They came, they raved, they conquered.

There is no alcohol in the green room. There is Cozy Chamomile herbal tea, a fruit bowl, a plate of red velvet cupcakes and a copy of "Art & Sole," a book about sneaker design, with a note that reads "For Seb." There's a TV connected to a Sony PlayStation 3. There's a production assistant, who enters 15 minutes before Swedish House Mafia's expected arrival to turn off the harsh overhead fluorescents and light some pillar candles. But there is no posse, no hangers-on, no waiting party of industry well-wishers who would seemingly turn up for one of the arena-packing act's last performances ever. And, consequently, there is no tequila, vodka or even Red Bull.

Steve Angello, Sebastian Ingrosso and Axel Hedfors (aka Axwell), the members of Swedish House Mafia, are en route from the San Francisco Airport, where their private plane has just landed. They've opted to make the 30-minute flight back and forth to Los Angeles every night of this five-night stand at the Bill Graham Civic Center (the longest sold-out run for a single act in the venue's history), rather than stay in San Francisco, because L.A. is home, and their wives and children are there. When they finally arrive, Axwell walks in holding the hand of his 3-year-old son, a hip little boy with long hair and red, white and blue sneakers with Mercury wings on the back. "He picked those out himself," Angello says.

The men of today's Swedish House Mafia are very different from the ones who first said hello to the U.S. EDM industry six years ago, three of countless European DJ/producers looking to make something of their modest awareness stateside. Back then, they were in their 20s, and the party was the thing: the party, the after-party and the party after that. There was plenty of tequila, planes jetting from one international dance music hot spot to another, summers in Ibiza and winters in Miami. But nothing was that serious, because not much was at stake: A $7,000 nightclub gig, a track release on one of their digital-only labels, a slot at a small festival.

Now, EDM is big business, and SHM is one of its most rapid and mysterious success stories. After years of solo gigs and occasional one-offs under the SHM banner, the group released its first track, "One," in May 2010. Five more singles make up the total sum of its original output. The latest, sweeping dance ballad "Don't You Worry Child," is its biggest hit yet, peaking at No. 6 on the Billboard Hot 100 with more than 1.9 million copies sold, according to Nielsen SoundScan.

In December 2011, SHM became the first DJ act to headline New York's Madison Square Garden, selling it out in nine minutes. It has an international sponsorship deal with Absolut Vodka, including a film-quality TV spot featuring the group's members and one of its six singles, "Greyhound," made especially for the brand. It put all 52 dates of its international farewell One Last Tour on sale on the same day, and sold them out in short order. In the United States alone, there's 15 shows at seven venues, all with eye-popping pyrotechnics aimed to be, as Axwell says, "the best party of your life." On Feb. 28, SHM lit up the New York skyline in a different way: To mark Black Tie Rave, SHM's benefit for Hurricane Sandy victims, the city's Empire State Building displayed the colors of the Swedish flag. Not bad for a gang of DJs with funny names.

So when SHM announced in June 2012, six months after its original MSG triumph, that it was over--the members would continue as solo artists, but Swedish House Mafia would be no more--fans were stunned. "We came, we raved, we loved," read a statement on its website. When it closes Miami's Ultra Music Festival on March 27, its set will purportedly be its last ever as a group.

As the kiddie-proof Zen of the Graham green room shows, "the boys"--as everyone on their team refers to them--have different priorities than they did even a few years ago. (Ingrosso, 29, and Angello, 30, each have two daughters under the age of 3, while Axwell, 35, is expecting his second son.) And while that's a factor, it's not why they've decided to call it quits at the peak of their power, right when they're about to go from a cool EDM act to a major force in music. The gravity of the decision isn't lost on the trio.

"We're letting go of something huge," Axwell admits. "We got handed the key to the city and we said, 'Thank you, that's awesome. There you go.' [Mimes handing key back.] So, it's stupid in many ways. It's also a little bit refreshing."

"I think it's a lot of stupid," Ingrosso cracks.

