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.

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.

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.