The Screwtape Letters is a work of fiction by C._S._Lewis, purporting to be a collection of letters from a senior devil (Screwtape) to his nephew Wormwood, a junior devil (we do not see Wormwood's replies to Screwtape). Screwtape gives advice to Wormwood on how to secure the damnation of a human (known as 'the Patient'). After the first letter, the Patient is converted to Christianity, and Wormwood is given a severe rebuking. Wormwood's aim is now to undermine the Patient's faith as well as to tempt him to explicit sins.
In the last letter, it emerges that the Patient dies during an air raid in London during the Second World War, and he goes to Heaven. Wormwood is punished for his lapse by being given to Screwtape to eat.
While the Screwtape Letters is one of Lewis' most popular works, Lewis himself claimed that the book was both easy and distasteful to write. He vowed never to write a direct sequel for this reason, although he did write an essay entitled Screwtape proposes a toast, in which Screwtape gives an after-dinner speech to the College of Tempters.