"The Tenth Planet" is probably the most notorious of all the missing Doctor Who stories. Three of the episodes - the first three - are still held
by the BBC Archives. Part 4 was never officially junked, and rumours abound of its existence. The fact remains, though, that the episode has been missing since
'Blue Peter' showed a brief clip from the episode in 1974; after over twenty years, the chances of ever recovering the last episode are slim.
Part 4 of the story is sought after for two reasons. Firstly, as the only missing episode of the story, its recovery would allow the BBC to release the
complete story on video. Secondly, it marks the final moments of William Hartnell's tenure as the Doctor, and features the series' first regeneration scene.
While we now take regenerations for granted, the audience of 1966 would have been shocked by the final moments of the story.
The first three episodes of the story do still exist, and are available on video in fan circles, but we will be transcribing all four episodes in due course.