Dundee duo caught LA on the hop

Rejected in London, two Scots posed as Californian rappers and ended up partying with Madonna

Rappers adopting a stage name, is nothing new. Think of Snoop Dogg or P Diddy. But for some a name change, or straight out lie, is nothing: no price is too great for the fame they crave. They will change the way they look and sound, alter their nationality and even their personality.

Take Billy Boyd and Gavin Bain: in reality, a couple of Scottish students from windswept Dundee – a city best known for its fruit cake – and a world away from LA. Angered at the sneering from London record industry executives searching for the British Eminem, the duo set out to fool the music business into believing that they were brash Californian rappers. Astonishingly, the plan worked.

The deception began after a disastrous audition in London in 2001. Speaking in a new documentary, Mr Bain, aka Brains, describes how "the vibe just changed horribly" the minute they started "talking in a Scottish accent". Getting nowhere fast, Mr Boyd, aka Silibil, adopted an American accent as a joke, and the lie began. "Out of spite we decided to develop these characters and that's when Silibil 'N' Brains were really born."

Taking their inspiration from MTV music videos, they prepared for "the biggest role that we'd ever play". The Great Hip Hop Hoax, which has its world premiere in the US on Thursday, tells the story of their rise and fall. By 2003, the duo were back in London with a spot at a music industry showcase. A management deal followed and they soon had a six-figure recording contract with Sony. Tipped as the "next big thing" by MTV, they played with Eminem's D12 band at Brixton Academy, and partied with Madonna and Green Day.

Their plan was to make it before coming clean, to show that if you have talent, your nationality shouldn't matter. But in the world of hip hop, which is all about "keeping it real", they forgot who they really were.

They lived in constant fear of being exposed. "We believed that if we got found out that we'd have to pay all the money back …. We didn't know if we'd go to jail for fraud," said Mr Bain. "We completely forgot that we were Scottish... I was definitely going a little cuckoo." They were trapped – never releasing a record in case their lies were exposed.

"It drove us from being best friends to hating each other," Mr Boyd recalls. Things came to a head in June 2005, when the pair had a furious fight. The next day Mr Boyd returned to Scotland. There was no big announcement and no outcry, as they had never released a record.

But his old friend struggled to adjust. His sister found him in her London flat after he had taken an overdose of painkillers. Now 31, Mr Bain is still living in London and waiting for his big break. Mr Boyd, now 32 and married with two sons, works on an oil rig in the North Sea.

But in recent months they have become reconciled. They will finally release their first album, Dirty Rotten Scoundrels (a self-funded record), later this year.