Which C.S. Lewis novel takes the form of letters from a senior demon to his nephew?

The Screwtape Letters is the C.S. Lewis novel written as letters from a senior demon to his nephew.

The book consists of correspondence from Screwtape, an experienced demon, to Wormwood, an inexperienced tempter. Screwtape advises Wormwood on how to influence a human patient and prevent that person from developing Christian faith and virtue.

Lewis published the work in 1942, during the Second World War. Its unusual viewpoint allows him to discuss temptation, pride, distraction, resentment, and spiritual self-deception indirectly. The demons’ advice is intentionally unreliable: readers are expected to recognize the moral errors hidden inside their confident instructions.

The book was originally published in installments in the Anglican newspaper The Guardian before appearing in book form. Its epistolary structure and satirical tone distinguish it from Lewis’s more direct apologetic works.