- Writers: Julian Fellowes
- Stars: Allen Leech , Brendan Coyle , Dan Stevens , David Robb , Elizabeth McGovern , Hugh Bonneville , Jim Carter , Joanne Froggatt , Kevin Doyle , Laura Carmichael , Lesley Nicol , Lily James , Maggie Smith , Michelle Dockery , Penelope Wilton , Phyllis Logan , Raquel Cassidy , Rob James-Collier , Siobhan Finneran , Sophie McShera
1923. A year has passed and Edith returned from Switzerland having secretly had her baby and given her up for adoption. The family and staff journey to London for debutante Lady Rose to be presented to the king. Martha Levinson and her son Harold also turn up and Mary meets both Anthony and Charles, who openly vie for her attention. Rose goes to a club with married friend Freda Dudley-Ward, from whom the cardsharp Sampson steals a love letter from the Prince of Wales. Mary and Charles endeavour to retrieve it in vain, though the escapade brings them closer. John is called upon to help obtain it. Mary is annoyed to learn from Anthony that the supposedly-republican Charles is himself an aristocrat's heir. Mrs Hughes and Mary discover that John was indeed in London on the day of Green's death. Martha attracts gold-digging admirer Lord Aysgarth but sees through him and turns down his proposal, though Harold, to his surprise, charms Aysgarth's daughter Madeleine and the Levinson valet Ethan is completely smitten with Daisy. The Levinsons want her as their cook. Back at Downton Edith hears that Michael has been imprisoned for opposing Hitler and seeks Tim Drewe's help in getting her daughter back.