At the end of the 19th century, Valentine, aged 20, married Jules. Towards the end of the 20th century, a young Parisian woman crosses a bridge on her way to a party thrown by her cousin. There, she meets a young man. Later, she becomes his wife and the loving mother to their child. In the interim, between the two World Wars, two couples formed a quartet that was so close that after the death of one of the husbands and the wife of the other couple, the two families came together in a Paris apartment, 16 of them sitting round the table. A family tree, an eternity.