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 the Oyarsa (the angelic ruler) of Mars. Ransom summons narrator-Lewis 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).