When the email arrived last May, the Kolacny brothers thought it was some kind of joke. It purported to be from Hollywood, an enquiry about their music. There was a particular song they’d done that would perfectly suit the trailer of a forthcoming movie, it said. “Yeah,” the brothers thought, “right.” It wasn’t the sort of email that two classically trained musicians from a small Belgian town were used to receiving. But the request was genuine. And the film turned out to be The Social Network. It transpired that the director, David Fincher, is a huge fan.

The song in question is a hauntingly beautiful acoustic reworking of Radiohead’s Creep – sung by a female choir accompanied by a single piano. In July 2010, two months after the brothers received the email, the Social Network trailer was released – featuring more than two minutes of Creep. The powerful music was centre stage, heightening a growing sense of unease like a chorus of fallen angels. Like the film itself, the trailer has been a huge global hit – more than 250m people have seen in the Cinema, on TV or online. Thanks in part to the subsequent buzz on social media, traffic to the brothers’ website went through the roof: their interpretation of Creep is an internet phenomenon, watched in various forms around 10m times.

A record-label bidding war erupted in America – but the brothers chose to sign with Atco, a subsidiary of Warner, with whom they had been negotiating prior to the whole Creep furore. They are releasing an eponymous album in 2011, their first in the US and UK (in Britain, the album will be released on Wall Of Sound). This year they are also embarking on their first American tour, including dates in New York, LA, Chicago and the Coachella and SXSW festivals, with a debut performance in Britain to follow.

The Social Network trailer shone a spotlight on the unique musical project that is Scala & Kolacny Brothers – they are an indie-rock choir, comprising of the two Kolacny brothers, Steven and Stijn, and Scala, their all-girl choir. Steven plays the piano, Stijn conducts the choir. The brothers usually work with 30-40 singers aged 16-26 at a time, but these days have more than 200 girls on their books, ensuring plenty of cover for their increasingly busy schedule.

Scala & Kolacny Brothers take classic rock and indie songs and reinvent them as elegiac hymns – to breathtaking effect – with the piano often the sole accompaniment to the voices. On occasion they also use drum machines, sequencers and synthesizers, and also often perform with a full rock band. The new album includes versions of Smells Like Teen Spirit (Nirvana), Champagne Supernova (Oasis), With or Without You (U2), Use Somebody (Kings of Leon), Nothing Else Matters (Metallica), Everlong (Foo Fighters) and more. Creep also features, as do three original compositions – Seashell, Masquerade and Our Last Fight.  

It is Steven who picks the songs and re-imagines them for the choir, sometimes altering the key, the tempo, doubling the choruses, but “we always keep exactly the same lyrics,” he says, “that is very important – but the mood of a song can change quite dramatically. It’s very strange, because if you hear Radiohead singing Creep and you compare it with our version, it’s exactly the same length, same words, same notes, same key. But it’s completely different”.

Rock and indie music works best because “the beating heart of the songs is often very black and very emotional, and the female voices of the choir add a certain melancholic touch”, says Stijn. “Sometimes they bring out whole new dimensions in the songs – our version of Nothing Else Matters could be classical music; its sound is nothing to do with Metallica any more.” Other influences include the dark electro-pop of Goldfrapp and Depeche Mode, and the brooding mini-symphonies of Massive Attack.

Pop, however, works less well. “Most of the time there is no sadness”, says Steven. “It is too superficial,” adds Stijn. “We have tried doing Michael Jackson songs but it doesn’t work. And the more Madonna or Robbie Williams we go, the more likely we are to fail”.

The inspiration to do rock songs came to Steven in 2001 after a friend in London sent him a Radiohead CD, with some recordings the band had done for the radio station XFM, including a live version of Creep. “There was something so touching and emotional in his performance.” Scala & Kolacny Brothers had already been going for a number of years – the brothers had formed the choir in 1996 and it became successful in their native Belgium, where it was voted Choir of the Year for 1999-2000. But it was a traditional, classical choir, “performing for older audiences” says Steven, which was “very nice, but you always play the same old music again and again. It’s like cover versions – there are a trillion cover versions of Beethoven’s Fifth Symphony. And I didn’t like the feeling much, so that’s why I started making my own music”.

