Out of the Silent Planet is the first novel of a science fiction trilogy written by C. S. Lewis. The protagonist, a British university professor named Elwin Ransom, is kidnapped by the novel's two antagonists and taken to the planet Mars. Here he escapes from his captors and briefly wanders alone before encountering the Martians. He ultimately finds three intelligent races living there --- a race of poets (the Hrossa), a race of rationalists (the Sorns) and a race of technologists (the Pfifltriggi), along with a mysterious class of nearly-invisible beings that do not seem to be restricted to any one planet (the Eldila). Ransom, an expert in philology (i.e., linguistics) is able to learn the Martian language. He learns that the races there refer to their planet as Malacandra, and that their civilization is far older than Earth's.

Lewis, an adult convert from atheism to Christianity, uses Out of the Silent Planet (along with the two successive novels in the trilogy, Perelandra and That Hideous Strength) to convey philosophical ideas with Biblical foundations: in this novel, the idea of an ancient world that never experienced a fall from grace, in contrast to the history of our own world. The races of Malacandra have lived in complete peace for millions of years in their own Garden of Eden and find Ransom's descriptions of life on Earth difficult to comprehend. Lewis' description of the planet Mars is perhaps not terribly accurate from a purely factual standpoint --- it was, after all, written in the 1940's by someone whose education, though extensive, was not in the sciences --- but is an enchanting and poetic vision of what an innocent, unspoiled world might be like; and as a master of the English language, Lewis' writing is unique for its elegance, beauty and simplicity.

Ransom, the main character of the first two novels (he is a secondary character in That Hideous Strength), appears very similar to Lewis himself: university professor, expert in languages and medieval literature, unmarried (Lewis did not marry until his fifties), wounded in World War I and with no living relatives except for one sibling. Lewis, however, apparently intended for Ransom to be patterned after his friend and fellow Oxford professor J.R.R. Tolkien.