Of all the douchebags on parade in "The Lost Leonardo," an art-crime documentary with no shortage of them, the douchiest might be Yves Bouvier, a Swiss scammer whose purpose in life, until recently, was to make himself indispensable to rich people in need of top-tier artwork in which to invest — and thus hide — their wealth. As we see in the movie, by Danish filmmaker Andreas Koefoed, this middleman function can be a good gig. In 2013, after two days of low-sweat scheming in Geneva, Bouvier walked away with a profit of $47 million. And apart from lying to everybody in sight, he felt that what he had done was just business as usual. Various tax authorities have disputed that.

What happened was, Bouvier made the acquaintance of Dmitry Rybolovlev, a dodgy Russian who became an insta-billionaire in the post-Soviet financial chaos of the 1990s. To shelter his sudden, enormous wealth from the tax people — to move it out of Russia and to keep it moving — Rybolovlev had decided to invest it in classic art. Yves Bouvier, an art dealer with roots in the business of tax-free warehousing (another shadowy art-world precinct covered in this entirely absorbing documentary), became his adviser. One day, Rybolovlev came to Bouvier and told him he wanted to buy a special painting he'd heard about: a portrait of Jesus called the "Salvator Mundi" — a "lost Leonardo," as it was being billed. Bouvier looked into this and, being a con man himself, was immediately suspicious. Paintings by Leonardo da Vinci, who died 500 years ago, are exceedingly rare — only about 15 are known to exist. A new one hadn't come to light in more than a century. So where was this latest one from?

Bouvier learned that the painting had turned up at an auction in New Orleans in 2005. There, two New York wheeler-dealers bought it for $1175, put it in a cardboard box and shipped it back to Manhattan via UPS. Since the picture was damaged and heavily painted over, it was dispatched to a top restorer named Dianne Modestini. In the process of cleaning and retouching the painting, Modestini came across a small area around Jesus' mouth that was exactly — exactly! — like one in Leonardo's "Mona Lisa." Soon she was moved to announce, "No one except Leonardo could have painted this picture."

This dictum launched the painting on its way toward a breathtaking later valuation of $400 million. However, not everyone agreed with Modestini (who profited financially from her assessment of the picture). "Most of the painting is a remake," one German Leonardo expert pointed out, while another described the work as "a masterpiece by Dianne Modestini." ("Absurd," Modestini responds here.) "It's not even a good painting!" hisses American art critic Jerry Saltz.

One of the film's most admirable virtues is the way in which it throws the negotiable ethics of the art world into high relief. In the area of Old Masters paintings, says Bank of America art-finance executive Evan Beard, "Opinions matter more than facts." Then we see Luke Syson, curator of Britain's National Gallery, describing a convocation of Leonardo experts he organized in 2008 — their response to the painting, he says, rather vaguely, was "very positive." Then we hear one of these experts, Oxford art historian Martin Kemp, expressing his positivity in a gush of art blather. "Leonardos have a strange presence," Kemp says of the painting. "They're very assertive, but also very ambiguous."

A salient fact about the purported Leonardo was that nobody wanted it. The New York owners offered it to a number of museums, but since the picture had no solid provenance (and was saddled with an asking price of $200 million), there were no bites. Eventually, it arrived in the hands of Yves Bouvier, who was subsequently crushed like a bug by his client Dmitry Rybolovlev after Rybolovlev learned that Bouvier had been inflating the prices of the artworks he'd acquired for the unwisely trusting Russian and keeping the overage for himself. Suddenly, Bouvier found that he was no longer getting callbacks from any of the many auction houses, banks and insurance companies he had long worked with, and that his assets had been frozen. In another context, it might have seemed sad.

And so, in 2017, the "Salvator Mundi" went up for auction at Christie's, in New York. The winning bid of $400 million was weighted with a $50 million commission charge. At first, no one knew who the winning bidder was, but before long it was revealed to be the Saudi Crown Prince Mohammed bin Salman, a grotesque individual (accused murderer, etc.) who reportedly has kept the painting somewhere on his ridiculously enormous yacht while waiting to put it on display in Abu Dhabi, at a satellite museum of the Louvre. Meanwhile, the painting is still an object of much contention in the West. Art-world gadfly Kenny Schachter says the picture was "nowhere near adequately vetted," and that it was always intended to be sold privately (perhaps never to be seen again). Jerry Saltz, the critic, calls the painting "a made-up piece of junk." Says another observer: "It's not about art. It's about money."