Downton Abbey (series 2)

November 1916. Matthew, now an Army officer, is fighting at the Battle of the Somme. He speaks of returning to Downton during his leave, which is coming soon. However, he tells the family that he is now engaged to Miss Lavinia Swire. When Lady Mary finds out, she attempts to hide her dismay and tells the other ladies that a Sir Richard Carlisle, a newspaper mogul known more for expediency than ethics, is coming to visit. However, when alone with Anna, she breaks down at the news of Matthew's engagement. Meanwhile the servants are preparing for a benefit concert to help fund the local hospital.

With Bates in London attending his mother's funeral, and Thomas serving in the Army Medical Corps, the servants are hard pressed to keep Downton running. A new housemaid, Ethel, has arrived, but constantly talks about improving herself and getting out of service, implicitly demeaning the staff. Most ignore her, but O'Brien dislikes her and repeatedly pulls mean-spirited pranks on her. Bates tells Anna that he may finally get a divorce and asks her to marry him. However, these plans are short-lived when Vera Bates arrives at Downton and threatens to expose Anna's part in Lady Mary's indiscretion with Pamuk unless Bates leaves with her immediately. He is forced to do so out of loyalty to the family, and Lord Grantham is furious at him for leaving with no notice or reason. However, Mrs Hughes has overheard Bates and Vera's conversation and informs Mr Carson of Vera's plot. Carson tells Lord Grantham this, and he immediately regrets his reaction to Bates' departure. Meanwhile, Sybil, eager to contribute to the war effort, leaves to begin training as a nurse. At her departure, Branson reveals his feelings for her.

April 1917: With many of the male staff away at war, Carson puts a lot of pressure on himself with the extra duties necessary to run the house to his exacting standard. He is forced to accept female staff serving in the dining room, something with which he is appalled. Lord Grantham hires Lang, newly discharged from the army, as his valet to replace Bates. O'Brien quickly notices manifestations of his shell shock, and is kind and helpful to him, complimenting his fine repair work on a suit. William is happy after receiving an important letter. Mrs Patmore receives devastating news about her soldier nephew; she had only known that he had died, but Lord Grantham finds out that he had been shot for cowardice.

Thomas returns from the war after being discharged from active duty due to his hand injury, which he purposely allowed to occur, and begins working with Lady Sybil in the local hospital. Thomas is attracted to a young lieutenant suffering from gas blindness who is overwhelmed and psychologically in extremely precarious condition. Over time Lady Sybil's and Thomas's kindness helps to pull him slightly back towards hope. Unfortunately, when he is physically stable, in spite of all their protests, Dr Clarkson (now Major Clarkson) orders the lieutenant's departure to complete his recovery elsewhere; every bed is needed at the hospital for the critically ill. That night he commits suicide. This event leads to the consideration of using Downton as a convalescent home. Molesley takes an interest in Anna, but she makes it clear that her heart will forever belong to Bates. Matthew learns he will be temporarily transferred back to England for a recruitment drive; the family is happy, but he is uncomfortable with the idea that he is safe while others are fighting. Carson advises Lady Mary that she should tell Matthew she loves him before it is too late. Meanwhile, Lavinia (Matthew's new fiancée who is staying with Mrs Crawley) is reunited with an unwelcome face from her past.

July 1917. The village hospital is not large enough to accommodate the large influx of wounded soldiers coming back from the front, so Downton is turned into a convalescent home. O'Brien is shocked that Isobel Crawley seems to be giving most of the orders while Cora is relegated to the background and suggests that Thomas might be able to aid her from his position at the hospital.

Early 1918: Ethel continues flirting with Major Bryant; when Mrs Hughes discovers them in the act of making love, she fires Ethel. Later, Ethel returns and admits she is pregnant with Bryant's child. Preparations get under way for a concert at Downton. Tensions flare between Isobel and Cora, Edith receives worrying news about Matthew and William, and Branson declares his feelings for Sybil again.

