NOTE: This spoiler was submitted by Micah
In the opening scene, the iconic theme plays while a letter is signed and sealed in Buckingham Palace. The letter is then couriered by footman through the royal mailroom, onto a train through the English countryside, to the post office in the village of Grantham. It is finally delivered to Downton Abbey where the Earl of Grantham (Hugh Bonneville) announces that the King and Queen will be coming to Downton for one night to visit, as part of their Yorkshire tour. There will be a luncheon, parade, dinner, and a ball.
As the news and excitement spread throughout the household, we see that Lady Mary (Michelle Dockery) is running the estate. Lady Mary’s new husband, Henry Talbot (Matthew Goode) is in Chicago for a car show and will not be able to return immediately for the royal visit. Tom Branson (Allen Leech) is still a Republican (anti-monarchist). Mr. Thomas Barrow (Robert James-Collier) is now the head butler, kitchen maid Daisy (Sophie McShera) is unenthusiastic about the royal visit as well as her engagement to footman Andy. Lady Edith (Laura Carmichael) is busy running her own household, and Mr. Carson (Jim Carter) is retired to his own cottage with Downton housekeeper Mrs. Hughes who reminds him, “you’re not in charge there anymore.”
We see a known man traveling to Grantham on the train, entering a hotel, and later going to the car shop now run by Branson and Talbot. He questions Branson’s political leanings, and we are led to believe that perhaps Branson and his Irish background and anti-monarchist political sensibilities are seen as a threat to the royal visit. Branson reassures the man that he is loyal to the Crawley family if not the King.
At the palace, we see Queen Mary (Geraldine James) speaking with her royal attendant Lady Bagshaw (Imelda Stauton) about the visit. Lady Bagshaw asks if perhaps she could not go to Downtown with the Queen and reveals the Earl of Grantham is her cousin and closest male relative, and that Lady Grantham (Maggie Smith) assumes that he will be her heir. She insinuates that she has other plans.
Preparations are in full swing, and tensions are high. When Barrow shows too much deference to the opinion of the royal servants, Lady Mary grows concerned that Barrow is not up to the task of head butler and goes to Carson and asks him to come back and resume his duties for the royal visit. Carson agrees, and Barrow is understandably offended and refuses to be part of the preparations at all. He decides to go into town with a new acquaintance from the royal service.
When the King’s chef, butler, and housekeeper arrive in advance of the King and Queen, the Downtown staff are disappointed to learn that they are being pushed aside in all aspects of service (cook, footmen, butler, maids, etc.) in favor of the royal staff.
Branson meets Lady Bagshaw’s maid, Lucy, and they form a connection over understanding that awkward place between being considered a servant versus part of the family.
Preparations continue to deteriorate. The boiler goes out. A plumber has to be called in to fix it. There seems to be a spark between Daisy and the plumber which upsets footman Andy so much that he intentionally breaks the boiler again after it is fixed the first time. Ms. Patmore hates to disappoint the grocer that he will not be supplying dinner to royalty after all. Several things of value start disappearing. Chairs have to be ordered for the parade and set up in the pouring rain. The family is informed of the tension between Lady Grantham and Lady Bagshaw over the inheritance and Lady Grantham’s plans to confront her about it during the visit.
After the initial luncheon with the King and Queen, Lady Mary’s maid Anna (Joanne Froggatt) and Mr. Bates (Brendan Coyle) present the staff with a plan to push the royal servants out of the way, so that they can serve the royalty themselves and “restore Downton’s honor.”
At the parade, Branson, with Mary’s help, foils an assassination attempt on the King by the man Branson had previously thought was keeping an eye on him but was using Branson to get information about the exact location of the King.
Before dinner, the staff works together to lure the royal footmen away to London, drug the royal chef with sleeping pills, and lock the royal butler in his room, so that they can prepare and serve the meal to the King and Queen. The meal is a great success, so much so that the King sends his compliments to his staff, and footman Moseley can’t resist piping up and announcing that it was not the royal chef who prepared the meal but Ms. Patmore and the Downton staff who served it. His faux pas is graciously overlooked by the Queen and King.
The King asks Bertie (Edith’s husband) to accompany the prince on a several-month long tour with the prince. He accepts before Edith has the chance to tell him that she is expecting their first child and doesn’t want him to be away at the birth. He tries to get out of it, but to no avail.
While in town, Barrow goes with a stranger he met in a bar to a secret gay club only to have it raided by police a few minutes later. His new friend from the royal service manages to get him out of jail. Before he departs, Barrow asks if he can write him and says he feels like he finally found a friend. He responds, “Only a friend?” and kisses Barrow.
Anna confronts the Queen’s maid about stealing all the things that have gone missing and demands that she return them and fix Lady Edith’s dress which requires significant alterations in order to fit before the ball the next night in exchange for not reporting her.
At the ball, all is resolved. Mrs. Merton (Penelope Wilton) convinces Lady Bagshaw to reveal to Lady Grantham that Lucy is her daughter and that is why she wants to leave her estate to her maid instead of the Earl of Grantham. Lady Grantham is relieved that Lucy is not a conniving swindler and starts making plans to get Tom Branson to marry Lucy and restore the estate to the family.
Lucy and Tom seem more than happy to go along with everyone’s plans. Tom asks Lucy if she would like to correspond and offers “his shoulder” in her transition from maid to heir and they are shown dancing together out on the terrace.
The King tells Bertie that he doesn’t need to go on the trip with the prince after all so he can be home for his child’s birth. We shortly discover that Cora Crawley (Elizabeth McGovern) brought about that change of heart. “He asked the king, but I asked the queen,” she tells Edith.
Princess Mary decides to stay in her loveless marriage after exchanging some wise words with Tom Branson (who didn’t realize who she was at the time) about deciding what is most important.
Daisy discovers with Andy’s passionate response to his jealous over the plumber that they do in fact, have something in common and that she will move forward in marrying him.
Finally, Lady Mary comes to a resolution with her doubts and fears about continuing the efforts to keep Downton going after having a heart-to-heart with Lady Grantham. Lady Grantham reveals she doesn’t have much longer to live, but she knows that Mary will do a fine job in carrying on her legacy. As Mary swirls around the dance floor with her husband Henry, they both reaffirm that they are “stuck” with Downton.
In the final scene, Mr. Carson and Mrs. Hughes leave through the front door of the Abbey, stating that it will be alright this once. As Mrs. Hughes wonders about the future, Mr. Carson comments that 100 years from now Downton Abbey will still be standing and the Crawleys will still be living there.