Shirley Manson left behind her home, her country, her family and her husband in pursuit of rock'n'roll stardom. She found it in a band called Garbage. Jim Shelley met her on the road in Las Vegas.

We are in a white limousine cruising round Las Vegas.
Garbage - whose name has turned out to be a typically ironic misnomer - are in town to play the Hard Rock Hotel's venue, The Joint. Their eponymous debut album, featuring worldwide hits such as Stupid Girl, Queer and Only Happy When It Rains, may have been nominated for five Grammies, and their current album Version 2.0, boosted overall sales towards the eight million mark, but Garbage have never played Las Vegas. Only Drummer Butch Vig has been here before. A long way from Wisconsin, where the band is based, they look suitably apprehensive.

Sitting in the limo, Garbage are - with the exception of their super-exurbant, flame-haired Scottish singer, Shirley Manson - clad in black, their faces hidden pretty much permanently behind enormous sunglasses like visors, confirming the feeling that their role is, for the most part, to act as placid, semi-silent observers of her fireworks.

An incorrigible whirlwind of noise, colour and contradiction, she had arrived, as is her wont, with an orange eruption of energy, a mad laugh, and the exhortation, 'Did you MISS me?!'

She continued this way throughout the day, only occasionally dipping into despondency and the conviction that the show was going to be a disaster.

Garbage's itinerary for the day is taken up with radio promotion, some recreation on the roulette tables, and for the next two hours, a tour of Las Vegas in the company of Zander, the teenage winner of a local radio competition.

Zander is looking understandably uncertain where to put himself ever since Shirley greeted him outside the hotel by yelling, 'Unnnn-lll-ucky Zander!', giving a dirty, raucous cackly, and virtually leaping into his arms. You look like the rock star Zander,' she teases him, peering behind his black wraparound shades, as the limo snakes its way downtown. 'Lets do some drugs!' she giggles, planting a kiss on his cheek while posing for a photo.

All the signature trappings of the rock'n'roll lifestyle are certainly there in the limo for all to see: a Man Who Fell to Earth-style TV in one corner; bottles of Jack Daniels and Stolichnaya; the protection and isolation of the dark-tinted windows.

Shirley's tipple, she says, is tequila, which she announces makes her go 'completely crazy, all tingly', though she is not drinking at the moment because she has been on antibiotics. 'It's better if you combine them!' announces Zander, with rather too much enthusiasm. 'That was a joke by the way - about the drugs,' Shirley points out, filling the slightly nervous silence that results. 'Yeah,' drawls Garage guitarist, Duke Erikson. 'We never share our drugs.'

Riding down the Strip, the full insanity and demented genius of Vegas is there in all its inglorious, cardboard Technicolor. A huge black plastic pyramid (the Luxor casino) housing a replica of King Tut's tomb ('as it was found in 1922') sits next to a pink cartoon castle (The Excalibur) where the restaurant has live jousting, and most disconcerting of all, a replica of the entire New York skyline (New York, New York). 'Was that France?' someone asks, as we swing by a half-completed Eiffel Tower. Venice is also coming along nicely. Real life has been suspended. Due to lack of interest. We find ourselves in the ridiculous position of being outraged by how tacky and degrading Vegas is.

Zander the prize-winner is, of course, unfazed. Hearing that he grew up here, tourists have been known to ask him if he lives in a hotel or whether the school he went to taught blackjack. He gives Garbage some lingo to shout ('Come to Daddy! Papa needs a new pair of shoes!') once they get on to the roulette tables, the craps tables and even the 'crapless craps' tables.

The limousine tour takes in the Liberace museum, Siegfried & Roy's Secret Garden and Dolphin Environment, and an hour playing roulette at the Mirage, during which Duke wins $78 ('Come to Daddy!').

Butch Vig already has a Vegas hardluck tale to tell, softly outraged by the injustice of betting 70 times on lucky 32 losing every time.

