Space Trilogy: 75Th Anniversary Edition by C.S. Lewis

OUT OF THE SILENT PLANET Dr Ransom, a Cambridge academic, is abducted and taken on a spaceship to the red planet of Malacandra, which he knows as Mars. His captors are plotting to plunder the planet's treasures and offer Ransom as a sacrifice to the creatures who live there...

PERELANDRA Having escaped from Mars, Dr Ransom is called to the paradise planet of Perelandra, or Venus. When his old enemy also arrives and is taken over by the forces of evil, Ransom finds himself in a desperate struggle to save the innocence of this Eden-like world...

THAT HIDEOUS STRENGTH Investigating the truth about her prophetic dreams, Anne Studdock encounters the fabled Dr Ransom, who is in great pain after his travels. A sinister society run by his old adversaries intends to harness the ancient powers of a resurrected Merlin in their ambition to subjugate the people of Earth...