The last book of Lewis's sci-fi trilogy is a breakneck journey of suspense in which Dr. Ransom must choose sides in a battle between science and ethics. Like Perelandra and Out of the Silent Planet, this is a compelling work of fiction that is also, at its heart, a timeless allegory of good and evil.
The final book in C.S. Lewis's acclaimed science fiction Space Trilogy, which follows Out of the Silent Planet and Perelandra, concludes the adventures of the matchless Dr. Ransom.

Now, the dark forces that have been repulsed in Out of the Silent Planet and Perelandra are massed for an assault on planet Earth. Word is that the mighty wizard Merlin has come back to the land of the living after many centuries, holding the key to ultimate power for the force that can find him and bend him to its will. A sinister technocratic organization is gaining power throughout Europe, with a plan to "recondition" society, and it is up to Ransom and his friends to stop this threat by applying age-old wisdom to a new universe dominated by science. The two groups struggle to a climactic resolution that brings the Space Trilogy to a magnificent, crashing conclusion.

Written during the dark hours immediately before and during World War II, C.S. Lewis's Space Trilogy stands alongside such works as Albert Camus's The Plague and George Orwell's 1984 as a timeless classic, beloved by succeeding generations as much for the sheer wonder of its storytelling as for the significance of its moral concerns.