Sadly, there is no time to see the neon, the visual feast of electric sleaze and sensation, at the other end of the Strip, the dazzling flamingos, horseshoes and dice that used to be a quintessential part of Vegas street life but has now been converted into a covered pedestrian area for tourists, marketed by the city as the Fremont Street Experience. 'Is it any good any more?' I ask Zander, who has, rightly, been deploring its demise. 'It is if you're on mushrooms!' he enthuses.

A long way from home, wary of the Vegas madness, and perhaps above all not wanting to be upstaged by a teenage prize-winner, Garbage decide that enough is enough. They have a show to play. And besides, the fact is Garbage are just not that kind of band.

Garbage are a long way from home and none more so than Shirley Manson. Manson's alliance with Steve Marker, Duke Erikson and Butch Vig (the man who produced Nirvana's Nevermind and the Smashing Pumpkins' Siamese Dream) is an unlikely story, even in the often improbably fables of pop.

From the total obscurity of an unknown indie band, in only three years, Manson has carved out a place for herself in the lineage of tough, (mad) individual icons, following on from many of her own female idols - the likes of Siouxie, Chrissie Hynde, Courtney Love and Patti Smith.

Back in 1994, the three Milwaukee musicians (aged 47, 41 and 39 respectively) were despairing of ever finding a vocalist for their new project when Marker chanced upon Manson (a mere 32) on MTV singing with obscure Scottish indie band, Angelfish - the only time the video ever aired. 'It's spooky,' she admits.

Manson's world since she joined Garbage has turned upside down, several times and in several different ways. Starting as a total stranger, she has spent virtually every day of the past four years with the three men, who have been close friends for years working in little-known bands such as Spooner and Firetown. Now Vig considers they 'are as close to Shirley as her friends from the past or even her family'.

Shortly after Marker saw the MTV video, the four of them met in a posh London hotel for tea ('I think she thought we were staying there,' mutters Butch) after which Manson packed up her things and ,without knowing a soul, left Edinburgh for Wisconsin almost immediately. 'It sounds mad now,' she has said. 'But I was desperate.'

She has lived in Wisconsin ('like Fargo without the funny bits'), existing on a semi-temporary, transitory basis ever since, living mostly in a hotel. Insecurity and a tendency to fear the worst though are part of her make-up. Even after eight million record sales, part of her still doesn't really believe things are going to work out. 'Oh, I'm in total denial. It's my way of coping with how crazy it's become.'

Manson seems to have taken this kind of Everest the Hard Way approach to its limits. Though she never stops glowing over him, her husband Eddie, a sculptor whom she met 'in a really corny way' (when he did an effigy of her for the artwork of one of her previous bands), has remained in Edinburgh. 'I don't want my partner's individuality to be overwhelmed by mine. I couldn't stand having my identity interwoven with somebody else's. It would freak me out.'

The fact that she has gone quite so far out on a limb for Garbage - for the chance to write her own lyrics and , unlike the other bands she was in, have her own say, is a sign of how determined, 'or desperate', she really was. When the tour uses were stopped at the Canadian border recently, even she was struck by the realisation that, including the crew, the Garbage tour consisted of 20 men, and her.

Her image as the hard-nosed, over-opinionated super-vixen is, inevitably, a screen. The daughter of a geneticist and a housewife, she grew up in Edinburgh as a dark, disaffected teenager with zero self-esteem and a complex about her odd and all-too-obvious appearance. She left school at 15 to play in bands, convinced that everyone hated her because she was so ugly - a notion that she was more or less in agreement with. Even now having her photograph taken driver her to distraction.

Her sister used to sit outside Manson's bedroom door listening to her playing Drop Dead Celebration, one of Siouxie and the Banshees' more miserable B-sides, over and over, convinced her sister was having a nervous breakdown. 'Siouxie saved my life,' Manson says now. 'That song was so contemptuous and horrible and that was absolutely how I felt about everybody and everything. I was so angry - for no reason at all.

