It's 1946 and author Juliet Ashton can't think what to write next. Out of the blue, she receives a letter from Dawsey Adams of Guernsey - by chance, he's acquired a book that once belonged to her - and, spurred on by their mutual love of reading, they begin a correspondence. When Dawsey reveals that he is a member of the Guernsey Literary and Potato Peel Pie Society, Juliet's curiosity is piqued and it's not long before she begins to hear from other members. As letters fly back and forth with stories of life in Guernsey under the German Occupation, Juliet soon realises that the society is every bit as extraordinary as its name.