Set in October/November 1918. Mary wheels Matthew around the grounds of Downton. Richard Carlisle sees this while talking to Robert. Major Clarkson walks in and tells Robert a Canadian officer, badly disfigured by burns, asks to be brought to Downton, stating 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.
At Crawley House, Violet, Cora and Isobel discuss the quickly approaching surrender of the Ottoman Empire and the end of the Battle of Vittorio Veneto. Isobel suggests Downton continue be used in a useful way instead of remaining a private house, much to the shock of Cora and Violet.
Richard Carlisle shows Mary Haxby Park, who is shocked at how empty the house looks now. Mary is also dismayed at the fact that the family who formerly resided at Haxby was now packed up and gone. Carlisle asks if they should rescue Haxby.
Edith asks around if anyone has any more letters to post. Coming upon Patrick, he remains surprised at her not recognizing him. He shocks her upon revealing who he is. His story is that he survived the Titanic but suffered from amnesia so he was unable to identify himself and lived as a Canadian until a wartime experience restored his memory. Most of the others vehemently deny the possibility even though he remembers many details that only Patrick is likely to have known. However, Edith believes him, growing attached to him as he claims that he was always in love with her.
Matthew is getting used to his condition, constantly cared for by Mary but Sir Richard Carlisle is strongly displeased by her continued interest in Matthew. He and Cora conspire, to Lord Grantham's disgust, to bring Lavinia back who then resolves that she will never leave Matthew.
Ethel hears the distressing news that Major Bryant has been killed. Carson debates whether to accept Sir Richard's offer to be their butler after his marriage to Lady Mary. Lady Sybil receives an ultimatum from Branson regarding his love for her or staying at Downton Abbey. Bates is shocked to find his divorce threatened by Vera revealing that he paid her to leave him and he goes to London to make another attempt to settle matters with her. However, upon his return, he receives the news that she is dead. Lord Grantham's investigation casts doubt on the Canadian officer's claim, revealing that Patrick Crawley had a friend who emigrated to Canada, leading to his sudden departure, leaving behind a note for Edith that is deliberately ambiguous as to his identity.
The war ends with the November 11 Armistice not long after.
- Major Bryant was said to have been killed in the Battle of Vittorio Veneto. The Battle of Vittorio Veneto was fought from 24 October to 3 November 1918 near Vittorio Veneto on the Italian Front during World War I. The Italian victory marked the end of the war on the Italian Front, secured the dissolution of the Austro-Hungarian Empire and contributed to the end of the First World War less than two weeks later.
- The Armistice of 11 November 1918 was between the Allies and Germany – also known as the Armistice of Compiègne after the location in which it was signed – and the agreement that ended the fighting on the Western Front. It went into effect at 11 a.m. Paris time (10:00 a.m. GMT) on 11 November 1918 ("the eleventh hour of the eleventh day of the eleventh month"), and marked a victory for the Allies and a complete defeat for Germany, although not formally a surrender.