Butch Vig suggests the way Manson has organised her life is possibly her way of seeking to 'legitimise her talent' - the talent se was never allowed to express in other bands. When I mention this, she fixes me with her hard, bewitching green stare, and explains, 'Well, I was in a band for a long time [playing keyboards in Goodbye Mr MacKenzie for 10 years] with a man who I was in love with, who didn't love me and who f***** women on a nightly basis, often in eye-sight. I had to learn how to compartmentalise my emotional life from my musical life and my work life.'

Vig, for one, is amazed at her transformation into an international icon. 'We took her on as a singer because we liked her and we liked her voice,' he smiles. 'Then she became the front-person for the band and then the mouthpiece for the whole band, plus we got this sex goddess into the bargain.'

Ironically, she says that fame and her high profile as the face of Garbage, has made her less self-conscious. 'It's weird but I feel less conspicuous now than I did before. I had a real problem with confidence. I couldn't go into a shop. My girlfriend used to buy my lunch at school. Nowadays, I don't notice people noticing me.'

Lyrics such as When I grow up/I'll be stable or I think I'm paranoid - and complicated make it tempting to think her crazy life is making her crazy. But she laughs, 'I've always been mad. A moody, paranoid maniac. I go from being really sweet and nice and easy to deal with to being a very difficult woman to be around. I suppose it's exacerbated by the situation but I was always a little off-kilter from my peer group.'

The boys confirm that she may have flourished but she has not changed. 'When we first met?' Erikson considers calmly. 'We knew were in for somebody who was very testy and extremely emotional and vulnerable and opinionated. Someone who can change her mind every 30 seconds. She's a lot more confident now. She's totally blossomed as a person.'

Among the artists with whom she says she feels an affinity, Manson includes Tory Amos, PJ Harvey and Courtney Love - emotionally fraught, fiery women, all pretty much seemingly on the brink of collapsing under the strain of the place they've made for themselves. In the case of Love, besides her fearsome independence, you can't help wondering if Manson identifies with her chaos.

Chaos, of course, suits some people. It is the only place they can function. Butch Vig for one seems to agree that the singer should be slightly crazy. 'Look at Michael Stipe,' he says, 'or Liberace.' Which might be taking it a bit far given the hideous, hallucinogenic nature of the contents of the museum. 'I thrive on it all,' Shirley agrees immediately. 'It's ideal for a personality like me. I am super-organised. I compartmentalise. I'm peculiarly well-suited for this. It's really alarming,' she laughs.

Her energy levels are such that, besides all her other duties, she tries to have an hour's workout before the gig, mostly, it seems, running her tiny frame to the bone a on a treadmill.

She compares the effect of performing every night as 'like letting a dog off its leash so it runs around and gets tired. It tempers my excess energies, which is good. Mostly I'm too tired to lose my temper!' Perhaps disappointingly, the Manson tantrums in Vegas are confined to a brief outburst of impatience and frustration inside the band's overcrowded people carrier. 'I'm sorry, stop the bus, I've just got to get out of here' - a problem caused by her missing her five o'clock fix of coffee (preferably from Starbucks).

The rest of the band - candidates for the Nicest Men in Music - seem placid and genial enough to absorb it all, allowing her the space to dazzle and explode. As Vig says, 'Shirley is emotionally a lot more volatile than we are. If we were all like Shirley, we would've killed each other by now.'

Today's pop stars,' Manson declares, 'are no longer just required to make music. They're required to be supermodels, actresses, diplomats and businessmen.' On the day she plays Las Vegas for the first time, instead of rehearsing and preparing, there is a hectic stream of press and promotion. She is grilled by The Telegraph Magazine, fills in a questionnaire for Top of the Pops (Favourite black eyeliner? Aveda.) She has to give away her boots - a required donation to the Hard Rock Hotel. 'They made me look like a whore [hoo-er] anyway.'

