Timothy ”Timbaland” Mosley and Justin Timberlake have a secret. The duo are hanging out backstage at Miami’s American Airlines Arena on Feb. 24, killing time before another one of Timberlake’s sold-out FutureSex/LoveSounds shows. As they dig into a Cuban-themed dinner of spicy chicken and potatoes, they whisper animatedly. Then, unable to help himself, Timberlake lets it slip. ”Man,” he says, ”I gotta get my head around this 50 track.”

Unbeknownst to even their entourages, 50 Cent is at this moment in the venue’s parking lot, hiding aboard Timbaland’s tour bus/mobile recording studio, patiently waiting for an audience with the superproducer. The rapper’s presence is shrouded in absolute secrecy; even the radio-promotion men who mill about near the front of the bus have no clue that 50 is behind the steel door that separates the studio from the rest of the vehicle.

It’ll be hours before 50 gets together with Timbaland, who goes simply by Tim off stage. The most-wanted man in music has a to-do list that keeps him busy around the clock. He’s currently producing upcoming music from, among many others, Björk, Missy Elliott, and Duran Duran. He’s finishing his own new CD, Shock Value (due April 3), which features everyone from Elton John and Dr. Dre to Fall Out Boy. (The album’s so chock-full that a contribution from Jay-Z — with whom Tim has created 14 tracks — did not make the cut. More on that later.) He’s in talks to contribute tracks to Coldplay’s and Madonna’s upcoming albums (the latter with Timberlake), and this summer Rockstar Games, the company behind Grand Theft Auto, will release Tim’s beatmaking program for PlayStation 3, dubbed ”Beaterator.” Though he is only 35, Tim is such a dominant force that just about every current pop trend can be traced back to him — from sultry, urban-edged R&B songstresses (Aaliyah gave way to Ciara) to the art of incorporating avant-garde sounds into No. 1 hits (think the icy techno stabs of Usher’s ”Yeah!”). Indeed, it’s not overstating the case to say that Timbaland, who has owned the pop charts over the past decade, has redefined the possibilities of what pop music sounds like. Says Duran Duran’s John Taylor, ”I came to appreciate his place in the industry. He’s like Buddha: From the highest corporate A&R to the street kid, everybody wants what he’s got.”

All of which helps explain why one of the most notorious rappers on earth is forced to wait. And wait. So 50 Cent bides his time with his manager, Chris Lighty, and G-Unit rapper Tony Yayo, listening over and over to a new track Tim created with Timberlake for 50’s upcoming Before I Self-Destruct. Unimpressed, his 10-year-old son, Marquise, is busy playing with Tim’s PlayStation 3.

Back in the arena’s mess hall, Tim and Timberlake scrape their plates clean. Then Tim retires to his dressing room to prepare for his performance, which consists of cameos during Timberlake’s show plus a DJ set of his own during intermission. His mind still on last night’s recording session, Tim raps a 50 verse from the track they’ve been working on. The next moment, he’s shrieking Jennifer Hudson’s showstopper from Dreamgirls: ”AND I AM TELLING YOU! I’m not going!” That’s when the door swings open. Enter Timberlake. ”See ya out there, big boy!” says the superstar.

”Shake and bake!” comes Tim’s reply. (The best friends often refer to each other, interchangeably, as Talladega Nights‘ Ricky Bobby and Cal Naughton Jr.) When Tim takes the stage for his solo gig, he begins with a triumphant shout-out: ”Miami, I’m home!” (Born and raised in Norfolk, Va., he maintains a home in Miami.) Though Tim’s rave-like set has received brutal reviews — the next day the Miami Herald will dismiss it as ”pointless” — it strikes this reporter as the perfect summation of his decade-long career. Tim and studio engineer Demacio ”Demo” Castellon crank out a techno-styled mix, from Missy Elliott’s ”Work It” to ”Give It to Me,” the first single (featuring Nelly Furtado and Timberlake) from Tim’s upcoming solo album. After the 20-minute rave closes with a tribute to his late friend Aaliyah, choreographed to Coldplay’s ”Clocks,” Tim hustles back to his dressing room. Then and only then does 50 Cent get his time with the man of the moment.

For many artists, Tim has been worth the wait. This particular week, five Tim tracks chart on Billboard‘s Hot 100, including Furtado’s eerie ”Say It Right,” Timberlake’s smash ”What Goes Around Comes Around,” and Omarion’s dark, chilly ”Ice Box.” FutureSex/LoveSounds — a Tim and Timberlake co-production that yielded the Grammy-winning singles ”SexyBack” and ”My Love” — is near triple-platinum status, a rare achievement in the file-sharing-battered music business where artists struggle just to sell one million. But as music critic Simon Reynolds wryly noted on his blog: ”It gets boring, doesn’t it, acclaiming Timbaland’s genius for the 10th year in a row?” Which may explain why Tim has decided that now is the time to headline his own act, with a first-ever solo release.

