The world’s biggest wine forger started small. It was the early 2000s, and a young man who went by the name of Rudy Kurniawan began to make a name for himself on the Los Angeles scene. He had swept-back hair and a hearty laugh. More importantly, he had pockets of seemingly infinite depth, so his new friends overlooked his mysterious origins. It was said he came from a wealthy Sino-Indonesian family, living large off handouts. But nobody pressed too hard as long as the dinners – and booze – kept flowing.

In one auction alone in 2006, Kurniawan sold $24.7m of wine

Kurniawan also had a palate of rare finesse, better than most at identifying the characteristics of different vintages. Or at least, that’s what the people he fooled said. At first he was interested in Californian wines, in particular pinot noir, but soon developed a taste for Burgundy, made mainly from the same grape but far more glamorous. In Burgundy’s Byzantine system of appellations, Kurniawan sensed hard profits. He became a major player at auctions, buying – and selling –some of the 20th century’s greatest wines. He bought so much Domaine de la Romanée-Conti he became known as “Dr Conti”, which presumably later amused some of those he defrauded.

In one auction at Acker Merrall & Condit in 2006, Kurniawan sold $24.7m of wine, beating the previous record by $10m. These were the days of the first dotcom boom, when Silicon Valley had more money than sense, a combination which has always been drawn to fine wines.

Facebook Twitter Pinterest Corked: foil capsules, labels and corks that were used as evidence in the trial of Rudy Kurniawan. Photograph: Stan Honda/AFP/Getty Images

In time, however, discrepancies appeared in the market. Bottles of Clos St Denis from Domaine Ponsot, of vintages between 1945 and 1971, started to turn up. Laurent Ponsot, the head of the house, found this surprising as his family only started making the wine in 1982. He set out to investigate.

Around the same time Bill Koch, an American billionaire who found fake bottles in his collection, hired private detectives and filed a lawsuit. Authentication experts saw more and more dodgy consignments emerging from these record-breaking auctions. At last the FBI got involved. In March 2012 they raided Kurniawan’s house in Arcadia, California. They found a fully equipped counterfeiting workshop, complete with corking tools, labels, empty bottles and extensive tasting notes. Kurniawan had been taking cheaper wines – though still better than you will find in your average off-licence – and putting them in more expensive bottles, or altering bottles to appear more valuable.

The most expensive wines are so rarely drunk few can claim to be expert on how they taste. On the occasions they are opened, it is usually courtesy of a generous host. It is poor guestmanship to lob aspersions on any proffered bottle, let alone one that cost as much as your car. What’s more, several scientific studies have shown that even professed experts are hardly better than chance at identifying different wines. The entire industry hangs on the word of the critic Robert Parker, whose scores are a benchmark against how wines are priced. A Princeton economist came up with an algorithm based on weather data from the grape crop’s growth period that nearly exactly mimicked Parker’s scores.

Facebook Twitter Pinterest Caught red-handed: bottles being prepared att Kurniawan’s California home Photograph: pr

The feeling of being scammed will be familiar to almost anyone who has ordered wine in a restaurant: Kurniawan simply scaled it up. In 2014 he was sentenced to 10 years in a California prison, the first person to be convicted of wine fraud.

A new documentary, Sour Grapes, revisits the story. It came about after two directors met by chance at Kurniawan’s trial. Jerry Rothwell, an Englishman who had been working on a film about the founders of Greenpeace, was following Laurent Ponsot on the trail of his faked wine. Reuben Atlas, an American, was coming from the opposite view. Having read about the arrest in New York Magazine, and not being a wine buff himself, Atlas thought Kurniawan sounded like a Robin Hood figure, taking only from those who could afford to pay.

The FBI found a fully equipped counterfeiting workshop at Kurniawan’s house

“We were always at the back of the line for interviews in court, so we ended up talking to each other a lot,” says Rothwell. “Pretty quickly we worked out that we could work together, and given the nature of the story it was helpful to have someone in Europe and someone in America. It’s like the opposite of an Agatha Christie story, where there is one detective and multiple suspects. Here there were multiple detectives.”

The tale is told through a mixture of interviews and archive footage. A film crew had followed Kurniawan for a few days early on, for a pilot of a food and wine show that was never made. These scraps let us see Kurniawan as he must have appeared to the world he conned: boyish, charming, evasive. “Can we put the cork back in the bottle,” he jokes at one point. Knowing how his story ends, it is compelling, and very funny. Like Atlas, you cheer along as he toys with his new friends. One group calls itself the Angry Men because of the way they feel when they take a good bottle to a party and find everyone else has bought plonk. At Angry Men dinners, $200,000 might be drunk in a night.

Facebook Twitter Pinterest Spot the difference: three bottles of wine used as evidence in Rudy Kurniawan’s trial. The magnum dates from a time when magnums were not available Photograph: Stan Honda/AFP/Getty Images

Atlas and Rothwell tried in vain to secure an interview with Kurniawan. Once they knew they wouldn’t have time with him, the nature of the film changed. “It became a film about being conned, rather than the conman,” says Rothwell. Even then it wasn’t easy to get hold of the collectors: few want to admit they have been duped.

Ponsot was essential to Kurniawan’s unravelling. Unlike many in the wine community, he does not take himself too seriously. Above a well-kept grey and black beard, his eyes have a Gallic twinkle. He saves seriousness for the concept of Burgundy. “The fakes are like a piece of dirt on the name of Burgundy,” he says. “I wanted to wash it off.”