Garbage spend the afternoon before the show in a cramped red people carrier, being ferried around anonymous, airless local radio studios, recording trailers wishing listeners 'a happy holiday season'. The DJs are, for the most part, what they call the Time'n'Temp variety ('six twenny-seven in the big city, twenny-nine degrees outside') - American versions of Smashey and Nicey whose most penetrating questions to the band range from 'How do you get around from place to place?' to 'Is it hard to recreate al those sonic little sounds you do on the record?'

One DJ asks Shirley if she is still in Angelfish, as if she has kept it going - just in case. Garbage take it all their stride, with the kind of wry patience they seem to have perfected. 'How was the Liberace museum?' one Vegas DJ asks. 'Depends how you feel about Liberace,' Duke observes.

Earlier, at the museum, having declared it to be yet another reason to be depressed, Shirley's eyes shine as wide as headlights. She remains amazed by one costume made, according to the tour-guide, by six seamstresses wearing dark glasses to protect their eyes from the glare of rhinestones. The band head for the venue, happy in the knowledge that the two things Milwaukee has given the world are Garbage and Liberace, who grew up an hour from where they now live.

Duke is hatching a plan to cancel the Vegas show altogether - using the justification of being able to say to ticket-holders, 'Hey, you took a gamble, you lost!' Vegas, of course, is the only town on the tour where bands are competing against the allure of the blackjack, the roulette and the Megabucks slot machines (a pot of $23 million and rising), not to mention acts such as Tom Jones and David Copperfield. 'Copperfield's in town?!' drawls Duke. 'Ah man, if I'd known Copperfield was in town…'

As we arrive for the sound-check, outside in the car-park a Japanese girl sees us and, talking on her mobile phone, excitedly starts walking towards us. She clutches Manson's arm, and hands her the phone to talk to her friend, while she stands there sighing. 'Oh Shirley, Shirley, Shirley', sobbing with excitement.

Being on the road is always pretty bizarre,' Steve Marker utters with typical laconic understatement. In Fresno, the atmosphere was 'psychotic, really strange. A lot of people with painted faces and sprayed hair', ponders Steve. 'One woman who had taken her top off and sprayed a Garbage logo on her tits with a smiley face and a cigar.' Apparently, someone says, she had won a competition to get in. 'Best sprayed tits,' deadpans Duke. In LA, the glamour gig, they had been hanging out with famous fans Courtney Love, Michael Stipe and Bob Saget, host of America's Funniest Home Videos, which at least impressed Duke's mum. 'I said, "You're…" and he said, Yes, I am",' remembers Duke, impressed.

The band had driven overnight on the tour bus (Manson says she has never flown first class) watching episodes of Twin Peaks on video, listening to PJ Harvey, Hole, and on tape, The Terror Inside, sent in by a fan. 'He had a horror movie in his head nad this was the soundtrack,' mutters Vig. Shirley raves about All the Pretty Horses, and her current favourite, writer Rick Moody - reading and sleeping being her main way of staying sane.

The superficial glamour of Vegas is pretty much all anathema to Garbage. Having done it all before in other bands, they've put their wild times behind them. On the Jo Whiley show, for instance, Manson took issue with Goldie about bands smashing up their hotel rooms, making a stand for 'the poor cleaning ladies who have to clean up after them'. In three days on tour with them, I can report not one sighting of a single joint, line or pill of any description, confirming Garbage's position as an example of post-modern rock'n'roll.

In their artwork, their videos and the sound of their albums, Garbage are modern and iconic, clever and above all cool - New Order meets Nirvana: a perfect marriage between arch, shiny, Scottish pop (Altered Images, Win, Paul Haig) and nihilistic American grunge, with some garage and some Roxy Music thrown in.

In the end though, it's more fitting to judge Manson in her most natural element - on stage.

