In 1930s England, a group of pretentious rich and famous gather together for a weekend of relaxation at a hunting resort. But when a murder occurs, each one of these interesting characters becomes a suspect.

The beloved Crawleys and their intrepid staff prepare for the most important moment of their lives. A royal visit from the King and Queen of England will unleash scandal, romance and intrigue that will leave the future of Downton hanging in the balance.

A cavalcade of English life from New Year's Eve 1899 until 1933 is seen through the eyes of well-to-do Londoners Jane and Robert Marryot. Amongst events touching their family are the Boer War, the death of Queen Victoria, the sinking of the Titanic, and the Great War.

Mary Rafferty comes from a poor family of steel mill workers in 19th Century Pittsburgh. Her family objects when she goes to work as a maid for the wealthy Scott family which controls the mill. Mary catches the attention of handsome scion Paul Scott, but their romance is complicated by Paul's engagement to someone else and a bitter strike among the mill workers.

On marrying the boss's daughter, Richard takes his father-in-law's advice to hire a live-in domestic. He soon finds good help is hard to come by. Run-ins follow with dipsomaniacs, bank robbers, a Welsh lass who takes one look at London and runs, and an Italian charmer who turns the place into a bawdy house. Then when Ingrid arrives from Sweden things actually start to get complicated.