The story of how Swedish House Mafia separated itself from the pack of DJ hopefuls to find success on its own terms is something of an epic romance, with unlikely heroes, dogged idealism, passionate breakups (and makeups) and, now, the proverbial ride into the sunset. Along the way, the act and its team pushed the boundaries of the 360 deal, dismantled the notion that big acts need big albums and introduced corporate branding to artist development. Yet it's SHM's final act--the walking away--that might resonate the loudest from its brief, brilliant career.

Also part of the story is the group's behind-the-scenes fourth member: manager Amy Thomson. "She's the driving force for any of this to ever take place," Axwell says. "She was the reason we found ourselves in the studio making 'One' together. She's definitely an equal member."

"We didn't think that she was so important until we didn't have her anymore," Ingrosso adds. "It's like any relationship: You don't know what you have until you lose it."

The band cut ties with Thomson, its first and only manager, in December 2011--just before the MSG gig--and joined Three Six Zero, home to Deadmau5 and a Roc Nation affiliate. But SHM left six months later, and Thomson reunited with the group last summer.

"We had a massive fucking argument, and then we massively fixed it," Thomson says.

Thomson has a reputation for being tough and uncompromising. But everyone who describes her in those terms uses their next breath for a compliment like "genius" or "visionary." In addition to her agency, ATM Artists, she heads up booking and marketing for the new Cirque du Soleil-themed nightclub Light at Mandalay Bay in Las Vegas and serves as a music and marketing consultant to supermarket magnate Ron Burkle's investment firm Yucaipa.

A child of the U.K. acid house revolution and its resulting nightclub subculture, Thomson worked at iconic London club Ministry of Sound before joining X Ray Touring, which at the time had clients like Coldplay and Blur. Even in the early days, her strategy for SHM--the core engine of its success--combined the ethics of live and club culture.

"The inspiration was, 100%, sitting in an office with five rock agents and loving how structured it was," she says. "Band strategy is so tied to the on-sale date; the artwork even reflects that. A lot of electronic culture is so available that it doesn't create demand in a way that makes you able to do a hard-ticket show."

She first met the boys in 2004, when she reached out to Angello to see if he'd use her music download site, Tracks to Burn, to promote releases on his label, Size Records. "She just called me out of the blue," Angello says with a grin. "Some British woman raving about some stuff."

Angello introduced her to the other two guys, and they decided to work together, casually at first. Despite being childhood friends, Angello, Ingrosso and Axwell were primarily DJ'ing separately at the time, and their careers were flourishing by the standards of the day: club gigs around the globe, dedicated fans, respect for their music. Angello's Size came first, followed by Ingrosso's Refune and Axwell's Axtone, and all the labels grew in clout along with their careers. They played one-offs as SHM, including a 2007 gig during Miami's Winter Music Conference at a tattoo-themed nightclub on grimy Washington Avenue. In May 2010, inspired by Thomson's rock agency experience, SHM attempted its first hard-ticket gig, at London's Brixton Academy.

"Looking back, I don't know what we were thinking," Thomson says. "We had a full orchestra join us for four songs. But we worked hard, moving 10 tickets a day, working the High Street stores. We sold out the day before the show, and it was like, 'Fuck, this means something.'"

Spurred by Thomson, the act recorded and released the anthemic "One" with Pharrell Williams, laying the blueprint for the epic, celebratory sound that became its signature. EMI heard the record and signed SHM to a 360 deal, rereleasing the track in June 2010. Under that agreement, the group released the documentary "Take One" just after its second single, "Miami 2 Ibiza," in November 2010.

"A traditional rock band would go on tour, and then a documentary would come after the tour to look back," says the film's director Christian Larson, who today serves as SHM's creative director. "What we did with that film was show their frustration, ambition and tremendous will to become something big.

"With DJ marketing, it was always big logos and neon colors, never a face," he continues. "We started to build connections between them and the fans by showing their different personalities." It helps that you couldn't cast a reality show better: Axwell is thoughtful and reserved, Ingrosso is boisterous and generous, Angello is brooding and direct.

