Her '93 hit "Dreamlover" was based on the same musical sample that rapper Big Daddy Kane used for his hit, "Ain't No Half Steppin.' " In '95, Carey worked with Puff Daddy on a "Fantasy" remix, which featured the Wu Tang Clan's Ol' Dirty Bastard rapping the memorable line: "Me and Mariah go back like babies and pacifiers."

"Anyone who heard 'Fantasy' in 1995 with Ol' Dirty Bastard knew that's what I was into," says Carey. "I was a Wu Tang fan."

The criticisms echoed the flak she got at the start of her career, allegations that she was, as Carey puts it, "another white girl trying to sound black."

"It's the same drama I've dealt with my whole life," she says. "I think that a lot of it has to do with me being visually perceived as white by a lot of people who don't understand about mixed-race people. And that's been a gripe of mine for a long time."

Ironically, once it came out in the press that Carey was not white, but the child of an Irish mother and a father who was of African American and Hispanic descent, music critics griped that she was trying to downplay her ethnic roots, a charge she's still defensive about. "What did they want?" she asks now. "A sticker on the album cover? I've always said that my father is half black and half Venezuelan and my mother is Irish. But people don't understand. . . . They can't fathom that I'm African American, Venezuelan and Irish."

Did Sony initially present Carey as a white artist in a misguided attempt to make her more marketable to mainstream audiences?

Maybe.

"When you're dealing within a corporate structure, and you're basically a teenage girl starting out, surrounded by a lot of powerful people, you're not at the helm of how you are perceived," she says. She claims that her mainstream pop image was carefully shaped. "There were songs that didn't even get to my first album because I was told they were 'too urban,' " she says. And after the No. 1 R&B success of her debut single, Carey says, "I know that there was a conscious decision to go more pop after that. Back then, people were, like, 'Write us a big ballad where you're singing really long notes.' And I know how to do that. It might not be the most stimulating thing for me creatively, but I know how to do it."

An Insecure Streak

Carey was raised in Long Island, and because her parents had divorced, she and her mother moved frequently from one town to another. Being raised as the child of a divorced interracial couple was especially difficult, says Carey, explaining that she grew up "with a lot of disturbing imagery around me, a lot of stuff that most kids in suburbia did not see."

"I grew up very fast in terms of my perception of the world and my understanding of what it's like to be mixed," she says. "I know what it's like to hear how white people speak about black people when they're not in the room and vice versa."

This kind of awareness impacted her self-esteem. "I felt like, if my mother's family disowned my mom because of this, what does that make me?"

It's hardly surprising that Carey wants her music to be embraced by both white and black audiences. It offers her the sort of acceptance and belonging that she's longed for during much of her life. In the liner notes to the new "Rainbow" album, she offers these words: "In a perfect world, human beings would coexist harmoniously, like a rainbow, a multitude of colors . . . "

The new album is Carey's most confident blend of her pop and R&B callings, primarily because she works so much and so well with producers Jimmy Jam and Terry Lewis. "Rainbow" includes the moving Jam-and-Lewis-produced pop ballad "Can't Take That Away (Mariah's Theme)." On that track, says Jam, Carey gives "her best vocal since 'Vision of Love.' " The album also includes the sensuous Minnie Ripperton-inspired "Bliss," which Jam and Lewis wrote with Carey specifically to spotlight her distinctive high notes, which have been relegated to the background on recent albums after critics railed against the "vocal gymnastics" in her early work.

As the producers behind hits by Janet Jackson, Boyz II Men and, most recently, Chante Moore and Jordan Knight, Jam and Lewis have perfected the craft behind making R&B songs go pop and grounding pop songs in rooted R&B traditions.

"We have R&B sensibilities because that's our love, but we also have pop sensibilities because we grew up in Minnesota, where, at the time we were growing up, there really was no black radio. Mariah's very much the same way," says Jam. "She has an appreciation for pop music, but she also has a love for R&B. And a lot of her influences are R&B."

"I don't listen to pop radio," says Carey. She fiddles with the radio in her limo, switching the station to New York's rap-heavy Hot 97. "I can tell you more about Jay Z's album than whatever-pop-group-you-want-to-name's album."

In fact, Jay-Z raps on "Heartbreaker," and Carey will return the favor on the first single from his new album. Is Carey now accepted--and credible--within the hip-hop community? Since the sales of hip-hop artists largely depend on maintaining their credibility in the streets, it's unlikely that Carey's hip-hop collaborators would work with her if they felt she would threaten their image. The rappers who guest on "Rainbow" include Snoop Dogg on the slinky "Crybaby" and Master P on the rousing "Did I Do That?," based on a sample of Silkk the Shocker's "It Ain't My Fault."

As did "Butterfly," the new album addresses Carey's marriage to Mottola. On the song "Petals," she sings, "I gravitated toward a patriarch so young, predictably/I was resigned to live my life within a maze of misery."

"I was really miserable for a long time," she explains. "I just wanted to enjoy my life a little bit."

Carey's friends and colleagues confirm that she is much happier now. "I can show you pictures where you can see the difference between when she had her 'force field' around her and another case where she wasn't part of that entourage anymore," says David Morales, the producer who often works with Carey on her dance club remixes. "It's such a big difference. She's much more relaxed. You can see the light in her eyes. You can feel that she's having fun. I guess it's because she has more control over what she's doing and not feeling like a prisoner."

Now Carey is not wedded to a record company executive. She is married to her job. "I have an overblown insecure streak that runs through me. And sometimes it manifests itself as me being a workaholic. I just work, and I think it's because in the early part of my life, I felt like I had to always scramble. And I didn't know whether I had any stability or what was going on in my life. And then I got into that relationship and I had this success, but I never really felt that euphoric fame feeling, that initial sensation of feeling famous," she says.

These days within the industry, when people talk about Mariah Carey, they talk about her exhausting work habits. Jimmy Jam says that during the recording of "Rainbow," he and Lewis would have to "kick her out" of the studio. "It was that kind of craziness," he says.

At NBC's Studio 8H, the famous "Saturday Night Live" studio, Carey's manager, Louise McNally, watches her rush out of a meeting so that she can return to the recording studio. "In this business," McNally says, "some people need to learn how to work and other people need to learn how to relax."

For the time being, Mariah Carey doesn't have time to relax.