Which C.S. Lewis work is the final volume of his Ransom Trilogy?

That Hideous Strength is the final volume of C.S. Lewis’s Ransom Trilogy.

Published in 1945, That Hideous Strength concludes the trilogy that began with Out of the Silent Planet and continued with Perelandra. The books follow Elwin Ransom and combine science fiction, Christian theology, myth, and philosophical speculation.

The final novel moves much of its action from other planets to England. Its plot concerns the National Institute of Coordinated Experiments, or N.I.C.E., an organization whose pursuit of scientific control threatens human freedom and embodied life. The story also draws on Arthurian themes and Lewis’s concerns about technocratic power.

The title comes from a line in David Lindsay’s 1920 novel A Voyage to Arcturus. Readers sometimes call the series the Space Trilogy, although Ransom Trilogy is the name that identifies its central protagonist and avoids suggesting that every major setting is outer space.