In March of the following year, the group forewent a set at Ultra, instead deciding to host its own full-day event, Masquerade Motel, in a tent usually used for fashion shows in Miami's South Beach. Thomson used gradual reveals to market it: a teaser with minimal information, phased lineup announcements (other DJs, like Calvin Harris and Pete Tong, played throughout the day) and presales for the most dedicated fans. They sold 12,500 tickets in a matter of minutes.

Soon after, Thomson came to New York with an even bigger gig on her mind, and started scouting for locations. But first, she had to break some news to her partners at EMI in a conference room full of executives, with the entire L.A. office joining through video.

"I walked in and said, 'There is no album, and all of you can bite me,'" Thomson recalls. "'Frankly you should be ashamed of yourselves that you asked us to do an album. Now, let's discuss Plan B.'"

"And there we were with our plans in our hands," Glenn Mendlinger, GM and senior VP of Astralwerks, EMI, says with a laugh.

EMI ended up getting "Until Now," a collection of the band's six tracks, its one and only remix (Coldplay's "Every Teardrop Is a Waterfall") and some of the members' work as solo artists. Plus, the label got three additional songs ("Antidote" with rave act Knife Party, "Greyhound" for the Absolut campaign and the nearly double-platinum "Child"); a photo book; another documentary, scheduled for release later this year; and the promise of SHM pop-up stores filled with merchandise in Sydney, Stockholm and New York. While Thomson says the partnership is "on lock" now, she was frustrated by the label's initial focus on the traditional "three singles and an album."

"We did a 360 deal with EMI, but EMI is still a record company," she says. "You want to be a 360 company, you're telling me you know a shit-ton about merchandising, branding, all that other stuff, and yet you're thinking within the parameters of a record company?"

Mendlinger praises Thomson and Larson's "fan first" philosophy, "Part of their mission statement was to build a brand just like Disney and Coca-Cola, and they did." But, well, he'd still like some more music. "It would have potentially been a more elongated campaign if we had more original tracks to work," he says. "Perhaps we would have been working third and fourth singles as follow-ups to 'Child,' deepening the experience with fans."

That argument nearly became moot with the band's next act: another Thomson special, a fan-focused presale structure and coded scavenger hunt for information about the gig, resulting in a sellout of Madison Square Garden in minutes. The moment was pivotal, not only because of the surface achievement.

"We did MSG and everything changed," Thomson says. "Let's just say every worm in the garden came to the surface. 'The scene is so big, you are so big, look at what you did.' You start listening and you get a bit, 'Ooh, what?'"

The boys won't talk about it directly, but all the whispering must have gotten to them, because they left Thomson for Three Six Zero and its powerful L.A. connections, which prompted their moves west. Thomson wasn't there for the MSG gig on Dec. 16, which she calls "the hardest day of my life."

While it wasn't long before Thomson and SHM reunited, by the time they did, the boys were ready to walk away from the brand they'd built with Thomson's help in pursuit of solo careers. Angello joined Red Light Management, and is planning an artist album after all. Ingrosso will release his next single on EMI, and Axwell is releasing a single through Sony/Ultra Music that is linked to a global campaign for Carlsberg beer. Both Ingrosso and Axwell are staying with Thomson, as does the SHM brand and any future business.

Working with William Morris Endeavor agent Sam Kirby, the reunited team started to select venues and promoters for the One Last Tour, before going their separate ways.

The decision, Axwell says, stemmed from the need "to challenge ourselves creatively--just take away this thing and see what happens to us." Or, Angello says, "Let's put it like this: How interesting, for you as a consumer, would it be to go to Masquerade Motel on the beach for the 20th time?"

He's right: How many times can you go to the best party of your life? But if this is going to be it, the One Last Tour is the way to go. The sound system is exceptionally clear for its intense volume, making every bass boom a gut slap. The four-tiered booth structure is covered in LEDs, and high-resolution projections bring it to life, with fractals, wormholes and racing greyhounds. The boys start the show standing in front of the thing, men dwarfed by the machine of their own making.

For Thomson, the decision to end now is "what's needed. We can chase the dragon of being 21 again, or we can take this journey gracefully. We have three talented individuals with huge careers ahead of them. They need the soul food of doing it alone."