1. GUESS WHO'S BACK

For a man whose last public act was to splash his wedding across the pages of Hello! magazine in 2006, where he proudly showed off his new wife Kim, daughter Hailie and an endearingly ill-fitting lounge suit, Marshall Bruce Mathers III was in a strangely reclusive mood when he began his long-awaited return to the public eye three months ago.

The 36-year-old white rapper, better known as Eminem but occasionally styling himself Slim Shady, turned up at the launch of his autobiography, The Way I Am, at a sports shop in Manhattan wearing the uncomfortable look of a man to whom fame and fortune have brought little in the way of happiness – and a healthy dose of insecurity.

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Fellow guests, most of whom he'd personally invited, as it was, after all, his party, were ordered not to speak unless spoken to. Book-signing was out of the question, since Eminem doesn't "do" autographs. He posed briefly for photos, frowning behind a pair of spectacles, before disappearing downstairs with fellow musicians 50 Cent and LL Cool J.

"Em was pretty much a rabbit in headlights," recalls Hattie Collins, founder of the urban lifestyle magazine RWD, who was present. "We were told not to talk to him. People like 50 Cent were walking around, shaking hands and being generally sociable, so it was a friendly event. But I guess he just didn't feel ready to be back in the public eye."

Twenty minutes later, Eminem re-emerged. He breezed through the room, pausing only to answer a few questions for a local hip-hop station (earlier that day, he'd given a sometimes monosyllabic but occasionally intriguing half-hour interview to Radio 1's Zane Lowe). Then he was ushered into a black SUV and driven away.

So began Eminem's great comeback. As the opening salvo in a musical renaissance that has been four years in the making, and will culminate very shortly in the release of an album that (if you believe the hype) could end up being one of the greatest records of recent times, it left a certain something to be desired.

2. MY NAME IS...

Things weren't always like this. A decade ago, Mathers – an angry young man from the wrong side of Detroit – decided to bleach his hair, adopt the alter ego Slim Shady, and transform the landscape of popular music.

In six years, from 1999 to 2005, he recorded five extraordinary albums which sold nearly 50 million copies, and gave the city of Motown a new chapter in its musical history.

Today, Detroit is ground zero of America's economic meltdown, its motor industries bankrupt and its housing market worthless. Entire streets in Warren, the bleak suburb where Eminem grew up, can be brought and sold for less than a family car. Hotels, shops and even bars on 8 Mile, the road that gave its name to the semi-autobiographical film Eminem made, have bars protecting their workforce from feral locals. Across great swathes of the city, the only surviving industries involve prostitution and drugs.

Visitors are warned not to venture out of doors after dark – though the bitterly cold Michigan winter hardly encourages such adventure, particularly now that the state has run out of money to grit or snowplough its roads. Last week, the corpse of a homeless man was discovered encased entirely in a block of ice in the basement of a city-centre skyscraper. No one knew how long he'd been there.

Eminem grew up at the tail end of his town's decline from prosperity to despair. And he chronicled it all with outrageous energy, and a wicked sense of humor. His best music overflowed with with linguistic vitality and literary energy.

Eminem proved that a white man could master hip-hop, and inspired an extraordinary devotion from often-disaffected fans. Eventually, he was hailed as the greatest rapper alive, filling stadiums and front pages with consummate ease.

At first, Eminem rapped about his soap-opera life – complete with dysfunctional relationships, a trailer-park mother and his impoverished childhood. When he achieved tabloid notoriety, he rapped about that. Either way, he turned his life into public property.

Eminem's was the "other" America, a gritty world of industrial decline and social decay rooted in his home town. His music was often angry or pugnacious, but could also be lifted by his sense of humour and by the anthemic intensity of hits such as "Lose Yourself", which won an Oscar, and "Stan", one of the greatest hip-hop tracks of all time.

"He came from us. He was one of us. We saw him go from being a person we'd see every Saturday at the hip-hop shop to the biggest star in the world," recalls Marv One, a Detroit rap artist who had a cameo role in Eminem's film 8 Mile. "What happened with that guy was awesome."

