Most of "The Well" takes place in a mining colony on Planet 6767. The facility's purpose is to extract diamonds from five miles beneath the surface, so a mineshaft was put in place.

In "Doctor Who" season 2 episode 3, aka "The Well", the Doctor's quest to return Belinda Chandra to Earth on May 24, 2025, takes a detour to a dead world hundreds of thousands of years in the future.

“Midnight” ends as an unsolved mystery, whereas “Doctor Who” episodes usually tie everything up in a bow at the 45-minute mark. The monster, we must presume, is still out there.

BBC. The Doctor soon learns that the entity, whatever it is, kills anyone who stands directly behind Aliss. He also soon discovers the planet, now just designated 6767, is made of diamonds and ...