For the World is Hollow and I Have Touched the Sky
Series: Star Trek
Airdate: November 8, 1968 | Year Set: 2268
Season 3, Episode 8
Summary
After Dr. McCoy informs Captain Kirk that he is dying, the Enterprise crew discovers a planetoid that is on a collision course with a inhabited world. Kirk, Spock and McCoy beam down and discover it is a populated space ship where most of the inhabitants having no clue they are on a space ship.