It's summer and as part of Rose's debutante `coming out' she is to be presented at Buckingham Palace. The family is in London, preparing Grantham House for the busy social programme, and Martha Levinson, not one to miss such a grand occasion, arrives from New York with Cora's recently disgraced brother Harold (Sideways star Paul Giamatti). Both outspoken and larger than life, they make quite an impression on certain members of high society. Meanwhile, when the Crawleys are implicated in a scandal that threatens to engulf the monarchy, Robert goes to great lengths to protect the royal family - and his own.