What is the title of C.S. Lewis’s book about a demon advising his nephew?

C.S. Lewis’s book about a demon advising his nephew is The Screwtape Letters.

The book is structured as a series of letters from Screwtape, an experienced demon, to Wormwood, a younger tempter. Screwtape gives advice about how to undermine a human being’s faith and moral life. Lewis uses the fictional correspondence to satirize temptation, pride, distraction, and self-deception.

The letters first appeared as a series in the Anglican newspaper The Guardian in 1941. They were collected and published as a book later that year. Lewis dedicated the work to his friend J.R.R. Tolkien, although the two writers disagreed about its tone.

A common mistake is to treat the book as a conventional story told from a demon’s point of view. Its epistolary form and deliberately inverted moral perspective are central to its design: readers infer the author’s ethical argument from Screwtape’s advice.