As his fame grew, Eminem became a magnet for controversy. He was accused of glorifying misogyny, homophobia, bad language and violence. He was arrested on gun charges. On one occasion, George Bush, upset by his lack of respect for the forces of conservatism, labelled him: "The greatest threat to America's children since polio."

Yet, with time, he secured a following that stretched across every demographic of the record-buying public, inspiring fans as incongruously middle-of-the-road as Alan Yentob and Jenny Agutter.

In one headline-grabbing endorsement, confirming him as the favourite cultural influence of the chattering classes, a white-haired Seamus Heaney declared him, in all seriousness, the saviour of modern poetry. "There is this guy Eminem," said the Nobel laureate. "He has created a sense of what is possible. He has sent a voltage around a generation. He has done this not just through his subversive attitude, but also his verbal energy."

Then, at the height of his remarkable fame, Eminem disappeared.

3. ALL FALL DOWN

The CCC club, or at least its former premises, sits between a barber's shop and a pawnbroker on a desolate stretch of 8 Mile, the road that runs east to west across Detroit, separating the traditionally black inner city from its chiefly white suburbs. Today, like many businesses in a city ravaged by the decline of the car industry, where family homes change hands for as little as $2,000, it has ceased trading. But on 11 April 2006, the venue bore witness to an event that has assumed totemic significance in the Eminem story: the killing of 32-year-old DeShaun Dupree Holton.

Holton, better known as the rap artist Proof, was Eminem's closest friend. They had met aged 14, at Lincoln High School in Warren. Proof encouraged him to rap, nurtured his talent, and recruited him to the Detroit rap collective D12. Later, he became Eminem's "hype man" – the performer who precedes a rap superstar onstage, warms up the crowd, and provides his backing vocals.

Proof's killing (he was shot three times in the head and chest during a bar brawl that has never been properly explained) affected Eminem deeply. "I have never felt so much pain in my life," he recalled in The Way I Am. "I've had death in my family before – two of my uncles committed suicide – and it took chunks out of my life... After he passed, it was a year before I could really do anything normal again. It was tough for me to even get out of bed, let alone write a rhyme... my brain was scattered."

Eminem was already showing signs of fatigue. The previous August he'd cancelled a world tour, claiming to be exhausted after years on the road and suffering from a dependency on sleeping pills. Losing Proof was a knockout blow. It prompted him to withdraw completely from the world, retreating to his vast mansion in Clinton Township, just outside Detroit.

For more than two years Eminem barely ventured out of doors, let alone appeared in public. Not a single record was released, or interview given. Noting that his last original album

came out in 2004, the media filled the vacuum with rumour and revelation.

Grim stories began alleging that the usually muscular star, who kept fit through a mixture of workouts and energetic stage performances, was bingeing on junk food and had ballooned in weight to 240lb. Paparazzi pictures emerged of him in a wheelchair, following a bout of pneumonia. His marriage to Kim fell apart again, and his estranged mother published a muckraking memoir.

By the middle of 2008, with his career still on hold and his private life in turmoil, concerned fans feared that Eminem was going the way of Michael Jackson. Former associates in Detroit described him as "missing in action".

More worryingly, reports began suggesting that Eminem had begun to doubt his own abilities to "hear a hit". He seemed consumed by self-doubt and destined for retirement. Though only in his mid-thirties, headline writers dubbed him the Howard Hughes of hip-hop, and said he'd never rap again.

But they were wrong.

4. RELAPSE

On 15 October 2008, Eminem announced a comeback. The news was broken during a late-night interview with Shade 45, a satellite radio station he part-owns, when he announced that he was working on a new album called Relapse. The record would be produced by Dr Dre, a long-time collaborator who signed him to the record label Interscope in the late 1990s.

Within hours, news of his return had electrified the record industry and sent ripples of excitement through his still-loyal fanbase. After hearing him perform a two-minute riff titled "I'm having a relapse", Shade 45 listeners reported him to be back on top of his game.

