This documentary traces the history of one of Edouard Manet's last works, "L'Automne", an unfinished masterpiece, now kept in the Musée des Beaux-Arts in Nancy. At the end of his life, Edouard Manet embarked on a pictorial project on the theme of the four seasons. To represent "Autumn", the painter chose Méry Laurent as his model. We look at this young woman of modest origins, sold at the age of 15 by her mother to the governor of the city of Nancy. She quickly became the mistress of Dr. Evans, Napoleon III's very rich dentist, and saw a whole artistic world open up to her. Méry Laurent visits the studio of Édouard Manet, who is already famous for his scandalous paintings. The young woman immediately falls under the artist's spell and becomes one of his favourite models... The investigation continues the trail of the other paintings in the 4 seasons series. First to the Thyssen Museum in Madrid to try to unravel the mystery of "The Amazon", a painting that could well represent "Summer”. And then to New York, behind the scenes of an exceptional auction at Christie's of "Spring", estimated at 32 million dollars.