Doctor Who season nine will be getting underway soon and, per usual, there are plenty of questions surrounding what lies ahead next for The Doctor. Maisie Williams' mystery character is one of the most intriguing elements that will factor into this impending season's narrative arc; meanwhile, off-screen, speculation continues as to whether the current Doctor actor Peter Capaldi and/or Jenna Coleman (who plays The Doctor's current companion, Clara Oswald) shall continue their time-travel escapades, after this season is done.
However, we can now confirm something about the upcoming Doctor Who season; namely, it will wrap up with a Christmas special directed by Douglas Mackinnon (who most recently helmed the Doctor Who season eight episodes "Listen", "Time Heist" and "Flatline") - one that brings fan-favorite Alex Kingston as River Song back into the fold, for (at least) one more run with The Doctor.
River Song, the daughter of The Doctor's former traveling companions Amelia Pond (Karen Gillan) and Rory Williams (Arthur Darvill), was last seen in the Doctor Who season seven episode "The Name of the Doctor", where she bid farewell to Matt Smith's Doctor by appearing as a psychic echo to him. It's not yet been revealed what the in-show explanation will be for how River meets up with Capaldi's Doctor, though Kingston has expressed her delight at being back as Dr. Song - with filming on the 2015 Doctor Who Christmas Special now underway - via the following statement (via the BBC):
“To be honest, I did not know whether River would ever return to the show, but here she is, back with the Doctor for the Christmas special. Steven Moffat is on glittering form, giving us an episode filled with humour and surprise guest castings. I met Peter for the first time at Monday’s read through, we had a laugh, and I am now excited and ready to start filming with him and the Doctor Who team. Christmas in September? Why not!”
Current Doctor Who head writer/showrunner Steven Moffat, who penned the 2015 Christmas special, didn't offer any hints about the wibbly-wobbly timey-wimey (apologies, that's an obligatory reference) mechanism that will reunite River and The Doctor once more, choosing to instead simply acknowledge the tricky nature of their relationship with his own official statement on the news:
“Another Christmas, another special for Doctor Who - and what could be more special than the return of Alex Kingston as Professor River Song? The last time the Doctor saw her she was a ghost. The first time he met her, she died. So how can he be seeing her again? As ever, with the most complicated relationship in the universe, it’s a matter of time...”
One of our theories about Williams' character for Doctor Who is that she could be a new regeneration of River Song, though Moffat has since confirmed that the Game of Thrones star is not going to be playing a returning character. Regardless, Doctor Who Christmas specials are part of the show's official canon and in the past certain ones have covered major plot developments on the series - such as the passing of the torch (the sonic screwdriver?) from Smith to Capaldi - while other ones have been comparatively less impactful, as was the case with the 2014 iteration, "Last Christmas".
What will the case be with the 2015 special then? The Doctor Who season nine trailers have teased the Doctor and Clara's encounters with enemies new and familiar (see: Michelle Gomez's return as Missy), though nothing that really suggests the season narrative through-line will somehow tie in closely with a fresh appearance from River Song, near the conclusion. In all likelihood, River's return probably won't be teased until the final regular episode of this ninth Doctor Who season (perhaps not even until the final scene).
Nevertheless, having Kingston back on the show should be welcome news to many a Who-vian, eager to see how River's dynamic with Capaldi's Doctor differs from hers with Smith's - or even the pair of episodes that she shared with David Tennant's Doctor when River debuted in the season four episodes, "Silence in the Library" and "Forest of the Dead" (also penned by Moffat, as it were).
Doctor Who season nine premieres on the BBC and BBC America on September 19th, 2015.