The Guardian: No one can accuse Andrew Graham-Dixon of underselling his film The Secrets of the Mona Lisa (BBC2). He’s on the hunt for the truth about Leonardo’s masterpiece, embarking on an investigation that will take him on a trip around the world “with exclusive access and extraordinary encounters”. There will be revelations that “will change everything we thought we knew about history’s most enigmatic work of art”. And “all of this together marks an extraordinary moment in the history of art but, more than that, it is quite simply one the stories of the century.”

Bloody hell, bring it on, then; how does this story go? Well, once upon a time in Florence a man painted a picture of a woman. So far so not changing everything I knew (but then to be fair that is about all I knew). He was Leonardo da Vinci, no one’s disputing that; she was Lisa del Giocondo, the wife of a wealthy merchant… Or was she? Ah! See, now you’re interested, eh?

AG-D’s investigation takes him from Oxfordshire to Windsor Castle to Florence to Singapore to St Petersburg. He has exclusive access to documents and records, extraordinary encounters with professors and experts and other portraits which may or may not have been painted by Leonardo and which may or may not be this Lisa. She was painted by Da Vinci, that much seems clear, but that doesn’t mean she’s the 500-year-old lady in the Louvre, where she now hangs, providing a popular background for a 21st-century version of the self-portrait executed in the medium of mobile phone.

As far as I can see – utilising the medium of Google – this doubt about the subject of the painting has been going on for pretty much ever. But it gives Graham-Dixon a nice opportunity for international travel and the chance to demonstrate his own prowess with European languages.

But then, in Paris, it does get interesting, and new. A man named Pascal Cotte has developed a system of shining different wavelengths of light on to a picture to reveal what lies beneath and to see how it was created. He has been working on the Mona Lisa for 10 years; now for the first time he’s revealing what he’s found, peeling back the layers, layer-nado… stop it. Pascal, being French, compares it to peeling an onion. Or, if you prefer a more digital analogy, imagine LdV had done his picture4 on an iPad: it’s like going to the menu and selecting Undo Change or Restore Previous Session, something like that, to reverse not just the painting process but time itself. Got it?

Anyway, it’s fascinating. Suddenly here’s a bigger head and a bigger nose, beyond that another head, eyebrows, not smiling, looking over there. With his magic camera, Pascal has found a new face, inside the Mona Lisa. Who is she? Is she Lisa del Giocondo the merchant’s wife? But then, if so, who’s the enigmatic lady in the world’s most famous picture? The former lover of noble patron Giuliano de’ Medici? An idealised lady, a goddess? Or, as Graham-Dixon suggests, is it a work that transcended portraiture, and turned into an expression of everything Leonardo knew about nature and human nature? “So, the Mona Lisa isn’t really the Mona Lisa after all but something much more than that,” he concludes. “It’s a painting of life itself as Leonardo had come to think of it, his way of painting us all.” #JeSuisMonaLisa in other words. (Hey, Andrew – Andrea, André – I’m a bit of linguist myself…)

I don’t know about one of the stories of the century but it is a good one (it got better as it went along), well told, with a satisfying ending. I’m convinced, even if not everyone in the art establishment is. What does the Louvre know, anyway?