The Doctor Who Christmas Specials are part of British telly tradition, but interest in this year's festive instalment ('Twice Upon a Time') is more feverish than ever.
Why? Because it marks a turning point for the 54-year-old sci-fi series - and a historic first.
A changing of the guard, not just for the Time Lord himself (soon to be 'herself'), but also for showrunner Steven Moffat, who is stepping down after seven years to pass the baton on to new writer Chris Chibnall.
Plot details of the 2017 Doctor Who Christmas Special are still scarce, but here's what the BBC has drip-fed to eager Whovians so far.
It's goodbye from Peter Capaldi
After four years in the iconic role, the Scottish actor will bow out this Christmas.
He's become a much-loved Doctor among fans, and has easily overcome those early accusations that he was too old for the role.
In the finale to series 10, Capaldi was mid-regeneration already, having been blasted by marauding Cybermen and only just making it back to the TARDIS.
It remains to be seen what Moffat has planned for his swansong.
Mark Gatiss has a major role to play
In a preview clip released for Children in Need (see above), we find Mark Gatiss in the TARDIS, alongside Capaldi and David Bradley as 'The First Doctor'.
The Sherlock and League of Gentlemen actor is playing a character billed only as 'The Captain' - and it remains to be seen whether this is related to popular classic series companion the Brigadier.
In the preview, Capaldi and Gatiss have an amusing exchange that reveals more about The Captain's origin:
Gatiss: "Am I going mad?"
Capaldi: "Well you're an officer from World War One, at the South Pole being pursued by an alien through frozen time. Madness was never this good."
Gatiss: "World War One?"
Capaldi: "Judging by the uniform, yes."
Gatiss: "What do you mean, 'one'?"
Capaldi: "Oh sorry, spoilers."
One other fan theory is that Gatiss could be playing the real-life historical figure Gilbert Mackenzie Trench - the man who invented the police box and actually fought in WWI.
David Bradley plays 'The First Doctor'
Veteran actor Bradley (Harry Potter, Game of Thrones) will be reprising his role as the First Doctor from 2013’s ‘An Adventure in Space and Time’ docudrama, and his resemblance to William Hartnell, who was 55 by the time he was cast as The Doctor, is uncanny.
The same clip also offers a similarly witty exchange between Bradley and Capaldi.
Bradley: "Do I become... you?"
Capaldi: "Well there's a few false starts but you get there in the end."
Bradley: "Do I get... younger?"
Capaldi: "I am younger!"
There will be more familiar faces
Pearl Mackie will reprise her role as The Doctor's companion Bill Potts. However, this will be the last that Who fans will see of her in the show, as Chibnall prepares to put his stamp on the show with new companions (more on that below).
It’s also been rumoured that Jenna Coleman will make a brief appearance as Clara Oswald, but that remains a rumour for now.
And there's the small matter of a new Doctor
Of course, the biggest Who news this year has been the casting of Jodie Whittaker as the Thirteenth Doctor.
Going by tradition, the Broadchurch star will likely play just a small post-regeneration part in the final moments of the hour-long Christmas special, allowing Capaldi to enjoy his last hurrah in full.
Whittaker will really be able to sink her teeth into the role next year, when Chibnall gets his new era under way in series 11, when she'll be joined by Bradley Walsh, Tosin Cole and Mandip Gill as the newest companions.
One of the few official announcements we've had since the news of her casting back in July was the first image of her outfit, which features braces, a long coat, cut-off trousers and a colourful t-shirt.
Why will it be worth watching?
We can be sure that Moffat will want to go out with a bang.
The head writer has divided fans over the past seven years, but he's likely to be in his comfort zone here, with Bradley's appearance signalling yet more reverence for Doctor Who mythology.
What's more, 'Twice Upon a Time' will be directed by the experienced Rachel Talalay, who helmed the final two episodes of series 10.
And of course there will be huge interest in Whittaker's historic debut as the first ever female Time Lord.
Who will be the villain?
There's little to go on here, but there is a clue to be found in the preview clip, when The Doctor refers to The Captain being "pursued by an alien through frozen time".
That would appear to rule out the Cybermen, as they're not normally described as "alien" (even if they are from the Planet Mondas).
It could be a baddie from previous scrapes, such as the Vykoids, a troll-like alien race who featured in 'The Forgotten Army Doctor Who' novel.
Alternatively, Moffat may bring back some of his own antagonists, such as The Silence or The Weeping Angels - or he may have conceived a new foe altogether.
When will it be broadcast?
'Twice Upon a Time' will be broadcast on Christmas Day on BBC One.
The exact time is still to be confirmed, but in previous years Doctor Who has been broadcast in the early evening, between 5pm and 7pm.
We should find out more details in early December.
Originally published on our sister title, iNews.