- Writers: Julian Fellowes
- Stars: Allen Leech , Brendan Coyle , Dan Stevens , David Robb , Elizabeth McGovern , Hugh Bonneville , Jim Carter , Joanne Froggatt , Kevin Doyle , Laura Carmichael , Lesley Nicol , Lily James , Maggie Smith , Michelle Dockery , Penelope Wilton , Phyllis Logan , Raquel Cassidy , Rob James-Collier , Siobhan Finneran , Sophie McShera
September 1912. Designated heir Matthew Crawley and his mother Isobel arrive and move into a house in the grounds of Downton Abbey but Matthew is uncomfortable with having servants and is not keen on an arranged marriage - something he has in common with Lady Mary. Robert's mother Violet looks down on them as they are not from her class - Matthew is a working solicitor and Isobel a trained nurse and doctor's widow, who nonetheless impresses when she helps at the local hospital and saves the life of one of Robert's tenants. Cora upbraids the two nastiest servants, O'Brien and Thomas, for sneering at the Crawleys but impresses upon Mary the financial need for the marriage. Carson is blackmailed by Grigg, a man with whom he once had a music-hall act, but Robert takes his part and sees Grigg off. Whilst Carson feels foolish for having a less-than-aristocratic past, he is supported by Bates and the two men become friends.