Though her mind is still sharp, Elizabeth's bones have aged and her eyes have failed. No longer able to linger over books or gaze at paintings that move her spirit, she fills her days at the retirement home with music and memories of her family, especially of her beloved twin sister, Emily. When her late father's journals are discovered after a accident, she seizes the opportunity to piece together the mysteries of her childhood. With the help of Morgan, a delinquent teenager performing community service at the home, Elizabeth delves into the diaries - a journey that brings the two women closer together, to Porphyry Island where Elizabeth's father served as lighthouse keeper and raised his young family in the years before and during World War II. As a web of secrets unravels, Elizabeth and Morgan realize that their fates are connected to each other and to the isolated island in ways that are heartbreaking and healing.