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 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.

Tensions flare between Isobel and Cora. Ethel's flirtation with Major Bryant lands her in hot water. There is worrying news about Matthew. Branson declares his feelings for Sybil.

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.