[SPOILERS for those not caught up on Doctor Who ahead.]
The latest promo for Doctor Who season 10 teases what's to come (and who's returning) over the episodes ahead. Doctor Who returned after an extended break last weekend with 'The Pilot', an episode primarily designed to introduce new companion Bill Potts (Pearl Mackie). The premiere also established Peter Capaldi's Twelfth Doctor as currently in hiding at an Earth university and tasked with protecting a vault of which the contents are unknown. Of course, by the end of the episode, The Doctor has succumbed to his adventurous tendencies and taken off with Bill in the TARDIS, presumably leaving Nardole (Matt Lucas) to babysit the mysterious vault.
It was previously announced that this season will see The Doctor come face to face with not one, but two versions of his infamous Time Lord nemesis The Master. Capaldi previously squared off against Michelle Gomez' Missy in his debut season and the character re-emerged to team up with Clara in Doctor Who season 9. As such, the announcement that Gomez would appear in season 10 didn't come as too much of a surprise; however, the fact that John Simm's David Tennant-era Master was also confirmed as returning was far more of a shock.
In the 'Coming Soon' trailer that rolled after the credits of 'The Pilot', many of season 10's forthcoming treats were teased; including the original-design Cybermen, the Ice Warriors and the Twelfth Doctor in the midst of a regeneration. The clip also teases the appearance of both incarnations of The Master, with Michelle Gomez seemingly set to appear in a medieval-themed episode, and the trailer concludes by lingering on a shot of John Simm's menacing visage - complete with a classic Master goatee.
Predictably, the trailer doesn't give away very much about the role the Masters will play in the episodes to come - and though they may eventually join forces, the promo refrains from showing Gomez and Simm together. As for the brief regeneration shot, Capaldi is confirmed to be leaving Doctor Who but also rumored to be appearing in the Christmas special; meaning that the shot in this trailer could be a false alarm, in the same vein as the Tenth Doctor's 'No worries, I'll just shove all this regeneration energy into my severed hand' moment. If the regeneration shot is the real deal however, it would be highly fitting for the Twelfth Doctor to meet his demise at the hands of two incarnations of one of his greatest foes.
The return of John Simm has pleased many fans of the David Tennant era of Doctor Who. His version of The Master was notoriously psychotic and Simm's madcap performance won him a raft of critical praise. As such, bringing the character back seems like a smart move - and the potential team-up between him and Missy would certainly be a tantalizing meeting of two highly unstable, but hugely entertaining personalities.
On the other hand, some fans see the decision to bring back Simm as a cynical attempt to recapture viewers who haven't enjoyed Capaldi's run as The Doctor. Recent seasons have seen a drop in viewership compared to Tennant and Matt Smith's tenures on Doctor Who. While Capaldi has many, many fans, not everyone has enjoyed his interpretation of The Doctor, although this is more to do with the writing than the actor himself.
Doctor Who continues with 'Smile' on Saturday, April 22nd on BBC1 and BBC America.