That evening at the Prado Museum, freezing weather had prompted visitors to return home before closing time. Except in the Velázquez room where a rather chic bohemian-looking couple had entered and surprised the guardian who, believing himself alone, was in full questioning in front of the Menins painting. "What could Velázquez paint on the painting in the painting? ".This enigma had obsessed him for so long, and in all likelihood it would remain so. It had been so for several centuries because no one had solved this mystery. The little that we knew about it came from a distant biographer whose interpretation was brought up to date in the sixties by the philosopher Michel Foucault and then definitively refuted by the art historian Daniel Arasse who ended up concluding in his eponymous work "We see nothing there". The enigma therefore had a bright future ahead of it, probably as long as the masterpiece existed, yes but ... that evening after closing, the curator discovers horrified that the work has just been vandalized in a very strange way. All the characters have disappeared from the composition as well as the mysterious painting. The following day the affair made the headlines of the press around the world.Then begins a long police investigation which leads the cops from Madrid to Sanlucar de Barrameda to an island from another time, that of the golden age of Spain. Will we ever know what Velázquez paints? ...