Valentin D. and Constance Brandt, a couple of fashionable architect designers are preparing the opening of their retrospective at the Palais de Tokyo. But what nobody knows is that in order to integrate into the world of Parisian design and luxury, Valentin lied about his proletarian and ch'tis origins. So, when her mother, her brother and her sister-in-law arrive by surprise at the Palais de Tokyo on the opening day, the meeting of the two worlds is overwhelming. Especially since Valentin, following an accident, will lose his memory and find himself 20 years back, more ch'ti than ever!