Seeing recovered footage of Rudi Kurniawan in his wine-swirling heyday is laden with dramatic irony. Behind his affable, easy-going nature - bidding keenly at auctions, toasting his fortune with friends, joking that his wine is corked - he was all the while duping everyone around him. Meanwhile, anyone watching this unfold in the new feature-length documentary Sour Grapes soon knows that his deceit will be discovered, that he will be sent to jail, and that the scale of his crimes will disrupt the insular world of fine wine in which he operated.

The story may be familiar to wine's inner circle, but very few people are aware of how the whole story played out from his sudden emergence in the early 2000s to his dramatic demise and eventual incarceration over a decade later. In Sour Grapes, the filmmakers cover the entire span of the affair.

One of the film's best qualities is the deftness with which it handles the subject matter. The rarified world of wine is never dumbed down, nor is it pilloried for its excesses. Editorially, the narrative is non-judgemental, letting the characters on screen reveal themselves and allowing the audience to decide who deserves sympathy and who deserves none - something that is not as straightforward as you might imagine.

The quality of the interviews - which includes all of the most important players in the case, apart from Rudy himself - is another great strength, as is the acumen of the editing. Most of what is shown keeps the plot moving at an energetic pace, with just enough extraneous detail - from intruding pet dogs to backseat wine tastings - to give colour and dimension to all the participants.

From wry humour to revulsion to pathos, the film also conjures a gripping range of emotive reactions. The circumstances are far from black and white, and the film poses as many questions as it answers. Indeed, it could be criticised for failing to pursue some of the big unanswered questions that still remain from this case - but the director has stated that they didn't intend to solve anything, but to document the facts of the matter.

Finally, the production value of Sour Grapes deserves credit - the soundtrack, animation and photography all give the film an entertaining and light-hearted tone without undermining the seriousness of the subject.

The canon of great wine films isn't a huge category, but there's no doubt that Sour Grapes has a well-deserved place among the very best.

Sour Grapes is on limited national release now - check the website for details - and will be available on Netflix within a month or so.

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