Which C.S. Lewis novel is written as letters from a senior demon to a junior demon?

The Screwtape Letters is the C.S. Lewis novel written as letters from a senior demon to a junior demon. It was published in book form in 1942.

The senior demon, Screwtape, writes to his nephew Wormwood, who is trying to influence a human subject. The letters reverse the usual viewpoint of religious instruction: temptation, pride, distraction, and self-deception are discussed from the perspective of Hell’s bureaucracy.

Lewis uses this reversal for satire as well as moral analysis. Screwtape’s confident advice often exposes the absurdity and danger of the habits he recommends. The book’s epistolary structure lets each chapter focus on a particular spiritual or psychological problem without following a conventional adventure plot.

The work began as pieces published in the Anglican newspaper The Guardian. Lewis later dedicated it to his friend J.R.R. Tolkien, though the two writers differed in style and theological emphasis. A common mistake is to call Screwtape the junior demon; he is the senior correspondent, while Wormwood is his inexperienced nephew.