The story starts with the philologi

The story starts with the philologist Elwin Ransom, some years after his return from Mars at the end of Out of the Silent Planet, receiving a new mission from Oyarsa, the angelic ruler of Mars. After summoning Lewis, the first person narrator, to his country home, Ransom explains to Lewis that he (Ransom) is to travel to Perelandra (Venus), where he is to counter some kind of attack launched by Earth's Black Archon (Satan).

Ransom is transported in a casketlike vessel seemingly made of ice, which contains only himself. He gets Lewis to blindfold him so the sunlight will not blind him once he travels beyond the earth's atmosphere. He does not wear any clothes on the journey as Oyarsa tells him clothes are unnecessary on Venus. He returns to Earth about a year later and is met by Lewis and another friend: the remainder of the story is told from Ransom's point of view, with Lewis acting as interlocutor and occasional commentator.

Ransom arrives in Venus after a journey in which he is surrounded by bright colours; the box dissolves leaving Ransom on what appears to be an oceanic paradise. One day is about 23 Earth hours, in contrast to the (roughly) 24 and 25-hour days of Earth and Mars. The sky is golden but opaque. Hence the sun cannot be seen, daylight is somewhat dimmer than on Earth, and the night is pitch black with no stars visible.