The Light Between Oceans

Tom Sherbourne, a traumatised and withdrawn hero of World War I, is hired as a lightkeeper at Janus Rock, a lighthouse off the coast of Western Australia. He falls in love with a local girl, Isabel Graysmark, and they marry in 1921. Isabel loses two pregnancies in three years, and fears she may never become a mother. Shortly after Isabel's second miscarriage, a rowboat containing a dead man and a newborn baby girl washes up on the shore near the lighthouse. Tom knows that regulations require him to report the discovery. However, Isabel fears that the baby will almost certainly be sent to an orphanage, and persuades Tom to pass the baby off as their own. Tom grudgingly agrees. He buries the man on the island and they name the girl Lucy. Read more on Wikipedia.