It is April 1912, and news arrives of the sinking of the Titanic with the loss of Downton's heir James and his son Patrick.

Matthew and his mother Isobel arrive at Downton, but trouble lies ahead as doctor's widow Isobel immediately finds her views at odds with Violet's.

Mary is instantly attracted to handsome Turkish attache Kemal Pamuk, but their romance is cut brutally short and sends ripples of unease through the house.

Violet and Isobel are in conflict over a medical ailment affecting Molesley, and Carson fears that there is a thief at Downton.

Mary is introduced to a potential suitor, but she thinks that he is too old and stuffy - meanwhile, Mrs Patmore fears she may be going blind.

Sybil's interest in politics gets her in trouble, Matthew and Mary's relationship takes an unexpected turn, and Bates makes a shocking revelation.

The family is astonished when Lady Cora Crawley finds that she is pregnant, and the announcement leaves Mary wondering how to answer Matthew's proposal.