In a brief preface, C.S. Lewis says he discovered the bundle of Screwtape’s letters somewhere, but will not say how he managed to come across them. Screwtape is a devil, he warns the reader, and Screwtape’s version of events, therefore, should not be taken as the truth. Then the letters begin. In them, Screwtape advises his nephew, Wormwood, on how best to tempt a British man, called only “the Patient,” into sin and, eventually, into Hell. Wormwood is an inexperienced devil, and he hasgone to a training college to help prepare him to tempt humans into sin. Screwtape complains, however, that this college has taught Wormwood nothing because of its incompetent director, Slubgob. By the second letter, readers learn that the Patient has converted to Christianity and has begun going to church. The Patient is most likely in his mid-thirties and he lives with and takes care of his aging mother.
The Patient’s mother is a difficult woman. She makes many demands on the Patient’s time and energy. In the early letters, Screwtape advises Wormwood to make the Patient think that being Christian is an internal, spiritual thing rather than an external way of being in the world. After the Patient prays, Wormwood should make him fight with his mother about insignificant details about the house and chores. Over the course of these early letters, the dynamic between Screwtape and Wormwood begins to take shape. Wormwood keeps himself invisible as he follows the Patient around on Earth. He essentially whispers in the Patient’s ear, encouraging the Patient to experience negative emotions and to pursue unhealthy distractions. Unlike Wormwood, Screwtape is an experienced tempter. He has already won souls for Hell. This has earned him, it seems, a mid-management position in Hell’s vast “Lowerarchy”—a devilish corporation that determines how best to organize Hell’s temptation strategies on Earth.
After World War II begins, the Patient worries about whether he will be drafted. Screwtape advises Wormwood to exploit the Patient’s uncertainty, and soon, there is a period of relative inactivity during the war. During this time, Patient makes new, unnamed friends. These friends, however, are not Christians. They are skeptical and worldly. Screwtape advises Wormwood to make the Patient a hypocrite. The Patient should think he is better than his fellow, humble churchgoers because he has such smart and sophisticated friends, and he should think he is better than his friends because he, unlike them, is a Christian. As a result of the negative influence of these friends on the Patient, Wormwood, very briefly, seems to be doing a good job winning over the Patient’s soul. Soon, however, after reading a book and going on a walk by an old mill, the Patient experiences a reawakening of his faith. This reawakening amounts to a second conversion, and, during it, the Enemy—God—forms a barrier of grace around the Patient that appears to Wormwood as a noxious fog.
After the Patient’s second conversion, Screwtape advises Wormwood to tempt the Patient with sexual pleasures. Screwtape instructs Wormwood to make a list of all the young women in the Patient’s neighborhood that would prove to be bad marriages matches for the Patient. But the Patient falls in love withthe Woman. A Christian girl a Christian family, the Woman has a tremendously positive influence on the Patient’s life. Screwtape hates the Woman. During this time, Wormwood reports Screwtape to Hell’s secret police because Screwtape writes that the Enemy really loves humans. In Hell, this claim is heresy. It contradicts Hell’s essential teachingthat the Enemy’s love is a lie that the Enemy uses to mask His self-interest. Wormwood continues to make poor progress with the Patient and, during an episode of intense anger, Screwtape transforms into a giant centipede. This is a normal occurrence, he , an outward manifestation of his inner “Life Force.” is able to clear his name with Hell’s authorities by explaining that he was only speaking of the Enemy’s love for humans as an analogy for the Enemy’s incomprehensible preoccupation with humankind.
World War II, meanwhile, grows active again. The Germans begin to drop bombs on the Patient’s unnamed hometown. The Patient’s unspecified duties place him in harms way, and he soon begins to fear for his life. Screwtape advises Wormwood to exploit the Patient’s cowardice, but not to the extent that the Patient prays for help with it. During one bombing, the Patient acts according to his duty. Because he is afraid, however, the Patient feels himself to be a coward. This is bad news for Wormwood, Screwtape says. It keeps the Patient humble. Screwtape warns Wormwood that the Patient’s soul is prepared for Heaven, and he advises Wormwood to keep the Patient alive as long as possible. That way, Wormwood can use the Patient’s whole life to tempt him away from the Enemy and into sin. But the Patient dies during a German air raid, and his soul is taken into Heaven. Because of his failure, Wormwood must take the Patient’s place. Wormwood begs Screwtape for mercy, but Screwtape laughs, saying there is no mercy in Hell. Screwtape concludes the final letter by saying how excited he is at the prospect of eating Wormwood alive.