Mid-1918: Lord Grantham receives shocking news from the front; both Matthew and William have been wounded in France. Unfortunately, William has sustained serious damage to his lungs and will not recover, prompting him to ask Daisy to marry him before he dies. Meanwhile, Matthew has suffered a serious spinal-cord injury and is paralysed from the waist down. He is told that he will never walk again or father children. Lavinia insists that this changes nothing and that she only wants to care for him. However, Matthew tells her to forget him and sends her away, while Mary attempts to nurse him back to health. Carson and Mrs Hughes hire a new maid, Jane, despite her being a war widow with a child. Mrs Hughes has also been secretly helping Ethel and her baby since Ethel's lover, Major Bryant, has ignored her pleas.

October–November 1918: A Canadian officer, badly disfigured by burns, asks to be brought to Downton, claiming a relation to the family. Lord Grantham agrees, assuming he is some distant relation sharing common ancestry, but he stuns everyone by declaring that he is Patrick Crawley, the supposedly deceased heir. His story is that he survived the Titanic disaster but suffered from amnesia so he was unable to identify himself and lived as a Canadian until a wartime experience restored his memory. Most at Downton vehemently deny that possibility even though he recounts many details that only Patrick is likely to have known. Edith believes him, growing attached to him as he claims that he was always in love with her, rather than Mary. But, Lord Grantham's investigation casts doubt on the Canadian officer's claim, revealing that Patrick Crawley had a friend who emigrated to Canada. This leads to the burned soldier's sudden departure; he leaves behind a note for Edith that is deliberately ambiguous as to his identity.

Meanwhile, Matthew is getting used to his condition and Mary constantly caring for him; this displeases Sir Richard Carlisle. Carlisle and Cora conspire, to Lord Grantham's disgust, to bring back Lavinia, who resolves that she will never leave Matthew. Cora is worried about Isobel's aggressive management of Downton Abbey as a convalescent hospital until Violet slyly directs Isobel to the plight of refugees as a cause that has greater need of her nursing skills than the convalescent duties. Ethel hears the distressing news that Major Bryant has been killed. Carson debates whether to accept Sir Richard's tempting offer to leave Downton and be the Carlisles' butler after Sir Richard's marriage to Lady Mary; at the same time, Sir Richard makes it clear to Mary that he is uncompromising. Lady Sybil receives an ultimatum from Branson regarding his marriage proposal to her.

1919: As the residents try to return to normal life following the armistice, Matthew begins to be able to feel his legs. One day, seeing Lavinia drop a heavy tray, he suddenly gets up from his chair. Major Clarkson admits that he knew of this possibility from another physician but was sceptical about it and did not want to raise false hopes. Matthew announces that he and Lavinia intend to be married soon. Violet informs him that Mary is still in love with him, but Matthew feels obliged to marry Lavinia since she was prepared to sacrifice her life for him. Meanwhile, Sir Richard Carlisle distresses Anna by asking her to spy on Mary; his behaviour leads Carson to reject his offer of employment.

April 1919: As preparations are under way for Matthew and Lavinia's wedding, Lady Sybil's expressed wish to marry Branson shocks and horrifies her parents. Lord Grantham is strongly opposed to the idea but his threats of social disgrace and disinheritance do not dissuade Sybil. Grantham attempts to bribe Branson, but Branson's intentions are sincere, and he refuses. Lady Grantham, Carson, and Lavinia are taken ill by the Spanish flu. Thomas' black market venture was a spectacular failure, leaving him penniless and without a job, but Carson's illness gives him a chance to become useful in the house. Matthew finds himself alone with Mary and tells her what Violet said to him. Both acknowledge that they cannot marry, as it would be terribly cruel to Lavinia. However, they kiss just as Lavinia is coming down the stairs. When her illness delays the wedding, Lavinia tells Matthew that she heard and saw everything. She feels they should end their engagement but Matthew refuses. Fearing that Lavinia's illness might bring together Matthew and Mary, Richard Carlisle comes to Downton Abbey.