The first episode of the four-part drama begins in 1912, when the sinking of the Titanic punctures the succession plans of Lord Grantham (Hugh Bonneville), the father of three daughters, and inspires his wife (Elizabeth McGovern) and mother (Maggie Smith) to push him to separate his title from his estate, which are legally entailed to pass only to a man. The search settles on a young solicitor (Dan Stevens) unaccustomed to tawny trappings.
Part 2 of 4. Mary entertains three suitors, including a Turkish diplomat. In other events, much to his dismay, the former life of Mr. Carson is revealed; Mr. Bates risks his health in order to keep his post of valet; and the maid Gwen's aspirations for a profession beyond service become known.
Part 3 of 4. The rivalry between Mary and Edith reaches a fever pitch. In other events, Thomas and O'Brien plot against Mr. Bates while Anna's fondness for him grows; and Lady Violet's long winning streak at the annual flower show is threatened.
Conclusion. A possible heir alternative to Matthew comes to the fore; Sybil's secret political life causes her harm; Anna investigates Mr. Bates' past while in London with Mrs. Patmore, who needs eye surgery; Mary meddles with Edith's romantic plans; and Thomas plans his exit strategy.