The director and some of the protagonists of the film were interviewed by Alexandre Duyck for this well documented article. [article in French]
Since 1934, a law has prohibited the sale of a handful of grape varieties for erroneous or spurious reasons. According to the detractors of the time, these grapes would drive people crazy. But, for a long time, the resistance has been organized to keep these cursed grapes alive more or less under the cloak. It could well be that in the next few years, they officially find their way back to the glass. Investigation.
[automatic translation]