Mme de Lafayette wrote this during the reign of Louis XIV but the novel is set in the court of Henri II when his queen is Catherine de Medici, the young Mary Queen of Scots is his daughter-in-law and Diana de Poitiers was his mistress. As a courtier herself, Mme de Lafayette knew intimately the intriques and gossip that went on at court and she conveys that magnificently.
The young and very beautiful Madame de Cleves comes to court, is married rapidly to a man whom she admires and respects but cannot love, and falls in love herself with the Duke de Nemours, who feels the same for her. But tied by her sense of morality and the stories she has been told by her mother and others about the insincerity of court love, she restrains her passions and turns away from love.
This is a vivid, and exquisately written novel that turns on the small emotions of love, duty and passion lived out in a public court where everyone is watching everyone else, and no-one's secrets remain hidden. I read it in the French original and so cannot comment on the translation but it's difficult to imagine anyone not loving this book.