Two time 'n' space defying stars of the season face off in this year's "Doctor Who" holiday special, "Last Christmas," which airs on Thursday on BBC America.
The courtship of reality and illusion is showcased in this latest battle to save the universe, as are issues of courage, death and the one-night present-delivery system. But it's the wary dance between two holiday icons that steals the show.
The Doctor (currently played by Peter Capaldi) has fought plenty of fake Santas, but he's never come up against the man himself. Neither have we, for that matter, or at least not Santa as envisioned by Steven Moffat and played with action-hero hilarity by Nick Frost.
This Santa may have all the trappings of traditional myth — the elves, the reindeer, etc. — but his knowledge extends well beyond naughty and nice, and he's clearly been keeping an eye on the Doctor.
For very good reason too. Aside from Santa, no other character in literature has as intense and changeable a relationship with Christmas as the Doctor.
In the years since it was rebooted by Russell T. Davies in 2005, the BBC series has always included a Christmas special. In keeping with general tradition, the episode is narratively lush, gorgeously cinematic and garlanded by A-list guest stars of such cultural diversity as über-thespian Michael Gambon ("A Christmas Carol") and pop singer Kylie Minogue ("Voyage of the Damned").
More important, the episode can reveal big changes for the next season, which have included the introduction of new companions and the identity of the Doctor's latest regeneration.
In other words, the Doctor, a character burdened by the sins of time and space on a self-appointed quest to save humanity, is regularly reborn on the day that traditionally marks the birth of Jesus.
Make of this what you will.
The 12th Doctor, Capaldi was only just introduced last Christmas as the replacement for No. 11, Matt Smith, so everyone can relax on that front; Capaldi's not going anywhere. Current companion Clara (Jenna Coleman), on the other hand, is the focus of much speculation.
She came to Matt Smith's Doctor in the 2012 Christmas special, "The Snowman," and although companions can serve as a bridge between one doctor and the next, none has appeared as a regular costar for more than a season after that.
Make of this what you will as well; there will be no breaking of the overzealous spoiler prohibition plea that accompanied the critics' preview of "Last Christmas."
Suffice to say that although the "Doctor Who" specials often skew toward Christmas past — Victorian, Edwardian, Narnian — this one stays current and strikingly modern. Reunited some time after this year's season finale appeared to tear them asunder, the Doctor and Clara come to the aid of a group of scientists beset by monsters more sci-fi than seasonal.
The action is a truly creepy and occasionally festive, a signature mash-up of humor, unease and deep thought. In honor of the day, the episode mostly occurs at the South Pole, which explains Santa, whose biggest gift to the world this year may turn out to be a fully realized 12th Doctor.
Over this past season, Capaldi and the show's writers struggled to find the newest iteration's personality and place in the Whovian universe. But as one impossible man of Christmas spars with the other, the Doctor loses the awkward brittleness that has plagued him and softens, just enough, to let Clara, and us, love him once more.
Should Clara leave the Doctor's side, for whatever reason, though I'm certainly not saying that's what happens, Frost's Santa would be a terrific replacement.
Imagine it: The Doctor and Santa taking on the great battles of the universe, maybe even finding the lost planet of Gallifrey.
Every day would be Christmas, indeed.
Where: BBC America
When: 9 p.m. Thursday
Rating: TV-PG (may be unsuitable for young children)