Mary finds it was Edith who let the ambassador know about Pamuk's death, Cora announces her pregnancy, and Thomas and O'Brien hatch new slanders against Bates as War clouds loom.

April 1917. With John still absent, Isobel's butler Molesley makes a play for Anna but is rejected. Robert gets a new valet, shell-shocked ex-soldier Henry Lang, whilst William goes off to war. Edith learns to drive a tractor extremely well, and nearly succumbs to a kiss from the married farmer Mr. Drake. Sybil and Thomas work in the cottage hospital, where the latter begins to learn some humanity. At Isobel's suggestion - and to Violet's dismay - Downton Abbey is turned into a convalescent ward to ease the hospital's bed shortage. Mary invites middle-aged newspaper tycoon, and prospective beau, Sir Richard Carlisle to a dinner party, also attended by the Crawleys and Lavinia. Suspicious of Carlisle, Violet invites her daughter and sister to the Earl, Lady Rosamund, who is intrigued by the fact that Carlisle and Lavinia already seem well-acquainted. Carson, despite being taken ill whilst serving dinner, is still perceptive enough to suggest to Mary that Matthew is really the man for her.

Downton is turned into a convalescent hospital for the war wounded and through circumstances Thomas is given authority in its operation as Anna and Bates are briefly reunited and Branson plots against a heroic general dining at Downton.

Christmas 1919. Downton Abbey is hosting a lavish Christmas party, yet despite being the season of goodwill, tensions are rife and Bates' arrest has cast a shadow over the festivities.

Change arrives in a big way for several key characters at Downton Abbey. A yearly cricket match with the village sees old scores settled and new plots are hatched.

Anthony Gillingham returns to Downton to propose to Mary, Edna tries to coerce Tom into marrying her, and Anna will not tell Bates what's bothering her.

Cora's playboy brother, Harold, is in trouble, so Robert must travel to America to help bail him out; a new farming venture at Downton sees Blake and Mary putting aside their differences.

Rosamund comes up with a plan to help Edith, but Violet sees right through it; Isobel is the object of someone's attention, while Mary asks Gillingham for a very big favor.

Summer of 1923. It's summer and as part of Rose's 'coming out' she is to be presented at Buckingham Palace. The Crawley family go to London to prepare Grantham House for this busy social program.

The Countess confesses her past with Prince Kuragin, Lord Merton proposes to Isobel, Rose's parents are divorcing, Lord Grantham becomes jealous of Simon, and Lady Mary tells Gillingham she won't marry him.

Tom ends his relationship with Sarah, Rose meets a young man of Russian descent, Rosamund's visit to Marigold has consequences, Mrs. Patmore asks advice for her inheritance, and Simon Bricker expresses his love for Cora.

Atticus brings his parents, Edith and her daughter are brought home by Cora, Tom decides to take his daughter to America, Baxter volunteers to testify for Bates, and Isis is dying.

Lady Mary's past catches up with her when an unwelcome visitor delivers an ultimatum, and news about the running of Downton Hospital puts Violet on the warpath.

What begins as a happy day out for the family and servants ends in panic and leaves Robert with a difficult decision to make.

Anna and Mary face a crisis and a figure from the past surprises those above and below stairs.

The family face a shocking turn of events at Brooklands racetrack while Molesley and Daisy are put to the test.

Romance blossoms but a betrayal of trust threatens the chance of lasting happiness. Thomas considers desperate measures.

Mary endeavors to build bridges with her sister while Edith's secret continues to pose a threat. As Henry settles into the role of husband and stepfather, finding his place at Downton proves more difficult.

Cora's playboy brother, Harold, is in trouble, so Robert must travel to America to help bail him out; a new farming venture at Downton sees Blake and Mary putting aside their differences.

Rosamund comes up with a plan to help Edith, but Violet sees right through it; Isobel is the object of someone's attention, while Mary asks Gillingham for a very big favor.

Atticus brings his parents, Edith and her daughter are brought home by Cora, Tom decides to take his daughter to America, Baxter volunteers to testify for Bates, and Isis is dying.

Romance blossoms but a betrayal of trust threatens the chance of lasting happiness. Thomas considers desperate measures.

The family face a shocking turn of events at Brooklands racetrack while Molesley and Daisy are put to the test.

Anna and Mary face a crisis and a figure from the past surprises those above and below stairs.

What begins as a happy day out for the family and servants ends in panic and leaves Robert with a difficult decision to make.

Lady Mary's past catches up with her when an unwelcome visitor delivers an ultimatum, and news about the running of Downton Hospital puts Violet on the warpath.

The Countess confesses her past with Prince Kuragin, Lord Merton proposes to Isobel, Rose's parents are divorcing, Lord Grantham becomes jealous of Simon, and Lady Mary tells Gillingham she won't marry him.