The planet Venus.
Lieutenant - Survivor of a rocket crash on Venus.
Unnamed man - Another survivor, who dies from a lightning storm.
Pickard - Another survivor, who dies from insanity.
Simmons - Another survivor, who dies from giving up hope.
General Mendt - A person found dead the same way as Pickard.
The lieutenant, whose rocket landed and seeks safety with his men in one of the Sun Domes set up around Venus.
The unending rain of Venus, which tears away at the sanity of the lieutenant and his men.
The lieutenant slowly loses all his men to the rain and Venusian nature.
Alone, the lieutenant finally reaches a working Sun Dome.
The main theme is the struggle for sanity in an insane situation. The rain is unending and doesn't allow the men a moment of peace or calm. A related theme is the power of unfettered nature: there are various signs of how the Venusian land threatens the Earthians, from the rain itself to the electrical storm, to the vegetation which quickly covers a corpse. However, nature when tamed is humanity's tool. In that sense, the sun represents life, which ties into a related sub-theme: the power of the human will to survive on faith. While the lieutenant is the only one to reach an intact Sun Dome, he does so because he has faith that one will present itself. The others had given up because of various weaknesses: one survivor panics and runs into the electrical storm, another succumbs to insanity, and a third simply gives up hope.
A lieutenant and three of his man are the survivors of an Earth rocket crashed on Venus. They are walking in the never-ending rain of the planet towards one of the Sun Domes set up by the colonists, but the rain is taking a toll on their sanity. The Sun Domes are reprieves from the unending rain and general dreariness of Venus, with creature comforts and a miniature sun. They inflate a boat to paddle across a river and after crossing it see something - it turns out not to be the Sun Dome, but their rocket, as the two dead crew members from the crash proves. They realize that an electrical storm must have thrown off their compass and they now have food for only two more days. The electrical storm then approaches, and they try to stay away from its lightning bolts. One man tries to run but is struck dead by the powerful lightning before it finally leaves the area. As the survivors look at this newest corpse, they see vegetation already begin to crawl over him.
The men continue on their travels until they reach the Single Sea, the body of water surrounding the lone continent of Venus. The lieutenant takes the men south, believing there are two Sun Domes in that direction; as of last month, one hundred twenty-six Sun Domes have been set up, which would have been more of it wasn't for political pressure back on Earth. Simmons is the first to see a Sun Dome and they race to it - only to discover that no one is inside. Pickard laughs, realizing it was the Venusians responsible for the damage, coming out of the sea and attacking the dome, as they do on occasion, taking the bodies of the dead Earthians into the sea. There is no edible food or miniature sun, and holes poked in the ceiling provided no relief from the rain. The Lieutenant tells the others they'll be at the next Sun Dome by four that afternoon, but Pickard is skeptical. They continue on their journey, but they stop when Pickard says he needs to sleep. The lieutenant cannot sleep and sees Pickard go into a panic: Pickard shoots at the sky and then goes catatonic, standing in the rain with his mouth wide open. The lieutenant tries to rouse him out of his stupor but Simmons tells him that Pickard has suffered the same fate as General Mendt; Simmons shoots Pickard, a mercy to both him and themselves.
Now just two men, they continue on their journey but Simmons finally gives up as well, telling the Lieutenant to go ahead. He is unable to hear the lieutenant any more but has his gun, waiting for the lieutenant to be out of sight before shooting himself. The lieutenant now continues by himself and finally reaches the Sun Dome. Inside are other Earthians who are surprised and start to move towards him; he runs to the miniature sun, taking off his clothes as he does so.