'I've waited my whole life to say this,' she greets the audience in The Joint, all semblance of cool utterly abandoned. 'HELLO LAS VEGAS!' On stage, the stylised gloss of Manson's songs - about insecurity and revenge, bitter romances and her own personal failings - is blasted apart, principally by her energy and anger. Her performance is a mix of home-girl pacing, relentless shadow-boxing and virtual head-banging so that even a pop song as infectious as Special becomes an expression of aggression and anger.

The show, which started with an intro tape of Mahler, closes with the down-beat, sugar-coated put-down, You Look So Fine, ending with a brilliantly intricate, overpowering wall of sound. Over the applause, you can just about hear Shirley's words, let's pretend/ happy end echoing around the hall: a perfect post-modern finale.

The Vegas madness had started at the airport, where there are slot machines while you wait for your luggage. It ends, predictably, in the casino, where there are no clocks and you never see daylight.

After the show, we get drunk and gamble, like ever one else in the place. The girl playing blackjack next to me is so drunk she has knocker her beer bottle over three times, but, of course, they keep taking her money. I am still trying to get over the fact that the Hard Rock Hotel's motto is 'Save the planet.' Earlier a woman from Arizona had asked me if they have coins in England. Someone had bemused Shirley by trying out his Gaelic on her. His name was Clay Bender, which goes right up there with the day's best Vegas names: Vince Morocco, Art Rasco, and Larry Changes.

It has gone beyond late into early. If we are feeling fine, it is probably because, we learn later, the casinos pump the place full of oxygen. Cocktails are free but coffee costs $1.50. At the bar, an English eccentric, trying to extricate himself from the clutches of a call-girl with fingernails like talons, tells her, thanks, but he's 'looking for something more romantic'. 'Hey honey,' she says, not missing a beat. 'I can do romantic.' Duke and Butch are cleaning up, building up high piles of the Hard Rock Hotel's $25 Jimi Hendrix chips. 'Colour me out baby,' Vig tells the croupier, when he cashes his chips, using Zander's favourite phrase. 'Ace me,' we all say when the blackjack dealer deals a 10.

Shirley is drinking tequila, pouring it into her vodka and cranberry, virtually tipping it down me, insisting 'it tastes quite nice'. (It tastes disgusting) Despite the crowd's acclaim and The Boys' view that it was a blinding show, the Queen (as she is referred to by the others) is not satisfied. 'It takes a lot to make me happy,' she smiles, slightly sorry. 'You should have seen Santa Monica.' Earlier, she admitted that the way her life is nowadays will not necessarily make her happy, or more positive. Since she was 15, it is just what she has been doing all along.

She is still on a winning streak, having built up her winnings to a mighty $4.50 - which she is determined to lose so they can get away, declaring Vegas to be 'appalling, tawdry'. Somehow, though, she doesn't go.

Unlike the others in the band, there is no real unwinding. Even playing the slots, she is constantly accosted by fans wanting her to pose for photographs or sign something. Still, amid all the bright lights and the relentless ringing, she looks quite at home.

The last time I see her, she is wedged between a grinning middle-aged Japanese businessman and a large woman wearing a hand-painted T-shirt with the words 'Die For You' written on it, practically squeezing her to death.

When I ask Butch Vig about my theory that someone slightly crazy needs a crazy lifestyle to make them feel remotely sane, he just says, 'That's probably true. In some ways, it's easier. Being in a band is sort of a way of escaping reality.' The way Manson has fenced herself off - inside Garbage, inside Wisconsi, away from her family, her home country and her husband - seems to me an extraordinary statement. It shows a particular kind of courage and the will of someone so driven by the determination to forge an identity, assert her independence and prove herself, she will only do it by herself. With her set of insecurities and anxieties, this is, presumably, the only way she could feel she has done it at all.

The scene around her seems just like Vegas madness, but it is her environment, her desired lifestyle. It is her chaos.

Garbage's single 'When I Grow Up' (Mushroom records) is released on Jan 4 to coincide with their British tour.

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