Which C.S. Lewis novel features the demon Screwtape as a senior tempter?

The Screwtape Letters features the demon Screwtape as a senior tempter.

The Screwtape Letters is a satirical Christian novel presented as a series of letters from Screwtape, an experienced demon, to his inexperienced nephew Wormwood. Screwtape advises Wormwood on how to tempt a human known only as “the Patient.” Lewis uses the reversed viewpoint to expose vanity, distraction, self-deception, and other habits that can damage a person’s moral life.

The letters first appeared in the Anglican newspaper The Guardian in 1941 and were published as a book later that year. Lewis dedicated the work to his friend J.R.R. Tolkien, although their friendship was not always free of disagreement.

The book is fiction and satire, not a theological handbook claiming to report literal demonic correspondence. Its unusual narrative voice is the central device: readers are invited to recognize familiar human weaknesses by hearing them praised from a demon’s perspective.