1921, not far from Paris — it is party day at Marguerite Dumont’s castle. Like every year, an array of music lovers gathers around a great cause at the owner’s place. Nobody knows much about her except that she is rich and that her whole life is devoted to music: Marguerite (Catherine Frot) sings. She sings wholeheartedly, but she sings terribly out of tune. Marguerite has been living her passion in her own bubble, and the hypocrite audience, always up for a good laugh, acts as if she is the diva she longs to be.When a young, provocative journalist decides to write a rave article on her latest performance, Marguerite starts to believe even further in her talent. This gives her the courage she needs to follow her dream. Despite the reluctance of her husband Georges (André Marcon), and with the help of a has-been divo, she decides to train for her first recital in front of a crowd of complete strangers.