Isobel and Cora lock horns over control of Downton’s medical role. Mrs. Bird starts a soup kitchen. And Matthew and William embark on a perilous patrol behind German lines.
In the climactic battle of the war, Matthew and William go over the top to an uncertain fate. Vera plays a cruel endgame with Bates and Anna.
As the war nears its end, Downton’s aristocrats and servants put their lives back together. Mary and Sir Richard go estate hunting.
The Spanish flu strikes Downton, disrupting one match, hastening another and transforming the fortunes of all. Mary, Sybil and Robert each confront a moment of truth.