Downton Abbey special: All you need to know

Lady Mary (Michelle Dockery) visits her maid Anna (Joanne Froggatt) in prison.

A month after it screened in Britain, Downton Abbey fans are getting to see the period drama's annual Christmas Special, which Prime has split into two halves (tonight and next week) for local consumption. Here's a guide to the new episodes.

When and where is it set?
We rejoin the family in autumn 1924. Lady Rose's father-in-law Lord Sinderby (James Faulkner) has rented Brancaster Castle in Northumberland - with spectacular Alnwick Castle (Harry Potter fans will recognise it as Hogwarts, where Maggie Smith used to work) standing in for the fictional estate - and invited the Crawleys to a grouse-shooting party. If that's not festive enough we get back to Downton itself just in time for Christmas.

So any new cast members?
While tweed is donned and good sport is enjoyed, guest star Alun Armstrong steps in to play the Sinderby's butler, Stowell, with scowling relish. He has an axe to grind and is in possession of a scandalous secret that threatens to ruin the party. The Russians are also coming, in the shape of the mysterious Princess Irina (the formidable Jane Lapotaire), estranged wife of Prince Kuragin (Rade Serbedzija). What will the Dowager Countess make of it? Matthew Goode (The Good Wife, The Imitation Game) appears in the Christmas episode as (yet another) love interest for Lady Mary.

Isn't George Clooney meant to be in it?
No, that was a festive comedy sketch for charity in Britain.

What about the more familiar faces?
The servants hold the fort back at Downton. As Anna (Joanne Froggatt) faces imprisonment for Mr Green's murder and is visited by Lady Mary, Bates (Brendan Coyle) takes drastic measures to clear her name. Baxter (Raquel Cassidy) and Molesley (Kevin Doyle) are busy on a joint plan and Carson (Jim Carter) and Mrs Hughes (Phyllis Logan) consider a business venture.

So no shock deaths?
No. Elizabeth McGovern, who plays Lady Cora, has said, "I can say that there aren't any sudden deaths."

So it's all very nice and Christmassy then?
Hugh Bonneville, who plays Lord Grantham, said of the special, "It is very heartwarming. You will have a lump in your throat." And there is a very big Christmas tree, surrounded by happy children.

When and where: Prime TV, tonight, 8.30pm, and next Thursday, 8.30pm.