Stijn took some persuading – he was worried that the classical press would see Steven’s “indie-rock choir” idea as a cheap gimmick. And his fears appeared well founded when the brothers expanded their repertoire to include their new songs in traditional choir competitions – they were disqualified from one for using “bad language”. But before a backlash could begin, interest in their music soared in the rock press and on the radio, leading to a record deal with PIAS in 2002; their debut album, Scala on the Rocks, went gold within weeks of its December 1 release.

In its new indie-rock incarnation, Scala & Kolacny Brothers found fame in France and Germany, releasing albums in French (Respire in 2004) and German (Grenzenlos in 2005). In 2006 they signed to EMI and launched their own record label and production company, Fratelli. They have released two albums on Fratelli, including a Belgium-only release in 2008, Paper Planes, of original songs written by Steven. Steven even had a club hit with a dance music track, I Fail, he recorded with the Belgian DJ Regi. Scala & Kolacny Brothers tracks have become an unlikely club phenomenon, with DJs playing their songs as end-of-night anthems. To date they have released eight albums – but their new album is their first UK and US release.

Before Hollywood came calling, Scala & Kolacny Brothers’ music had already begun to infiltrate British and American TV. Their version of The Police’s Every Breath You Take has been used by ITV in a promotional clip for Downton Abbey; while in the States one of their original compositions, Our Last Flight, was featured in the FX biker drama series Sons of Anarchy.

Meanwhile, their live act has evolved into a formidable multimedia experience featuring custom-made video projections, animation, light shows, electronic sampling. The girls’ headset mics allow them to move freely onstage or even mingle among the standing audiences, “and that’s really powerful”, says Stijn. They attract a far more varied audience than they did in their classical days – now classical fans young and old mix with rock fans and indie kids.

They now travel like a rock band, in three tour buses. And they continually reinvest in the latest technology for their live shows – audio and video equipment, new film clips; even the buses themselves are state-of-the-art.

Gig venues can be anything from churches to rock venues for a couple of thousand fans to huge outdoor performances and music festivals. They have played to 50,000 people in Germany, and 40,000 last year in Quebec; they have also performed in Russia and Japan. This year, they will debut at the Coachella and SXSW festivals in America.

“Can you imagine, all those young women on tour?” laughs Steven. “It’s pretty much rock’n’roll – so you need to have discipline or after a few dates you will have singers being ill.” Having a large roster helps. “It took years to learn our lesson, but now we ensure there are always other singers available.”

The brothers attribute their success in part to their hometown of Aarschot (population: 15,000). Surrounded by woodland, it is a pretty, historic town with a flourishing café society. “We really like living here,” says Steven. “Life is good. And I am convinced that we were able to build everything we have because we started really small in a small town. It has been really important for us to grow slowly. We never had a commercial masterplan for success – what we do comes from the heart.”

The choir is the result of years of practice. The brothers both studied piano, Steven at the Royal Conservatory in Brussels, Stijn at Lemmensinstitute in Leuven. Steven graduated in 1992, nine years before his younger brother Stijn completed his education, the latter going on to study musicology at the K.U.Leuven University, “but I never finished my dissertation”. Steven taught music while he waited for his brother to finish studying, but “I wasn’t very good at it”, and so the brothers assembled an 18-girl choir on April 2, 1996 as a weekend project, to “do something creative”. It was years before they performed in public. And Steven only quit teaching after Scala & Kolacny Brothers had morphed into an indie-rock choir in 2002.

But even the brothers’ esteemed teachers didn’t spot their full potential. “The only examination I failed at Lemmeninstitute was choir direction,” says Stijn. “What a joke!” Scala & Kolacny Brothers’ subsequent Hollywood success, their spectacular bridging of the classical-rock divide, and their spine-tingling celestial performances have been the perfect middle-finger reply.