From the American end, the pursuit was led by Bill Koch, brother of Charles and David who run Koch Industries and are part of a vast oil and gas dynasty. With an estimated fortune of $2bn, Bill left the family firm and became a collector of sculpture, ancient Greek coins, model ships, real ships (his team won the America’s Cup in 1992) and impressionist art. Interviewed in front of a wall of Monets in his Florida mansion, he comes across like a teddy bear with a temper.

'Can we put the cork back in the bottle,' Kurniawan jokes

“I hate being cheated,” he says. “There’s a code of silence in the wine industry – I was not going to take it. With super-fine wines you can taste the love the vintner had in making it, and that to me is almost a religious experience. We collectors like precious things. What price can you put on love?” he says, before correcting himself. “Well, when you get divorced you can.”

“In some ways Bill had more resources than the FBI,” says Rothwell. Without Koch, the trial might never have come to pass. He hired Brad Goldstein, a private investigator who prefers beer and clearly finds the whole wine scene preposterous. Goldstein had spotted a magnum of Pétrus from 1921, a time when they made no magnums.

Those duped were almost exclusively male. These were men showing off, including Jay McInerney, the Manhattan literary enfant terrible who has mellowed into a wine critic. There is “Hollywood” Jef Levy, a red-nosed sunglass-clad producer of films you won’t have heard of. There’s a drawling suit-clad investor, swirling a glass in a taxi across town. “Buy ’06 Champagne,” he tells us. “If you can’t afford that, buy ’02. If you can’t afford that, drink fucking beer.”

It’s striking how easily those in the boys’ club were prepared to believe in the character of Kurniawan – an ingenue immigrant with plenty of cash, who wanted to be part of their gang. “Everyone in the story could play themselves in the Hollywood movie,” says Atlas. “They were all so perfectly cast: you pick up on who they are very quickly.”

The effect of the rogues’ gallery is that Kurniawan comes across as a more sympathetic figure. As with a diamond heist, you root for the plucky conman rather than the rich victims, and like any great forger, Kurniawan is a skilful artist himself. Part of the reason it took so long for the fraud to emerge is that as long as a bottle of fake wine is passed from cellar to cellar, nobody loses out. In one of those gleaming snippets of old footage, Kurniawan tells his fellow diners to beware of online auctions, where you can’t be sure of the wine’s provenance.

One expert suspects 80% of pre-1980 Burgundy is counterfeit

“When we started out I thought: ‘Here’s a guy who’s sticking it to rich people, and good on him,’” says Atlas. “But as I got to know the people involved, and understand the process of wine-making, I became less sympathetic. My perspective changed.”

Kurniawan’s was the first case of wine fraud to be successfully prosecuted in the US. But the government did not chase the paper trail back to Indonesia. There are signs he was not acting alone. Ponsot believes it would have been impossible for one man to produce so many counterfeit bottles, and also that wine fraud is a much bigger problem than has been acknowledged. In a recent interview he said he suspected 80% of the Burgundy allegedly from before 1980 is counterfeit.

“Rudy is by no means the only faker,” Rothwell agrees, pointing to the stories from France about “wine terrorism”, where a group of activists has taken to smashing up vineyards and storage facilities, partly out of fears over cheap Spanish imports.

Kurniawan’s family is tantalising, and in the far reaches of his story lie implications darker than the cellars of a few movie moguls. The investigators allege that Kurniawan’s real name is Zhen Wang Huang – “Rudy Kurniawan” is a compound of two famous Indonesian badminton players – and he was denied a US visa in 2003. The documentary traces his mother’s brothers, Hendra Rahardja and Eddy Tansil, back to an infamous bank fraud, where $800m was stolen and has not been recovered. Tansil is still at large, supposedly in China. In 2007 alone, Kurniawan wired $17m to his brothers in Hong Kong and Indonesia. And although email documentation shows Kurniawan was often desperately short of money, he still lived in a mansion and drove a Ferrari.

It’s clear that some of his friends from the wine world still don’t want to believe what Kurniawan did. Hollywood Jef slips between the past and present tenses talking about his old friend, incredulous that this could have happened. “I still don’t know whether Rudy got into wine and then saw an opportunity, or saw wine as the opportunity from the start,” says Rothwell. “Anything that depends on what people want to believe is a complex area.” When rich men want to spend money, they’ll find a way to do it, in other words. To prove the point, a market has already emerged for Kurniawan’s wines – both the unadulterated bottles in his collection and also the fakes that survive.

Facebook Twitter Pinterest Bad bottles: a magnum of Pétrus 1947 from the trial… only it isn’t. Photograph: Stan Honda/AFP/Getty Images

“Taste is obviously really subjective and contextual, and it’s hard to put into words,” says Rothwell. “But with wine it’s not as simple as saying it’s the emperor’s new clothes, or that this was a victimless crime. There are bigger questions of authenticity, which is why Ponsot is so important to the tale. This reaches deep into French soil and French history, and for him is quite abstract. Whether you’re into wine or not, it’s a story about human fallibility.”

Whose, though? Wine is meant to bring people together, in warmth, conversation and laughter. Beyond this we add history, mystique and science, mainly because they are fun. The spirit of wine frolics around naked; it is not a suited accountant. Few drinkers, as they uncork an £8 bottle from Tesco, think in terms of investment, or the authenticity of the bottle. Rudy Kurniawan broke the law, but Dionysus would surely have chuckled.

Sour Grapes is released on 16 September