What is the title of C.S. Lewis’s science-fiction trilogy set partly on Mars?

C.S. Lewis’s science-fiction trilogy set partly on Mars is The Space Trilogy.

The trilogy consists of Out of the Silent Planet, Perelandra, and That Hideous Strength. The first novel, published in 1938, follows Cambridge philologist Elwin Ransom after he is taken to Malacandra, the planet humans call Mars. The second book takes Ransom to Perelandra, or Venus, while the third shifts much of its action back to Earth.

Lewis combines planetary adventure with theological, philosophical, and moral questions. The books reflect his interest in medieval cosmology and his concern about scientific power separated from ethical responsibility. Ransom is not a conventional space-opera hero; his academic background is central to the plot and to the trilogy’s language-focused worldbuilding.

The series is sometimes called the Ransom Trilogy, after its protagonist. That alternate name does not describe a separate work. The Mars setting belongs specifically to Out of the Silent Planet, while the complete three-book sequence ranges across multiple worlds.