Days later, a second track called "Crack a Bottle", featuring 50 Cent and Dr Dre, was leaked on the internet. It garnered some solid reviews, in spite of being by no means a finished version. (Eminem claimed to be "really heated" about the leak in an email interview with Billboard, saying: "It's like someone catches you peeping in your window before you got the Spider-Man costume all zipped up!")

Today, the album is still being completed, in conditions of near-total secrecy. The release date was originally slated to be 23 December 2008. Then it was put back to 2 March 2009. At present, it looks like hitting the shelves in the middle of next month.

"We've been told nothing about this record, and I mean nothing," says a source at Polydor, the multinational owner of Interscope. "It's top secret. In terms of timing, the plan is to release it between new records from 50 Cent and Dre, who are both also signed to Interscope. Whenever it comes out, it will be huge."

The hype machine would hardly suggest otherwise. But there are intriguing signs that a blockbuster record could be in the making. In October, Elton John was spotted breezing into the Ferndale recording studio where Relapse is being recorded.

"He stayed half a week," says a witness to the visit. "No one realised the significance, though the Detroit Free Press did mention that Elton had been in town. He and Em worked together before, when they did that duet at the Grammys, and had always said that they'd record something original together. Em has huge respect for Elton, and the feeling is mutual. Elton really gets his music. Anything they produce will be total dope: some of Em's biggest records have been collaborations with mainstream pop stars – Dido on Stan, for example – and they really don't come much bigger, or more mainstream, than the man with the red piano."

The death of Proof has also given Eminem fresh material to mine (essential for an artist who writes mostly about himself). Although he could be forgiven for rustiness, he is reported to have been "hitting a roll" in the studio.

"In the later albums, he'd started to throw some quite political stuff in about Bush, and also talk about his family life, and risk soppiness with the lullaby track 'Mockingbird', about Hailie," says Eminem's biographer, Nick Hasted. "This time, I would think there will be some anger on the record, as there always is, but its overall theme will almost certainly be Proof; I would expect a fairly powerful tribute."

Any fears about Eminem's physical condition can also be laid to rest: at his book launch in October, he bore no trace of excess weight. There's a reason for that: he's been undergoing gym sessions with the famous boxing trainer, Emanuel Steward. "The guy is in excellent shape now, excellent," says a source close to Steward. "He's a workout maven, and one of those healthy body, healthy mind people, and right now, he's in the right place to just blow the world away."

5. THE REAL SLIM SHADY

It is a little-known fact that the only book Eminem read as a child was the dictionary. He pored over it, searching for words that rhymed with each other that could later be pulled out of the bag during the freestyle rap "battles" that provided his education in hip-hop.

The years spent studying the English language lie at the core of his technical brilliance. They turned him into the greatest rapper of his time. But they did so at a personal cost: for Eminem could be uncharitably described as an anorak. His life starts and ends with music. He writes constantly, scrawling lines on sheets of notepaper in a crabby handwriting. When he's not composing new verse, or messing around in a studio, he'll be listening to hip-hop. "The guy's a studio rat," says producer Terry Simaan, the owner of Oh Trey 9, one of the Detroit's most influential hip-hop labels. "If he feels like it, he'll spend 12, 15 hours a day in a studio."

As a result – and this is critical when considering the potential impact of Relapse – Eminem's so-called "missing years" have actually been surprisingly productive. "He's never stopped recording. Ever," adds Simaan. "I hear they've got over 300 songs in the can from what he's produced in the last three years. I've seen him write. He's a fast worker. He'll write one line, then three lines, then four lines, in all separate parts of the page. Then he'll come back to it, and say this is a sweet line, or that's working for him, and just pull everything together almost instantly. The guy's a total genius."

In other words, Eminem now has a vast catalogue of material from which to cherry-pick the dozen-odd tracks that will make up Relapse. Like a mad genius, inside his Detroit mansion, he has been stockpiling an extraordinary collection of unreleased music. It is now being polished by Dr Dre, a notorious perfectionist.

