Which C.S. Lewis novel completes the Space Trilogy and is set largely on Earth?

That Hideous Strength completes C.S. Lewis’s Space Trilogy and is set largely on Earth. Published in 1945, it follows Out of the Silent Planet and Perelandra, although its plot differs from those books by concentrating on a sinister modern institution and events in England.

The novel combines science fiction, satire, myth, and Christian themes. Its fictional organization, the National Institute of Coordinated Experiments, presents a vision of technocratic power detached from moral responsibility. The story also draws on Arthurian material, including the figure of Merlin.

Readers sometimes assume the trilogy remains entirely in outer space because of its title. In fact, the third novel brings the conflict back to Earth. The sequence is therefore best remembered as a connected cosmic and theological project rather than a conventional three-part space adventure.