Prologue (webcast)

 was the first prequel to the ninth series of Doctor Who, which was released 11 September 2015 on the Doctor Who website and BBC iPlayer.

Plot
The Twelfth Doctor has returned to Karn and discusses the nature of friends and enemies with Ohila, the leader of the Sisterhood of Karn. The two discuss an invitation given to the Doctor by an unnamed individual, someone who the Doctor has known for a long time, but has been enemies with for almost all that time.

Ohila doesn't believe the Doctor when he says he will not visit "him", and continues to question his reasons. Eventually the Doctor says he will go "soon", and gives Ohila an object that he says she knows who to give it to. The Doctor comments that he should go meditate somewhere and then leaves the meeting spot.

Cast

 * The Doctor - Peter Capaldi
 * Ohila - Clare Higgins

Crew

 * Writer - Steven Moffat
 * Director - Hettie MacDonald
 * Producer - Peter Bennett
 * Executive Producer - Steven Moffat
 * Executive Producer - Brian Minchin

Story notes

 * This is the first prequel, mini-episode, or webcast to feature the Twelfth Doctor.
 * This is the first time Ohila has been seen from a present standpoint in the series rather than in the past.
 * The Doctor's line to Ohila, "Look after the universe for me, I've put a lot of work into it." is identical to a line used in the 1999 Red Nose Day Comic Relief Doctor Who parody The Curse of Fatal Death, a spoof also written by Steven Moffat. The line in question was spoken coincidentally by that universe's version of the Twelfth Doctor as he was apparently dying for good. He asked his companion Emma, and the Master, to do the same.

Ratings

 * The video for this received over a hundred thousand views on YouTube within a week.

Filming locations

 * The whole story was filmed in the Taff's Well quarry in Cardiff, Wales.

Production errors
To be added

Continuity

 * The Doctor's fourth incarnation first met the Sisterhood of Karn and helped them when their flame was running out and Morbius was on the planet. (TV: The Brain of Morbius) Meanwhile, he had met Ohila in his eighth incarnation after the Sisterhood temporarily revived him from a fatal gunship crash. Ohila then gave him the means to regenerate into his war incarnation. (TV: The Night of the Doctor)
 * The Doctor said he would "probably go meditate on a rock". (TV: The Doctor's Meditation) He was previously meditating on top of the TARDIS. (TV: Listen)
 * The Doctor tells Ohila, "Look after the universe. I've put a lot of work into it." When he had just regenerated into his eleventh incarnation, he made a similar statement to the Atraxi regarding Earth. When the Atraxi noted he was not native to that world, the Doctor replied, "No, but I've put a lot of work into it." (TV: The Eleventh Hour)
 * Ohila is aware that the Doctor lies. (TV: The Big Bang, Let's Kill Hitler, The Wedding of River Song)

DVD releases
to be added

Blu-ray releases
to be added