Which C.S. Lewis book was published in 1945 as the final volume of his Space Trilogy?

That Hideous Strength was published in 1945 as the final volume of C.S. Lewis’s Space Trilogy. It follows Out of the Silent Planet, published in 1938, and Perelandra, published in 1943.

Unlike the first two books, the novel is set primarily on Earth. Its plot involves the fictional National Institute of Coordinated Experiments, or NICE, and examines the dangers of technocratic power, dehumanization, and the misuse of science. Elwin Ransom remains an important figure in the wider story.

The novel combines science fiction with academic satire and Arthurian elements. Its title comes from a line in David Lindsay’s poem “A Vision of Judgment,” which Lewis quoted in the book’s epigraph.

That Hideous Strength is sometimes mistaken for a standalone dystopian novel because its setting differs sharply from the Mars and Venus books. It is nevertheless the trilogy’s concluding volume, linking the planetary conflicts of the earlier books to a crisis involving human society on Earth.