Summer 1928, Montfort-l’Amaury, Sol and Rémi, brother and sister, 5 and 8 years old, inaugurate their new football. When Sol sends the ball so high that it lands on the other side of the wall, the two children enter the home of a strange character. Very quickly, a surly housekeeper named Mme Revéleau greets them with a verb as high as her bun: no one must disturb the master, who is busy working on his boléro. A Boléro? But what on earth is it? A chair? A hat? Consumed by curiosity, listening only to their courage, Sol and Rémi decide to investigate…