: The society is controlled by "The Seers," who value radioactive energy over human life.
: The Doctor discovers troglodytes working in a nebula's core full of caves, overseen by men who use "fumigation" as a means of control. [S15E18] Underworld 2
: Critics generally find Part Two to be the weakest segment, describing it as "extremely dull" with roughly 20 minutes of "walking around and gas". : The society is controlled by "The Seers,"
: This serial is notorious for its heavy use of Color Space Overlay (CSO) , a primitive green-screen technique, to create the cave settings. Reviewers from IMDb note that while the lasers and some CSO effects work, others look "simply awful". a primitive green-screen technique