In 1856, fresh from life with nuns in an orphanage school, Alexina Barbin comes to a coastal village in La Rochelle to teach the village girls. She is deeply religious. She shares the classroom and a bedroom with the young and vivacious Sara, with whom she falls in love. Alexina has another secret: her gender is mysterious. She and Sara begin a scandalous love affair, but Alexina seeks marriage and social acceptance. She discloses her secrets to the village priest, to her mother, to the bishop, and to the bishop's physician. After the church and court rule on her petition, marriage to Sara becomes Alexina's sole purpose and hope.

Max, who dreams of adventures, abandons his studies at 18 to become involved in the navy. He becomes the sailor 512.

In this complex chronicle of the evolution of a provincial family's life, the story follows three generations of at least two neighboring families from the 1890s to the 1970s. In one of many related tales, a man who was engaged to the older daughter of a farmer elopes with the younger one. After many years and the birth of five children, the man leaves his wife and family for the bright lights of the city but continues turning up from time to time, until he is finally taken into the home of one of his sons when he is a quite old man. The complex interactions of the legitimate and illegitimate children of a womanizing miner give rise to yet another set of related stories.

A young man is checked into a mental hospital for unexplained reasons.