The Light Between Ocean: a novel is M. L. Stedman's first novel. The action is set in western Australia, mainly on Janus Rock, a small island with a lighthouse and no human inhabitants other than the lighthouse keeper, and when he has one, his family.
It's soon after "The War to End All Wars", which later became known as World War I. Tom Sherbourne has returned from the war and is having trouble finding an inner peace. But the quiet routine of lighthouse keeping helps to soothe him. And Isabel Graysmark breaks through the isolation he's built around himself, convincing him that marrying her would be good. Unlike some for whom the war broke inhibitions against unlawful behavior, for Tom it reinforced the sense that morality and ethics are key to a good and civilized life.
After a few years of living on Janus Rock with a supply ship visiting every six months and a break onshore every two years, a boat washes up on their shore one day. The choices they make that day have a profound effect on Tom, Isabel and the closest supply town, Partageuse.