Which C. S. Lewis book tells the story through letters from a senior demon to a junior tempter?

The Screwtape Letters is the C. S. Lewis book told through letters from a senior demon to a junior tempter.

Published in book form in 1942, the work consists of correspondence from Screwtape, an experienced demon, to his inexperienced nephew Wormwood. The letters advise Wormwood on how to tempt a human being, allowing Lewis to examine moral weakness, distraction, pride, and spiritual self-deception from an intentionally reversed viewpoint.

The unusual format can cause confusion with Lewis’s other theological books. Mere Christianity develops Christian belief through radio talks and essays, while The Great Divorce is a fictional afterlife journey. The Screwtape Letters is both satirical and apologetic: its demonic narrator is not a guide to evil but a device for exposing it.