Which C.S. Lewis novel is the third volume of the Space Trilogy?

That Hideous Strength is the third volume of C.S. Lewis’s Space Trilogy.

The trilogy begins with Out of the Silent Planet, published in 1938, and continues with Perelandra, published in 1943. That Hideous Strength followed in 1945. Unlike the first two books, which focus heavily on voyages to other planets, the final novel is set mainly on Earth and presents a struggle involving the scientific organization N.I.C.E., the National Institute of Co-ordinated Experiments.

The story combines science fiction, social criticism, Arthurian material, and Christian themes. Its protagonist, Mark Studdock, becomes entangled with N.I.C.E., while Jane Studdock encounters a different community and its spiritual concerns. The title comes from a line by David Lindsay in A Voyage to Arcturus, quoted as an epigraph. The trilogy’s publication order is clear, although some editions use the collective title “The Space Trilogy” and may emphasize its theological rather than purely planetary elements.