Mary is still inconsolable six months after Matthew's death, Edith supports Michael going to Germany to divorce his wife, Molesley looks for a job, and there is a surprise applicant for Ms. O'Brien's job.

An unofficial will from Matthew comes into the family's hand, Thomas plots against Anna, Rose gets involved in a scrap at a servant's dance, and Mrs. Crawley tries to reconcile Carson and Trigg.

A birthday party is planned for Robert, but Rose's contribution to the event surprises those above and below stairs, a new farming venture on the Downton estate comes with dramatic repercussions for Mary, and Edith receives troubling news.

Tim Drewe guesses the parentage of Marigold, Mary receives another proposal from Tony, Violet plays matchmaker, Thomas continues to press Baxter for information with blackmail, and a flash fire threatens the mansion.

Mary wakes up in bed with Tony Gillingham after their tryst and returns to Downton, where she learns that a building firm want to buy land for a housing estate, to which Robert objects. Violet discovers from her butler Spratt about Mary and Tony but covers for her before summoning her for an explanation. Mary explains to her that she plans to marry Tony but later tells Tom the truth, that she has no intention. In return he confesses that he is considering a move to America. Following the policeman's visit, Anna is perturbed that her ordeal will be revealed, particularly as the animosity between John and Green comes to light. John gives his alibi, that he spent the day in question in York, and Mrs Hughes and Mary agree to collude with this. As Barrow goes to visit his dying father, Baxter tells Cora that she was beguiled into the jewel theft by a cruel footman called Peter Coyle, whom she loved but who fled leaving her to take the blame. Tim's wife wants to bar Edith from seeing Marigold, whilst Rose hosts a benefit for a group of Russian political exiles and Violet is taken aback by one of their number.

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.

Violet's new maid doesn't seem to be working out, Kuragin reveals he still loves Violet, Anna realizes Bates' innocence, and Thomas reveals a secret to Baxter.

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.

Kuragin tells Violet he wants to live with her, someone tries to break up the Atticus Rose wedding, Daisy wants to live in London, and Anna is accused of Green's murder.

Autumn of 1924. It's grouse shooting season and Rose's father-in-law invites the Crawley family to a shooting party in Northumberland.

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.

An old acquaintance comes to Edith's aid, while Mr Carson and Mrs Hughes' big day brings an unexpected arrival.

Violet embroils the Minister of Health in the hospital row, but his visit ends in catastrophe. Mary's suspicions are aroused.

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.