It is summer and debutante Rose is to be presented at Buckingham Palace. The family are at Grantham House, their London home, preparing for the busy social programme. Never one to miss out on such a grand occasion, Martha Levinson sails in from New York with Cora's recently disgraced brother Harold in tow. Both outspoken and larger-than-life, they create quite an impression amongst certain members of London's high society. When the Crawleys are implicated in a scandal that threatens to engulf the monarchy, Robert goes to great lengths to protect the royal family, as well as his own.