After the heartwarming wedding celebration of Mr. Carson (Jim Carter) and Mrs. Hughes (Phyllis Logan) in the previous episode of "Downton Abbey" season 6, expect to see more drama happening in the sprawling mansion of the Crawleys in episode 4, airing next Sunday.

In a preview posted by Metro UK, an old familiar face is seen on the doorstep of Downton Abbey.

The official synopsis for the episode reads: "As Tom (Allen Leech) and Sybbie (Fifi Heart) settle back into life at Downton, the family and servants are surprised with the return of another old friend in unexpected circumstances. A visit from Sergeant Willis (Howard Ward) leaves Baxter (Raquel Cassidy) with a dilemma, while Thomas struggles to fill Mr Carson's shoes. As a crisis takes Anna (Joanne Froggatt) and Mary (Michelle Dockery) to London, will Bates (Brendan Coyle) find out what Anna has been keeping from him? Daisy (Sophie McShera) has a bone to pick with Cora (Elizabeth McGovern) and Mary's eye is caught by an admirer."

The teaser shows former housemaid Gwen Dawson (Rose Leslie) arriving in the mansion, but it does not reveal why she has returned in the first place. But it seems like this will not be a happy reunion among the household staff, since Thomas (Rob James-Collier) appears to be offended when she fails to greet any of her former workmates.

Gwen left Downton after the first season to try her luck as a secretary. Then the staff received a letter from her in season 4 to tell them that she is already married.

Has she returned in the mansion to get back her old position as a housemaid? Or has she come back to buy Downton Abbey from her former employers?

The fourth episode of the sixth and final season of ITV's "Downton Abbey" will air in the UK on Sunday, Oct. 11.