The Screwtape Letters is a book written by author and Christian scholar C. S. Lewis. It appeared in installments in "The Guardian" newspaper and was later published as a book in 1942. It is a series of letters written by a devil named Screwtape to his apprentice and nephew Wormwood. The letters are filled with advice for the young demon on how to tempt men. Screwtape tells Wormwood how to undo the work of God and work against Him.