If you're a fan of "Downton Abbey," Sundays will be marked by a difference. The period drama's Season 6 finale episode ended with happiness for some and broken relationships for others. And devoted followers of "Downton Abbey" will have to wait another month to watch the drama unfold between Lady Mary and her younger sister, Lady Edith. The British drama's Season 6 Christmas Special will air on 25 December, and according to the show-runners, some new and old characters will appear in the last and final episode.

According to details revealed by the producers, the "Downton Abbey" Christmas Special episode will include some heartening moments shared between those upstairs and downstairs. Lady Mary (Michelle Dockery) will try to make amends with her sister, Lady Edith (Laura Carmichael). Perhaps she will succeed in her attempts, because the Christmas Special episode will introduce to viewers Bertie Pelham's (Harry Hadden-Paton) mother.

Nevertheless, Edith's past will pose a problem, especially for the new Marquess' mother, who, as Bertie put it, is traditional and strict.

The final episode will also depict Lady Mary and her husband Henry Talbot's (Matthew Goode) life as a married couple. According to one article: "As Henry settles into the role of husband and stepfather, finding his place at Downton proves more difficult."

Furthermore, a very pregnant Lady Rose (Lily James) will appear alongside her husband Atticus Aldridge (Matt Barber). They will be accompanied by Rose's father, Shrimpie.

Spoiler TV reports that the Christmas Special episode was filmed at Alnwick Castle, Northumberland, which served as the location for Brancaster Castle, and at London's Ritz Hotel.

"Downton Abbey" Season 6 Christmas Special airs on Friday, 25 December on ITV. The show premiers in America on 3 January on PBS.