The Prisoner of Time (unproduced TV story)

The Prisoner of Time was an unproduced script written by Barry Letts for Season 13. It was commissioned on 21 January 1975, but Philip Hinchcliffe felt the story didn't keep in line with the tone of the season.
The story would have revolved around a being capable of moving through time, imprisoned by the Time Lords on a moon that they had frozen in time. The Doctor is telepathically contacted by the prisoner whilst refuelling his TARDIS at a Time Lord station and sets out to rescue them.