Lily James will return to Downton Abbey this Christmas for the final ever episode to be shown on ITV.
The 26-year-old reprises the role of Lady Rose Aldridge in the popular period drama. She was lately seen as the lead in 2015 Disney film Cinderella.
Patricia Hodge, best known for her role in BBC One comedy Miranda, is set to join the cast as the mother of Bertie Pelham (Harry Hadden-Paton).
Matt Barber returns as Lady Rose's husband Atticus and Peter Egan is also back for the finale as Lady Rose's father, Hugh MacClare, Marquess of Flintshire.
ITV has released more plot details about the end of the multi award-winning series, created by acclaimed writer Julian Fellowes.
Lady Mary (Michelle Dockery) endeavours to build bridges with her sister Edith (Laura Carmichael), and Lord and Lady Grantham (Hugh Bonneville and Elizabeth McGovern) continue to be surprised by the daughter whose secret poses a threat.
Meanwhile, Henry Talbot (Matthew Goode) settles into the role of husband to Mary and stepfather to George, but finding his place at Downton proves more difficult.
Below stairs, Carson (Jim Carter) faces some personal challenges, which prove that even he is not invulnerable to change.
The last ever episode promises fans all the love and loss, happiness and heartbreak of Downton Abbey, and as the family and servants prepare to welcome 1926, they celebrate an unforgettable New Year's Eve together at the great house.
The series finale features regular cast members Dame Maggie Smith as The Dowager Countess, Penelope Wilton as Isobel Crawley, Allen Leech as Tom Branson and Samantha Bond as Lady Rosamund Painswick.
The much-loved actors playing the servants, including Phyllis Logan, Brendan Coyle, Joanne Froggatt, Lesley Nicol, Sophie McShera and Robert James-Collier, will also take their final bow.
Downton Abbey, the highest rating UK drama of the past decade with an average of nearly 11 million viewers, debuted on ITV in 2010 and has since become a global phenomenon.
It is now seen in more than 250 territories worldwide. The broadcast of the season finale on Christmas Day will mark the end of a true icon of British television history.