London, January 1946, emerging from the shadow of the Second World War, writer Juliet Ashton is looking for her next book subject. She finds it in a letter from a man she's never met, a native of the island of Guernsey, who has come across her name written inside a book by Charles Lamb. As Juliet and her new correspondent exchange letters, Juliet is drawn into the world of this man and his friends. The Guernsey Literary and Potato Peel Pie Society was born as a spur-of-the-moment alibi when its members were discovered breaking curfew by the Germans occupying their island.