March 1912: Twenty-four-year-old Elspeth Dunn, a published poet, has never seen the world beyond her home on Scotland's remote Isle of Skye. So she is astonished when her first fan letter arrives, from a college student, David Graham, in far-away America. As the two strike up a correspondence -- sharing their favorite books, wildest hopes, and deepest secrets -- their exchanges blossom into friendship, and eventually into love. But as World War I engulfs Europe and David volunteers as an ambulance driver on the Western front, Elspeth can only wait for him on Skye, hoping he'll survive ... June 1940: At the start of World War II, Elspeth's daughter, Margaret, has fallen for a pilot in the Royal Air Force. Her mother warns her against seeking love in wartime, an admonition Margaret doesn't understand. Then, after a bomb rocks Elspeth's house, and letters that were hidden in a wall come raining down, Elspeth disappears. Only a single letter remains as a clue to Elspeth's whereabouts. As Margaret sets out to discover where her mother has gone, she must also face the truth of what happened to her family long ago.