Tim — nicknamed Timbaland in the early ’90s by Jodeci’s Devante Swing after the Timberland boot — was born on March 10, 1972, to Garland Mosley (an Amtrak employee) and Latrice Mosley (who ran a homeless shelter). Before entering his teens, he’d mastered turntables and drum machines. ”A couple of summers, he never came out of his room,” remembers his younger brother, Sebastian, now a rapper signed to Tim’s Interscope-distributed label, Mosley Music. ”If anyone outside our family would have seen him, they woulda thought he was cuckoo.” Yet it was Tim’s gospel-loving Baptist mother who encouraged his love for music-making, even purchasing a 13-year-old Tim his very own drum machine, a primitive model by Casio. The gift encouraged Tim, a Salem High freshman in 1986, to approach local aspiring musician and producer Pharrell Williams of nearby Princess Anne Middle School. The two formed a group, the short-lived and unremarkable Surrounded by Idiots (SBI), now merely a footnote in the biographies of the two superproducers.

At 17, DJ ”Timmy Tim” was enjoying modest success on the Virginia Beach club scene, and as the producer of a never-released CD with Portsmouth, Va., resident Missy Elliott and her group Fayze. He made ends meet with a series of menial jobs, including washing dishes at a Red Lobster, until late one night he wound up on the wrong end of a gun. The bullet passed through Tim’s neck and lodged in his right shoulder (fragments remain to this day). For nine months, Tim was paralyzed on his right side, forcing him to learn to DJ with his left hand.

Tim rarely talks about the shooting, and is, in fact, quite critical of gangsta rappers who boast of their war wounds. ”I’m not a rapper,” he says dismissively. ”I’m not talking about my scars or my battles.” Still, the shooting did help him form a bond with 50 Cent. ”I’ll tell you this,” Tim says. ”If you get shot and you survive, you feel like you’re an Incredible Hulk. Them bullets don’t hurt when they go in. But then they got that burnin’, that acid burn. Goddamn! It feels like a stove burning your blood. You feel like any minute you gonna be dyin’.”

”I been through some junk,” he sighs. ”It ain’t all been peaches and cream.” Two years after the shooting, in 1991, Timbaland lost control of his Mazda RX-7 and crashed — the vehicle ”wrapped around a tree like a candy cane,” he winces — killing his passenger, a female friend.

His luck changed in the spring of 1995, when Atlantic Records chairman-CEO Craig Kallman, then a senior VP at the label, took a gamble by hiring him to work with teenage R&B singer Aaliyah on her second album. ”He came in and played me instrumental beats,” recalls Kallman of the then-little-known producer. ”From the moment I met him, I knew that he was the next-level genius.” Tim had instant chemistry with the singer. Although she’d already had a hit album (1994’s Age Ain’t Nothing but a Number, produced entirely by rumored boyfriend R. Kelly), Tim and Aaliyah, together with Elliott, managed to remap R&B’s sonic landscape with 1996’s One in a Million. On the title track, Tim set fluttering high hats moving in sensuous slow motion against the sound of chirping birds, part of the adventurousness that yielded four hits and sales of 2 million. The disc also defined Tim’s sound. ”I’ve always tried different stuff in the studio,” he says. ”I use rakes, spoons, cans…I’m a surround-sound type of guy.”

Tim refined his wide-screen sonics further when he reunited with Elliott for her 1997 solo debut, Supa Dupa Fly. On the first single, ”The Rain,” Tim magnified a sample from soul singer Ann Peebles’ 1973 hit ”I Can’t Stand the Rain” into an echoing raindrop sound that reverberated with an indescribably funky thud. Supa was just the first in a series from Tim and Missy that altered hip-hop’s rhythmic compass, thanks to the wiry sitars and tablas on ”Get Ur Freak On” (from 2001’s Miss E…So Addictive) and the weird, sung-in-reverse refrain of ”Work It” (from 2002’s Under Construction). Along the way, the hits with other singers just kept coming, including Timberlake’s massive hit on his 2002 solo debut, Justified — the Britney-inspired ”Cry Me a River.”

Though Tim’s career has never suffered a serious dry spell, he’s still haunted by his few failures. In 2002, his album with longtime partner Magoo, Indecent Proposal, sold only 403,000 copies. Tim’s Interscope-distributed imprint, Beat Club, also failed to score; white Southern rapper Bubba Sparxxx’s 2003 album Deliverance underwhelmed, although it featured some of Tim’s most radical productions — such as a sample by the Colorado-based bluegrass group Yonder String Mountain Band. (Tim guesses the album was ”ahead of its time.” Indeed, critics now embrace it as one of the most daring, genre-busting albums of the past decade.)

