What was the name of C.S. Lewis's 1942 book of fictional letters from a senior demon to a junior tempter?

The Screwtape Letters is C.S. Lewis’s 1942 book of fictional advice from a senior demon to a junior tempter.

The book consists of letters written by Screwtape, an experienced demon, to his nephew Wormwood. Screwtape advises Wormwood on how to undermine a human patient’s faith and character. Lewis uses the inverted viewpoint to expose temptation, self-deception, distraction, and pride.

The concept began as a wartime publication. Lewis wrote the letters during the Second World War, and they first appeared in the Anglican newspaper The Guardian before being collected as a book in 1942. The unusual format makes the work satirical, theological, and psychologically observant at the same time.

The senior demon’s title is often confused with the name of the junior tempter. Screwtape is the adviser, while Wormwood is his inexperienced nephew. Lewis later wrote a preface explaining some of the hazards of imagining demonic correspondence.