"Eminem had a career break. But I wouldn't say it was a rest," says Mark Hicks, the former manager of D-12, and an occasional acquaintance. "He's a lover of music and making music, so despite what everyone said, he never stopped working, or quit rap. He was in the studio every day. He just didn't want to go on tour, or have to do everything that comes with selling an album."

Hicks says that Relapse will see Eminem back to the peak of his talents, re-adopting his old, aggressive, alter ego Slim Shady. "On his last record, I think how he put it was that he wanted to say goodbye to Hollywood, and stop being part of the entertainment world any more. But he's a special guy, he's been on a roll, and he was never going to just disappear for ever."

6. ROLE MODEL

In the summer of 2003, Eminem bought a vast, 29-room mansion in Rochester Hills, an upmarket suburb of Detroit. It was previously the property of the the K-Mart chairman Chuck Conaway, and boasted heated marble floors, mahogany panelling, a helipad, two swimming pools and several acres of landscaped grounds.

Strangely, Eminem has barely lived in the mansion, choosing instead to reside at his smaller gated property in Clinton Township. Friends say the second home is an expensive white elephant, aimed at throwing obsessive fans off his scent.

"Proof's death bothered Em a lot, and he started to get a bit paranoid and worry that he might be next," said one associate, speaking on condition of anonymity. "It also made him realise his responsibilities. He didn't need any more money, and he hated being away from his daughter, so he decided that he wouldn't leave her alone to go touring any more."

As a result, Eminem has spent recent years reinventing himself as a family man. His domestic circle includes Hailie and her adopted sibling Alaina, who is the daughter of his ex-wife Kim's sister, together with his brother Nathan who, while also pursuing a career in hip-hop (though apparently as a promoter rather than artist), completes the domestic set-up.

"A lot of my security guys also work for Marshall as bodyguards," says Mike Danner, the manager of St Andrews, the famous Detroit hip-hop venue featured in Eminem's semi-autobiographical film 8 Mile. "From what they tell me, when he's not in the studio, he's with his kids, either playing with them at home, or taking them to school."

Eminem's recent maturity is probably related to his own upbringing. He was brought up in crushing poverty by a single parent (his father Marshall walked out on his mother Deborah shortly after he was born) and has always been unreservedly anxious to give Hailie the childhood he never had.

He maintained a healthy suspicion of the hangers-on that attach themselves to a rising star, and decided to forgo the trappings of success, even flying charter (unthinkable for a rap star) until 2001. His enduring determination to make the most of what remains of fatherhood means he's unlikely now to go on tour to promote Relapse.

"I have one story that sums Em up," ventures a friend. "After his second album he was in the jewellery store. He really liked a watch, but was worried that he'd not be able to afford it, so called his manager, Paul Rosenberg, to check he had enough cash. The watch turned out to be $15,000. At the time, Em was one of the hottest artists on the planet. He was worth millions. So Paul told him not to be silly, and just buy the watch.

"But Em was like, 'I don't want to run out of money, I want my daughter to be able to go to college.' That's really tells the kind of guy he is. I think fame surprised him. I don't think he really had realised who he was what kind of money he had, and what he'd achieved, until suddenly he woke up one day as the biggest star in the world. Whoever you are, that's going to make you a bit nuts."

7. CRACK A BOTTLE

The rapper Nas recently contended that hip-hop is dead. Critics say it has run out of steam, stopped evolving, and in common with the rest of the music industry, reached a point of commercial hopelessness and artistic stagnation.

At the end of his autobiography, Eminem addresses this question head-on, casting himself not as a potential saviour of a dying genre, but as the master chronicler of his own, contradictory life story. And it is this, combined with the richness of Eminem's soaring talent, that makes the arrival Relapse feel so pregnant with possibility.

"Whether I'm someone's favourite rapper or not, whether I'm thought of as one of the best, one of the most half-assed, whatever it is, I am one of the most personal," he explains. "That's why people relate to me, because I show so much of myself. That's why random taxi drivers call me 'Marshall'. And the reason I put so much of myself out there in the first place is because I had no idea I was going to be so famous. I had no idea, no fucking clue. If I had to do it again, I don't know if I would. I'm glad, though, that my music has brought people together."