The Light Between Oceans by M. L. Stedman

The books finds you on an outer island off of Australia.  The young couple settles into a comfortable life and hopes to have a family. After several miscarriages Isabel is quite distraught. Crying is heard on the shore and a small boat has washed ashore with a baby. She convinces Tom, her husband, to keep the baby and make no note of the occurance in the lighthouse log. Over the years this becomes more and more distressing to Tom. The story unfolds, things come to light on the mainland and families are torn apart. It was hard to not feel the pain and stress of those involved.  Stedman shows the strength of the human spirit and what people will go through to protect what they think is theirs.