The books in the trilogy are:
- Out of the Silent Planet (1938), set mostly on Mars (Malacandra). In this book, Elwin Ransom voyages to Mars and discovers that Earth is exiled from the rest of the Solar System. Far back in Earth's past, it fell to an angelic being known as the Bent Oyarsa, and now, to prevent contamination of the rest of the Solar System ("The Field of Arbol"), it is known as "the silent planet" (Thulcandra).
- Perelandra (1943), set mostly on Venus. Also known as Voyage to Venus. Here Dr. Ransom journeys to an unspoiled Venus in which the first humanoids have just emerged.
- That Hideous Strength (1945), set on Earth. A scientific think tank called the N.I.C.E. (The National Institute of Co-ordinated Experiments) is secretly in touch with demonic entities who plan to ravage and lay waste to planet Earth.
- The Dark Tower and Other Stories (1977), set on Earth. This anthology of futuristic fiction reveals another side of Lewis's creative work on reality and spirituality, from a science fiction story about Cambridge intellectuals witnessing the breach of space-time to a short story about a blind man chasing the idea of light.
Connection to Tolkien
After the release of The Hobbit, C.S. Lewis wanted to try to produce a best-selling book like J.R.R. Tolkien, his close friend. In a meeting between Lewis and Tolkien, they decided that Tolkien would write a time-travel story, and Lewis one on space travel. So Lewis wrote his space travel book, Out of the Silent Planet, which later becomes the first book in the Space Trilogy. Tolkien writes his book too, but never finishes it; it is published later by his son Christopher, as The Lost Road and Other Writings.
- "Out of the Silent Planet begins the Space Trilogy with the adventures of the remarkable Dr. Ransom, who is abducted by aliens and taken by spaceship to another planet. In the second book, Perelandra, Dr. Ransom must battle evil on a new world when it is invaded by the Devil's agent. The final book, That Hideous Strength, concludes the adventures with Dr. Ransom in a world of superior alien beings and scientific experiments run amok, as he struggles with questions of ethics and morality in his quest for truth."
- —From the publisher
- Lewis, C.S. Out of the Silent Planet. London : The Bodley Head, 1938.
- Lewis, C.S. Perelandra: A Novel. London : The Bodley Head, 1943.
- Lewis, C.S. That Hideous Strength: A Modern Fairy-Tale for Grown-ups. London : The Bodley Head, 1945.
- Lewis, C.S. The Dark Tower and Other Stories. Walter Hooper, ed. London: Collins, 1977.