Which C.S. Lewis novel features the demon Screwtape writing advice to his nephew Wormwood?

The C.S. Lewis novel featuring the demon Screwtape advising Wormwood is The Screwtape Letters.

The book is structured as a series of letters from Screwtape, an experienced demon, to Wormwood, his inexperienced nephew. Screwtape offers strategies for tempting a human patient, while Lewis uses the reversed viewpoint to examine pride, distraction, self-deception, and moral choice.

Lewis wrote the work during the Second World War. The letters first appeared in serialized form in the Anglican newspaper The Guardian in 1941, and the complete book was published later that year. The satirical format makes the reader infer the author’s moral argument from demonic advice. Its unusual premise has made it one of Lewis’s most widely recognized works outside the Narnia series.