Mary is still inconsolable six months after Matthew's death, Edith supports Michael going to Germany to divorce his wife, Molesley looks for a job, and there is a surprise applicant for Ms. O'Brien's job.
An unofficial will from Matthew comes into the family's hand, Thomas plots against Anna, Rose gets involved in a scrap at a servant's dance, and Mrs. Crawley tries to reconcile Carson and Trigg.
An extravagant house party at the Abbey gives the Crawleys a chance to reconnect with old friends, but some guests prove more welcome than others, and along with the celebrations come deceit and heartache.
Anthony Gillingham returns to Downton to propose to Mary, Edna tries to coerce Tom into marrying her, and Anna will not tell Bates what's bothering her.
Mrs. Hughes tells Bates an edited version of Anna's rape, Edith goes to London to see Michael, Alfred takes a culinary test, and the Countess suspects new employee Pegg of theft and Robert tries to keep a tenant.
A birthday party is planned for Robert, but Rose's contribution to the event surprises those above and below stairs, a new farming venture on the Downton estate comes with dramatic repercussions for Mary, and Edith receives troubling news.
Cora's playboy brother, Harold, is in trouble, so Robert must travel to America to help bail him out; a new farming venture at Downton sees Blake and Mary putting aside their differences.
Rosamund comes up with a plan to help Edith, but Violet sees right through it; Isobel is the object of someone's attention, while Mary asks Gillingham for a very big favor.
Summer of 1923. It's summer and as part of Rose's 'coming out' she is to be presented at Buckingham Palace. The Crawley family go to London to prepare Grantham House for this busy social program.