Tim, who has the stocky build of an NFL linebacker, was also deeply dissatisfied with his appearance: A physical exam revealed that his body fat was an astonishing 44 percent. So he hit the gym and backed away from the music business, even putting his partnership with Missy on hold; for her 2005 album The Cookbook, she turned to other producers for all but two tracks. Eventually, he slimmed down to 10 percent body fat.

Two projects lured Tim back into beatmaking: Nelly Furtado’s comeback album Loose and Timberlake’s FutureSex/LoveSounds. The international success of both put Tim back on top of the music business — but it also brought nonstop demands for his work. ”This is one of the faster paces I ever had in my whole life,” he says. ”I gotta slow down.”

Not just yet. A few hours after a Timberlake gig in Fort Lauderdale, Tim and engineer Demo are back at Miami’s Hit Factory, mastering tracks for Shock Value. It’s 1 a.m., and the first song they work is a collaboration between Tim, Elliott, Timberlake, and Dr. Dre (one of the few production giants whose profile and body of work make him a ”get,” even for Tim). It features a lewd, strip-club-ready chorus sung by J.T., who commands over a grinding bass line: ”BOUNCE! LIKE YOUR ASS GOT THE HICCUPS!” Classic Tim, it samples giggling girls’ voices that have been transformed into an eerie, bubbling beat. Not to be outdone, Elliott adds laugh-out-loud lines, like ”Hold up! Oh, naw!/Like Britney Spears, I ain’t got no drawers!”

Around 3 a.m., a crisis arises. Tim receives news from New York that Jay-Z and his engineer Gimel ”Young Guru” Keaton are nowhere near finished with their parts of Shock Value‘s ”Ain’t I.” Jay specifically canceled plans to escort Beyoncé to the Oscars just to polish it off. As 5 a.m. becomes 6, Tim and Demo grow increasingly nervous — the deadline to deliver the finished CD to Interscope is just hours away. ”It’s crunch time,” Tim says, wiping sweat from his forehead. But as the sun comes up, and Tim’s publicist and other engineers lie passed out in sleeping bags on the floor, ”Ain’t I” remains incomplete. Despite its catchy hook — ”I’m a hustler’s hustler/A gangster’s gangster/Ain’t I?” — Tim has no choice but to eliminate it from his record. ”Jay-Z, that’s my brother. He disappointed,” he says. (Through his publicist at Def Jam, Jay-Z had no comment.)

After yet another Timberlake show and another all-nighter — this time in an Atlanta studio with rapper T.I. — Tim wearily climbs aboard the so-called ”Ritz-Carlton”; his private quarters, this bus boasts a king-size bed and his personal chef, Ralphie. It’s before 7 a.m. on March 1, but as we begin the nearly 500-mile trip to New Orleans, Tim broaches a sensitive subject: his feud with producer Scott Storch (50’s ”Candy Shop,” Fat Joe’s ”Lean Back”). In 2002, Storch was a keyboard player for Tim, even playing piano on ”Cry Me a River” — a song Storch claims to have co-produced, despite the fact that he was only credited as one of the writers. Counters Timbaland, the song’s producer: ”I beatboxed the whole thing…ask Justin, he’ll tell you.” On Shock Value’s first single, ”Give It to Me,” Tim disses Storch directly: ”I’m a real producer and you just a piano man.” Storch shot back with ”Built Like That,” a single on which he declares that he and Tim’s engineers, such as Nate ”Danja” Hills, are the true authors of Tim’s hits.

”I know he got a little record out,” Tim says, careful not to mention Storch’s name. ”I just want him to destroy his career. Because that’s what he’s doing. But I gotta be real smart. The more I talk about him, the more I big him up…. I gotta pray on it.” (Storch denied repeated interview requests for this article.)

Here’s what this reporter witnessed during a week with Tim: Like most hip-hop producers, he works with a team of engineers and beatsmiths. He treats them with the ruthlessness of James Brown; Tim is the conductor, directing them to a sound that’s in his head alone. (It’s definitely not something Tim puts down on paper — the producer cannot read music.) He describes his craft as ”the ability to hear placements where you don’t hear a beat.” He recognizes this gift in few others; his old Virginia Beach pal Williams is one. ”I kept hearing this screaming when Pharrell was working next door with Kelis. I was working with Missy. Missy was like, ‘Damn, they fightin’ over there?’ And I was like, ‘Whatever that screaming is, that’s dope.’ That’s how I [first] heard ‘I hate you so much right now”’ (the chorus of R&B singer Kelis’ 1999 smash ”Caught Out There”).

In that kind of creative environment, it’s hardly surprising that egos get bruised and feuds arise. Timbaland says it’s a good thing he and Williams (whose artists include Gwen Stefani and Britney Spears) have separate careers: ”I couldn’t have him under my wings. We would have clashed. We’d be beefing. He’s a king too.