What was the title of C.S. Lewis’s 1942 book written as letters from a demon to his nephew?

C.S. Lewis’s 1942 book written as letters from a demon to his nephew is The Screwtape Letters.

The book presents a series of fictional letters from Screwtape, an experienced demon, to his inexperienced nephew Wormwood. Screwtape advises Wormwood on how to tempt a human subject and undermine the person’s spiritual life. The correspondence is satirical: Lewis reverses the usual viewpoint so that moral failure is described as demonic professional advice.

The work began as a series published in the Anglican newspaper The Guardian in 1941. The collected book appeared in 1942. Lewis later dedicated it to J.R.R. Tolkien, though Tolkien reportedly disliked the dedication because he did not enjoy the book’s satirical method.

The Screwtape Letters is not a conventional novel with a continuous plot. Its epistolary form lets Lewis explore habits, distractions, pride, self-deception, and temptation through an intentionally comic but unsettling voice.