The Spare-Part People

The Spare-Part People, also known as The Brain Drain and The Labyrinth, was an unproduced script written by Jon Pertwee and Reed De Rouen for Season 8. It was submitted in the summer of 1970, but was rejected after the production team decided they wanted the Master to feature in every story that season. Pertwee tried to rework the script, but Rouen was attached to the original version and stepped down from the project altogether. Pertwee later stepped down as well.

The first version saw the Doctor investigating a series of disappearances at Cambridge University. The second version saw the Doctor and UNIT hunting for the Master, now stranded on Earth. In both versions, the Doctor was led to Antarctica, where he found an alien ship buried beneath the ice. This ship was host to a crew of aliens that had been kidnapping humans and using their organs to sustain themselves.

Both versions had a similar resolution, involving an artificial bacteria that the Doctor used to make the aliens allergic to human DNA. In the first version however, this resulted in the death of the alien crew. Pertwee thought this was out of character, and rewrote the ending so that the crew survived and left Earth.

In Pertwee's incomplete version, it was suggested that these aliens were the ones who called the Master to Earth to begin with, as a distraction for the Doctor. This version may also have hinted at some familial connection between the Doctor and the Master.