Screwtape’s letters form the title of C.S. Lewis’s 1942 book The Screwtape Letters.
The work is a series of fictional letters from Screwtape, a senior demon, to his inexperienced nephew Wormwood. Screwtape advises Wormwood on tempting a human patient, while Lewis uses the reversed viewpoint to satirize moral weakness, self-deception, distraction, and bureaucratic thinking.
Lewis wrote the book during the Second World War. It first appeared in the Anglican newspaper The Guardian, where installments were published in 1941; the collected book followed in 1942. The unusual format lets Lewis discuss Christian ethics indirectly rather than presenting a conventional theological treatise.
Wormwood is the junior demon receiving the advice, not the character named in the title. That distinction is a common source of confusion. The title identifies the senior correspondent, Screwtape, whose letters supply the entire structure of the book.