What was C.S. Lewis’s final completed novel in the Space Trilogy?

That Hideous Strength was C.S. Lewis’s final completed novel in the Space Trilogy. Published in 1945, it follows the struggle surrounding the fictional National Institute of Coordinated Experiments, or N.I.C.E.

The trilogy begins with Out of the Silent Planet, published in 1938, and continues with Perelandra in 1943. While the first two books focus strongly on interplanetary settings, That Hideous Strength takes place largely on Earth. Its plot combines academic ambition, technological control, bureaucratic power, and supernatural forces.

The novel is sometimes called a science-fiction book, but its setting and tone differ significantly from those of its predecessors. Lewis also connected it with themes found in his nonfiction work The Abolition of Man. The title echoes a line from Sir David Lindsay’s sixteenth-century poem A Redemptive Treatise of Man’s Redemption. The trilogy is also known as the Ransom Trilogy, after its protagonist, Elwin Ransom.