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.
An old acquaintance comes to Edith's aid, while Mr Carson and Mrs Hughes' big day brings an unexpected arrival.
Anna and Mary face a crisis and a figure from the past surprises those above and below stairs.
Violet embroils the Minister of Health in the hospital row, but his visit ends in catastrophe and blood. Mary's suspicions about Marigold are aroused.
Downton Abbey opens its doors to the public for charity, Barrow's actions are misconstrued, Mary and Henry's romance blossoms, and tensions between Cora and Violet reach a dramatic climax.
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.
