In a Christmas tradition that to its fans has become as reliable as presents under the tree, science-fiction series “Doctor Who” is set to bridge its most recent ninth season and upcoming 10th with a Dec. 25 holiday special, enigmatically titled “The Return of Doctor Mysterio.”
And as that title might suggest, BBC America is keeping plot details mostly under wraps, to protect what is intended as a surprise gift for audiences. “It’s only an hour long,” says showrunner Steven Moffat, laughing. “If you started early enough, you could show all of it in commercials.”
To a degree, Moffat can afford to play things close to the vest.
“Doctor Who,” which centers on a humanoid alien (Peter Capaldi) whose adventures through time and space often involve human companions and alien enemies, is a full-blown cultural phenomenon. And thanks to its unparalleled lifespan — the show originally ran from 1963 to 1989, but a 2005 reboot has brought it immense viewership well outside the United Kingdom — the show’s rabid, international fan base also spans generations. When it comes to the Christmas specials, one-off episodes that often find the Doctor traveling without a companion, audiences have learned to permit the creative team a healthy modicum of mystery.
That said, Moffat is happy to play up one key detail: The special finds the Doctor joining forces with a costumed crime-fighter named Grant (Justin Chatwin). Unlikely allies with differing ideologies, they team up to take on an extraterrestrial threat in modern-day New York.
Such a setup is new for “Doctor Who,” which is more concerned with space invaders than superheroes. But to Moffat, the concept held personal resonance.
“I’ve always been fascinated by the idea of maintaining a secret identity,” he says. “I was an incredibly mild-mannered, meek, underimpressive, underwhelming little boy, and I thought it’d be marvelous if people didn’t realize that secretly, at night, I turned into a god and kept them all safe. That’s a very attractive idea, to all the real-life Clark Kents that they might actually be Supermen when everybody glances away.”
According to executive producer Brian Minchin, Moffat’s passion for the idea made all the difference. The showrunner had previously pitched bringing a superhero into a different episode, and though that concept fell through, Minchin remained intrigued by Moffat’s idea of the interplay between the Doctor, who shrugs off the mantle of heroism, and a superhero who would embrace it.
“Steven as a writer has always been fascinated by this world, and he’s never written about it before,” says Minchin. “To get someone of his caliber to take on the superhero genre was really interesting to me.”
Though superhero cinema has been saturated with doom and gloom in recent years, the episode takes most of its cues from the upbeat Christopher Reeve “Superman” films, and their exploration of identity.
“I was very moved by those films, where Clark Kent isn’t the only dork,” Moffat says. “Superman is also a dork, but he’s just a different kind — two classically innocent, rather lovely versions of a simpler age of heroism. In the special, [Grant is] trying to reconcile the impossible, irreconcilable two halves of his life.”
Also in the mix are an evil corporation, an investigative journalist played by Charity Wakefield, and the bumbling, outsized Nardole (Matt Lucas), a breakout character in last year’s special who rejoins the Doctor this time around. Both Moffat and Minchin were mum on further details, but they promise a cheery, intrepid tone that marks a step toward the light after the show’s darker, though acclaimed ninth season.
“We had to pull it out of that nosedive
. . . so that ‘Doctor Who’ could get back to being fun,” says Moffat. “The Doctor loves what he does, and he loves whipping around the universe — he has a great time out there. And it’s important that’s the default setting of ‘Doctor Who,’ as opposed to the tremendously dark journey he can be on at times. You want both, and you’ll certainly get both next season, but the fundamental version of ‘Doctor Who’ has a lot of joy and humor in it.”
Minchin calls the special “a crowd-pleaser-type episode,” and Moffat agrees.
“It’s not a particularly Christmas-y episode,” he warns, laughing. “In fact, Christmas is mentioned exactly once and only in passing — but it’s Christmas-y in the sense that it’s the kind of family blockbuster you’d want to watch on Christmas Day, with lots of action, scares, and excitement.”
THE DR. WHO CHRISTMAS SPECIAL
Starring: Peter Capaldi, Justin Chatwin
On: BBC America, Dec. 25
Isaac Feldberg can be reached by email at isaac.feldberg@globe.com, or on Twitter at @i_feldberg.