London, 1946. Juliet (Lily James), writer, receives a letter from a member of a mysterious club that started in Guernsey occupied by the Nazis. Juliet decides to visit the island. There he meets the eccentric members of Guernsey Literary and Potato Peel Pie, and Dawsey (Michiel Huisman), the farmer who wrote his letter. As the secrets of their past of war unfold, the course of her life will change forever.