The “Florentin”, a fabled, 137-carat yellow diamond last seen in 1918, has resurfaced and is up for sale at an exclusive Antwerp auction house. Simon (Yvan Attal), a thief recently released on parole, is bullied into taking on the most intricate and riskiest theft of his career. To succeed, he must get close to Julia (Bérénice Bejo), a beautiful diamond expert, for whom the sale is of considerable personal importance.

Simon starts to assemble the pieces of his elaborate ruse, suspecting that he is just another piece of someone else’s complex jigsaw puzzle. But when no one is who they appear to be, the streetwise don’t make their move until the last mask comes off. And beyond the boldly daring theft, Simon will lead Julia toward a destiny that she could never have imagined.