It is the 1950s and as the Duchy, the Cazalets' beloved matriarch, dies, she takes with her the last remnants of a disappearing world in which the Cazalets have thrived. Louise, now divorced, becomes entangled in a painful affair; while Polly and Clary must balance marriage and motherhood with their own ideas and ambitions. Hugh and Edward, now in their sixties, are feeling ill-equipped for this modern world; while Villy, long abandoned by her husband, must at last learn to live independently. But it is Rachel, who has always lived for others, who will face her greatest challenges yet.