As Downton prepares for Edith's wedding to Sir Anthony Strallan, Robert and Violet are still lamenting her future as a nursemaid to a much older man. Thomas informs O'Brien and Alfred that he's hidden a couple of His Lordship's shirts in case any of them decide to walk off again. When Molesley mentions someone he knows is having trouble getting a job as a Lady's Maid, Thomas takes him aside to give him a tip about a possible opening that Miss O'Brien has not yet made known. Meanwhile, Carson overhears a conversation between Mrs. Patmore and Mrs. Hughes concerning her test results, which haven't come back yet.
The Granthams have made the hard decision to sell Downton. They have a house up north that is largely used for shooting and relaxing, resided in by a tenant now, but could be made into the family home. Cora wants to take everyone for a visit up there the next day when Molesley pops in to mention he has a suggestion for the replacement of Miss O'Brien whom he understands is leaving. Cora plays along, but admits, after Molesley leaves, that O'Brien has mentioned nothing to her about this. When Cora asks O'Brien if there's anything she'd like to tell her, O'Brien hasn't a a clue.
Cora is still not convinced something isn't up and is disappointed. Grantham has mixed feelings over it as moving to a smaller house will require a reduction in staff anyway. Mary suggests they wait until after the wedding to plan how to tell the servants of their predicament.
Carson meets up with Dr. Clarkson on the street, implies he knows more than he does, but only gets Clarkson to tell him that getting Mrs. Hughes more rest would be a good thing. Then Carson uses his meeting with Clarkson to manipulate Mrs. Patmore into admitting that Mrs. Hughes is waiting on testing to determine if she has cancer.
Robert admits to Sir Anthony that he's still concerned about his daughter marrying a man the same age as her father and with an infirmity to boot. Sir Anthony understands all of these concerns and asks if Grantham is happy about the marriage. Robert diplomatically admits he wants his daughter to be happy and that Anthony intends to make her happy, but he stops short of blessing the union.
Carson, noting how busy Mrs. Hughes is planning for the wedding, urges her to let him help her if she gets tired, denying he knows anything he shouldn't.
At her center in York, Mrs. Crawley is teaching sewing to the prostitutes who are more interested in the food that is provided when Ethel appears again. Isobel approaches her, encouraging her to accept help, but Ethel scurries off again. When she returns to Downton, Isobel asks Mrs. Hughes for Ethel's address.
The day of the picnic, Swire's lawyer gives Matthew not only the death certificate of the second heir, but a letter written to Matthew by Reginald Swire. He refuses to read the letter as he's certain that it's full of praise that he doesn't feel he deserves. As they are ready to leave to view the much smaller house her family will be relegated to thanks to her husband's guilty conscience, Mary takes the opportunity to remind him again how much pain her family could be spared if he would just accept the money.
The entire family, including Isobel and Sir Anthony are traveling to the alternate house up north. Before their departure, Carson expresses his concern to Cora that Mrs. Hughes may be seriously ill and asks that some of her work be given to him. When Cora also mentions Molesley told her O'Brien's leaving, Carson is surprised.
Anna is in London to meet with Mrs. Bartlett, the friend of Mrs. Bates, who accepts her money but claims she has nothing to say. Anna only wants to know if Vera Bates was unhappy enough to commit suicide. Mrs. Bartlett readily admits that Vera was unhappy that her husband had run off with another woman. She takes Anna inside and explains how Vera feared Bates in the end. On the last day she saw Vera alive, the two of them walked to the post office together, Vera had been baking a pie, nervously rubbing her fingernails and expressing her fear of her husband. She remembers Vera walking toward her house, the evening gas lights creating a halo effect over her. Despite her tough exterior, it's clear Mrs. Bartlett is distressed over the death of her friend.
In prison, Bates is warned by a fellow inmate that Craig is setting him up. Later, while Craig sleeps, Bates searches his bunk for anything incriminating, even as the keys of the approaching guards are heard rattling nearer and nearer. He finally finds something pressed between the bunk and the wall just in time for the guards to come in. Both cellmates are stood against the wall while the bunk is searched. Bates, with the object on his person, is not searched and the guards leave, having found nothing.
The new home, which they talk of renaming Downton Place, is smaller than the current house, but can be run on a much smaller staff.
At Downton, Carson asks O'Brien why Mr. Molesley thinks she's leaving. She denies it and goes to Lady Cora to clear up the confusion. Cora accepts that O'Brien isn't leaving, but is certain she must have said something that Molesley misinterpreted. Molesley admits that Thomas told him the news, so O'Brien makes sure Thomas knows that he'd better watch his back.
Cora also assures Mrs. Hughes that, if she is sick, she needn't worry about her future. She promises that a nurse will be gotten to care for her here at Downton. Mrs. Hughes is genuinely touched by the kindness.
Mary upsets Matthew by admitting that she read Swire's letter and tells him that Lavinia had, apparently, sent her father a letter the day she died, telling him how she'd tried to release Matthew from his commitment to her, but he'd refused. She asked him to look after Matthew if something happened to her. Swire's letter assures him that he is adding him as a possible heir with full knowledge of the truth. Matthew will not budge on his conviction that taking the money is wrong, especially since it can't be proven that the letter is really from Swire and that there is no evidence Lavinia sent her father a letter that day.
Mary goes to the staff downstairs and asks if any of them sent a letter. None of them know anything until Daisy appears and admits that Lavinia had got to talking to her when she came in to start the fire. She had taken a letter to post for her.
On the day of the wedding, Carson is still fretting over Mrs. Hughes. Mary tells Matthew that she has proof that Lavinia did send a letter the day she died which is good enough evidence for her that Mr. Swire's letter is genuine and Matthew needs to stop coming up with excuses not to take the money. Matthew agrees, but does suggest they wait to tell the family after Edith's wedding.
While the photographer takes a picture of the three Crawley daughters, Sir Anthony is looking unwell inside the church. The vicar barely gets into his ceremony when Strallan stops him and admits he cannot do this. He apologizes profusely to Edith, but he believes this is a mistake. Robert, still at his daughter's arm, tries to tell him it's too late to look back now. On the other hand, Violet steps up, takes the confused and upset Edith and tells her that she needs to listen to what her intended is saying. Sir Anthony rushes out, distraught, leaving Edith to go home, race into her room and collapse on her bed.
Her mother goes to comfort her, telling her that she's being tested and will come out of it stronger.
The Granthams make sure the servants know to get all the decorations down and the wedding food out of sight. Most of the food will be taken to the church for the poor, but some of what won't keep is enjoyed by the servants that night. Most of them are sympathetic toward Edith and even Carson will allow a little criticism of Sir Anthony at the table. Daisy wonders if the newfangled emphasis on women's rights is a good thing. Anna believes the vote will happen, but it will be a long time before men will accept women pursuing them instead of the other way around. Since Daisy is rather interested in Alfred, this interests her.
Matthew takes Robert aside and tells him that he has indeed inherited the Swire fortune and would like to offer it to Robert so that Downton can be saved. Robert refuses to accept the money, but ultimately decides that he will only if Matthew agrees it's an investment. Both of them will run the place until the day when it becomes Matthew's entirely.
Isobel suggests that Edith be given something to do to take her mind off of her worries. Anna tries to help her, but Edith has determined that she's doomed to be a spinster.
Mrs. Hughes goes to her appointment, returns and Mrs. Patmore indicates to Carson that the lump is benign. After she assures Mrs. Hughes that she's put Carson out of his misery, Mrs. Hughes hears the butler singing happily while he polishes the silver.