Callaghan (Shadow of Death)

Callaghan was part of the Fifth Galactic Surveyor Corps, a survey team of human pioneers exploring a ruined city on a planet orbiting a pulsar in 2724.

The Second Doctor stayed behind in the planet's base to open the door to the surface for so the group could escape the Quiet Ones, as the outside door could only be opened from the control room. The Doctor eventually left the base, and explained he had made contact the Quiet Ones, and agreed to a truce in which surveyor team could continue to safely learn about and communicate with the Quiet Ones, if they did it more quietly. While minutes had passed outside, for the Doctor it was a few years. (AUDIO: Shadow of Death)