In 1946, as London emerges from the shadow of World War II, author Juliet Ashton is having a terrible time finding inspiration for her next book. Then she receives a letter from Guernsey Island, and learns of a unique book club formed on the spur of the moment as an alibi to protect its members from arrest by the occupying Germans during the war. Captivated, she sets sail for Guernsey, and what she finds there will change her life forever.

In the early twentieth century in Swampsea, seventeen-year-old Briony, who can see the spirits that haunt the marshes around their town, feels responsible for her twin sister's horrible injury until a young man enters their lives and exposes secrets that even Briony does not know about.