Downton Abbey (series 2)

November 1916. Matthew, now an Army officer, is fighting at the Battle of the Somme. He is returning to Downton during his upcoming leave and informs the family he is engaged to Miss Lavinia Swire. Lady Mary attempts to hide her dismay, and announces that she has invited Sir Richard Carlisle, a ruthless, wealthy newspaper mogul to Downton. Later, alone with Anna, she breaks down over Matthew's engagement. Meanwhile, the servants prepare for a concert to help fund the local hospital.

With Bates in London for his mother's funeral and Thomas in the Army Medical Corps, the servants struggle to keep Downton running. A new housemaid, Ethel, irritates the other servants with her constant boasts about improving herself, causing O'Brien to repeatedly pull pranks on her. Bates tells Anna that he may finally be able to get a divorce and proposes. Vera Bates, Bates' estranged wife, arrives at Downton and demands that Bates return to her or else she will expose Lady Mary's indiscretion with Pamuk. Bates gives his notice without explanation, infuriating Lord Grantham. However, Mrs Hughes overheard Vera's demands and tells Mr. Carson, and he informs Lord Grantham.

April 1917: With so few male staff left, Carson overworks himself, until he collapses while serving dinner. He is forced to accept female staff serving in the dining room.

Lord Grantham hires Lang, newly discharged from the army, as his valet. O'Brien notices signs of his shell shock and is kind to him. William is happy after receiving an important letter. Lord Grantham informs Mrs Patmore that her nephew was shot for cowardice. Thomas, now discharged from front-line service, goes to work under Dr (now Major) Clarkson at the village hospital along with Lady Sybil. Thomas and Sybil help a blinded young lieutenant who is depressed by his future. But Dr Clarkson says that the lieutenant has recovered from his wounds and must be transferred to a different facility. The young man commits suicide. This tragedy leads to Downton becoming a convalescent home.

Molesley is interested in Anna, but her heart belongs to Bates. Matthew is unhappy about returning to England for a recruitment drive. Carson advises Lady Mary to tell Matthew she loves him before it is too late. Lavinia is confronted by Sir Richard Carlisle, an old and unwelcome acquaintance.

July 1917. Downton becomes a convalescent home for wounded officers, with Isobel taking charge, and the family confined to a relatively few rooms. At O'Brien's instigation, Cora gets Acting Sergeant Thomas Barrow assigned to run the military side of Downton.

Early 1918: Ethel continues flirting with Major Bryant; when Mrs Hughes finds them in bed together, she dismisses Ethel. Later, Ethel returns, announcing she is pregnant with Bryant's child.

Preparations are under way for a concert at Downton. Tensions flare between Isobel and Cora, while Edith receives worrying news about Matthew and William. Branson declares his feelings for Sybil again.

Mid-1918: Lord Grantham receives shocking news from the front; Matthew and William have been wounded in France. Matthew has suffered a serious spinal injury and is paralysed from the waist down. He is told that he will never walk again or father children. Lavinia insists this changes nothing and that she only wants to care for him. However, Matthew wants 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, though she is a war widow with a child. Mrs Hughes also secretly helps Ethel and her baby since Ethel's lover, Major Bryant, has ignored her.

October–November 1918: A Canadian officer, badly disfigured by burns, arrives at Downton. He stuns everyone by declaring that he is Patrick Crawley, the supposedly deceased heir. He claims he survived the Titanic disaster but suffered from amnesia and lived as a Canadian until his memory recently returned. Mary vehemently rejects the claim, but Edith is persuaded as "Patrick" recounts details of old times at Downton, where Patrick was a frequent childhood visitor. Robert has his solicitor Murray investigate; Murray learns that Patrick Crawley had a close friend who emigrated to Canada. "Patrick" abruptly departs, leaving a plaintive but ambiguous note for Edith.

Meanwhile, Matthew is adapting to his condition and Mary's caring for him, displeasing Sir Richard. Carlisle and Cora conspire, to Lord Grantham's disgust, to bring back Lavinia, who resolves that she will never leave Matthew.

With the war ending, Isobel is full of social-improvement schemes using Downton Abbey, alarming Cora. Violet distracts Isobel with the plight of refugees as a cause that has greater need of her skills. Ethel hears the distressing news that Major Bryant has been killed.

Carson debates whether to accept Sir Richard's 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 strive to return to normal life following the armistice, Matthew begins to feel his legs. One day, seeing Lavinia about to trip while carrying a heavy tray, he suddenly rises from the chair. Major Clarkson admits this was a possibility but did not want to raise false hopes. Matthew announces that he and Lavinia intend to marry soon. Violet tells him that Mary is still in love with him, but Matthew feels obliged to marry Lavinia. 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 wish to marry Branson shocks and horrifies her parents. Lord Grantham strongly opposes it but his threats of social disgrace and disinheritance do not dissuade Sybil. Grantham attempts to bribe Branson but he refuses. Lady Grantham, Carson, and Lavinia are taken ill by the Spanish flu. Thomas's black market venture fails, leaving him penniless and unemployed, 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. Both acknowledge that they cannot marry as it would be cruel to Lavinia. Lavinia overhears them and sees them kiss. When her illness delays the wedding, Lavinia tells Matthew that she heard and saw everything. She wants to call off the wedding but Matthew refuses. Fearing that Lavinia's illness might bring together Matthew and Mary, Sir Richard comes to Downton Abbey.