It is 1925 and Robert anticipates that he might have to cut costs, and reduce the size of the staff. Mrs Hughes is feeling nervous about being embarrassed when performing her wifely duties if she marries Carson.
The exchanges between Violet and Isobel over the hospital get worse. Cora sides with Isobel. Mary isn't happy with her father for offering Carson the servants' hall for his wedding reception, and offers upstairs instead. Mrs Hughes insists on a separate venue which causes some friction between the couple. Thomas starts to looks for a new job.
Violet attempts to get her son to support her view on the hospital merger and at a meeting of the Board things turn nasty. Edith has more arguments with the publisher of her magazine who walks out.
Lady Shackleton pays a visit with her nephew Henry Talbot, an old friend of Mary's. Sergeant Willis wants Miss Baxter to testify against the man with whom she was involved when she stole from a previous employer. Daisy becomes upset after she finds out that Mr Mason is unlikely to get Yew Tree Farm, and she decides to confront Cora, but she has already persuaded Robert and Mary to let him have the farm.
Neville Chamberlain becomes drawn into Violet's plan to save the hospital which results in some distressing consequences for everybody. Andy finds an unexpected confidante whilst helping Mr Mason. Edith meets Bertie Pelham in London. Spratt ends up helping Denker.
The house opened to the public to raise money for the hospital that causes tension amongst the family and the servants. Tension between Violet and Cora reaches boiling point as a decision is made about the hospital takeover. Carson is not happy with Thomas. Mary and Edith both hope to be able to overcome their past and find new happiness with the current men in their lives.
Henry's friend Charlie is killed in a crash. Mary decides to end things with Henry. Daisy and Molesley take their exams and Molesley is later offered a teaching job at the local school. Mrs Hughes pretends to have hurt her hand and gets Mr Carson to do everything which he makes a complete mess of and he gains a new respect for his wife's efforts. Mrs Patmore's B&B opens with its first guests. Bertie asks Edith to Marry him.
A change of circumstance leaves Bertie Pelham in the spotlight and and Edith needs to decide whether to hide her past or confront the truth and risk losing everything. Mr Molesley embarks on a career in teaching. Mrs Patmore's bed and breakfast gets some unwanted attention. Mary and Henry are reunited and are married.
Mary attempts to build some bridges with her sister but Edith and her secret continues to be a problem. Henry gets used to being a husband, but Charlie's death is hard to get over. Carson finds it hard to keep up with the changes. Spratt feels threatened by Denker's interference. Isobel is given some devastating news. Robert finds out how valuable it is to be independent. The staff and servants get ready to see in 1926 in with a unforgettable New Year's Eve celebration.