The overall mood of the story is one of gloom and impending doom. The red room where Shireen and Theremon talk acts as a symbol of blood and horror and death. The final sun in the sky Beta with its bricky light, the maroon carpet and red curtains, and the red liquor bottle–all represent a gloomy, scary atmosphere and hint at a mood of death and danger.
The red room very soon becomes the dark room with the curtains drawn by Theremon. This episode allows the author to comment on what darkness does to humans. It makes them aimless, mad brutes. The darkness without is also a symbol of the darkness within and is the recurrent symbol which appears at multiple junctures in the story and represents the evil in human actions.