C.S. Lewis best known for his Narnia books wrote a trilogy.
Out Of the Silent Planet set on Mars where a British professor named Ransom and a couple of con men discover non human intelligent beings for the first time. It introduces the cast of characters in the books to follow. In this book Ransom gets a wound in his heel that never heals and plagues him though the series.
Perelandra has an Adam and Eve like couple faced with the introduction of evil by the con men from Earth while Ransom prevents them from committing Venusian original sin so that a race of unfallen beings will live in paradise on Venus.
That Hideous Strength is set on Earth where Ransom has gathered a group of Oxford Dons, little old ladies and Merlin from the King Arthur stories to battle the forces of evil and prevent the destruction of Earth. One of the main villians is a woman named Fairy Hardcastle who heads a Nazi like organization with the acronym N.I.C.E. The N.I.C.E. is employed by the British government to improve the lives of the people since they are incapable of making the right decisions themselves.