Trailer for Doctor Who series finale features explosive revelations

The tantalising footage from Dark Water (to be followed by Death in Heaven) seems to show Clara turning against the Doctor, and even implies she is this series main villain Missy in disguise. With smoke enveloping her, Clara is seen taunting a confused Doctor with the key to his time machine. “Do I have your attention?” she says in a less than friendly tone. “You will never step inside your Tardis again.”

After that it’s one body blow after another. Intercut with footage of a Cyberman invasion of London and the mysterious Missy being mysterious is Clara emerging from some kind of cell and generally acting like a villain.

At one point, she seems to push the Doctor out of a plane.

“Clara, what are you doing?” says a harried Time Lord who is clearly not in control of the situation (earlier, UNIT is shown confiscating his Tardis via a grappling claw). Then, even more worried: “Clara. My Clara. I don’t think you will,” he says in response to an off-screen threat from his companion.

CUT TO: The Doctor falling through clouds, with no parachute or Tardis in sight.

Apparently she will.

At the most intriguing moment, Clara tells a looming Cyberman: “I’m not Clara Oswald. Clara Oswald has never existed!” Clara ‘Impossible Girl’ Oswald has already had a confused backstory, but could she really have been a sleeper agent all of this time?

Could Clara and Missy even be the same person? It’s a popular fan theory. Plus earlier in the episode it was heavily implied Missy sent the young Maebh Arden looking for the Doctor: he's the one who assumes that the dark haired ‘Miss’ she referred to was Clara. Was this a telling case of mistaken identity? In the trailer Missy is heard teasing: “You know who I am…”

We will have to wait until next week for some answers, but to quote Missy: “Now that was surprising. I love surprises.”