The highest of the highs was the birth of Mary's and Matthew's son, the male heir for the Crawley family. Also the aristocrats and servants enjoyed a splendid ball in Scotland together at Shrimpy's manor. Anna learned a Scottish dance to please her husband Mr. Bates, who she found out had Scottish blood. Unlike Shrimpy's marriage, the Earl's is in fine shape. Cora is even allowing Wild Rose, Shrimpy's daughter, to come to live at Downton Abbey.
Then on the way home from seeing his son Matthew has a car crash. He is dead. As yet, the family, including Mary, does not know.
Another emotional tough spot has been Branson's ordeal with a servant girl who didn't know her place. She made Branson feel ashamed at his new position in life. It took the wisdom of Mrs. Hughes for him to see what had gone on and to get on the other side of it. Meanwhile he broke down in tears because he missed Sybil so much.
Although Edith is not at all sad that she will be the mistress of a married man - her editor - the rest of the family will be made to suffer. After all it is circa 1920 and the elite isn't ready for this kind of scandal. The editor can't divorce his wife because she is in a nut house, forever.
Another bit of darkness is that Shrimpy has lost his money. He will have to give up his fine estate. That means he not only is in a loveless marriage but also has to accept another kind of lifestyle.
The fourth season of "Downton Abbey" will start with the solid bonds among the family members and with their loyal servants. In the background will the pall of the second major tragedy to visit the family. Will Mary, who has a mean side, turn into shrew or will suffering soften her? How can the Earl live with the scandal of a daughter who took up with a married man from the working class? And can Branson manage the business of Downton on his own?