Cora's pregnancy throws the inheritance issue into doubt. Matthew must wait for an answer to his wedding proposal. O'Brien discovers more compromising information about Bates. Thomas leaves.

Sybil puts herself in danger when a fight breaks out. Sybil's sisters notice Matthew's feelings for her. Mary is surprised by a marriage proposal. Bates clears his name over the missing wine but resigns rather than name the real culprit.

Cora's tries to set up Mary with Evelyn Napier, who falls for his friend instead, with significant consequences for the household. Bates takes action to help cure his limp.

Isobel finds herself at odds with Violet. Mary is introduced to a potential suitor but wants to be with Matthew. Anna works out who stole a valuable snuff box. O'Brien plans a way for Edith to get even with Mary.

After the death of the heir, Violet wishes that Robert's daughter Mary could inherit Downton Abbey.

Matthew Crawley and his mother Isobel arrive at Downton, and have difficulty settling in. Carson is mortified when confronted by his past. Violet attempts to promote a match between Matthew and Mary. Isobel is elected to serve on the hospital board.

Cora’s mother sweeps into Downton for Matthew and Mary’s wedding, but with the couple’s relationship under strain will they even make it to the altar? New footman Alfred strives to meet Carson’s high standards, under the watchful eye of his aunt O’Brien. Robert’s shocking news brings financial worries to the fore, on an unprecedented scale. Might he lose Downton itself and all it stands for?

Mrs Hughes finds herself the focus of speculation when she meets a former suitor who makes her question her position. Violet and Isobel clash over a medical ailment affecting Molesley. Carson is concerned there is a thief at work in the grounds.

Bertie's circumstances change suddenly, leaving Edith uncertain whether to risk telling him the truth or keep her past a secret at all costs. Mary wonders if she can ever make peace with her sister as hostilities escalate, Spratt shows some hidden talents and Molesley's first day as a teacher does not go according to plan. Mrs Patmore's bed and breakfast attracts unwanted attention, leaving her in need of the Crawleys' help.

Tempers are left on edge after a kind gesture by Isobel backfires. Mary attempts to fight Branson's corner after his decisions are put under scrutiny. Robert and Cora's relationship feels the strain and Violet attempts to make them see things differently. Some extreme measures are taken by Bates.

Mary starts to get over the grief she is feeling, and takes an interest in the running of the estate. Lady Rose MacClare, Lady Flintshire's daughter, ends up in a predicament at a tea dance in York. Hughes attempts to convince Carson to heal an old wound.

Carlisle threatens to ruin Mary if she jilts him. A major comes to stay - but is he really who he claims to be? Bates learns that Vera has succeeded in scuppering the divorce.

How long can Sybil and Branson keep their secret? Carlisle puts Anna in a difficult position, Bates is left reeling from the news about Vera, and Thomas embarks on a new scheme.

The Crawleys watch Henry compete in a motor racing event, an occasion that leaves Mary reeling. Violet hatches a plan which surprises the family and delights Miss Denker, and learns more about Amelia's intentions in befriending Isobel. Molesley and Daisy rise to the challenges of examination day, Andy's secret is brought to light, Thomas feels isolated, and Mrs Patmore and Mrs Hughes teach Carson a lesson.

With the wedding approaching there is excitement in the air, but will Branson's plans rattle everyone? A decisive Anna forces Bates to think about their future.

The estate's future is hanging in the balance and Mary is hoping to receive a bailout from grandmother Martha. Violet also attempts to help her make sure that Downton puts on a bigger show than ever before with a grand party for friends and neighbours. Mrs Hughes gets some news that worries her. O'Brien's attempts to boost Alfred's progress are met with disapproval from Thomas.

An extravagant house party at the Abbey gives the Crawleys a chance to reconnect with old friends. But some guests prove more welcome than others, and along with the celebrations come skulduggery and heartache.

The Great War unsettles life at Downton and surprising news about Matthew rocks the family. New maid Ethel irritates O'Brien - and Bates returns with devastating news for Anna.

Robert receives some shocking news from the front. Daisy's relationship with William moves faster than she would like. Vera threatens to expose old secrets.

A birthday party is planned for Robert, but Rose's surprise contribution to the event ruffles feathers above and below stairs. A new farming venture on the Downton estate comes with dramatic repercussions for Mary, and Edith receives more unwelcome news.

Cora's playboy brother has got himself into a spot of bother and Robert has to make a trip to America to bail him out. Blake and Mary are forced to put aside their differences to deal with a new farming venture on the estate. When Violet is taken ill, help comes from an unlikely quarter. In spite of Mrs Hughes, Mrs Patmore and Carson's attempts to keep the peace, romantic tensions below stairs cause problems.

Neville Chamberlain visits Downton for dinner, and is drawn into Violet’s plan to save the hospital, with distressing consequences for everyone. Andy finds an unexpected confidante while helping Mr Mason move into Yew Tree Farm, Mary is uncertain if she has met her match, Edith meets Bertie Pelham in London, and Spratt comes to Denker’s aid. Mrs Hughes struggles to keep Carson happy, while Mary thinks secrets are being kept from her.

The house is made open to the public to raise money for the hospital, an act that divides opinions among the family and the servants. Tensions between Violet and Cora come to a head as a decision is made about the hospital takeover, Mr Dawes has a proposition for Molesley, and Baxter is thrown into turmoil by an unexpected letter. Carson is not happy with Thomas, while Mary and Edith hope to overcome their past and find new happiness with the men in their lives.

New mother Mary is finding it hard to come to terms with Matthew's shocking death. Robert and Violet fall out over how to handle the situation. Jimmy takes an interest in Ivy, while Carson receives an unwelcome reminder from his past.

As Tom and Sybbie settle back into life at Downton, the family and servants are surprised by the return of another old friend in unexpected circumstances.