Oh boy. Well what comes to mind first is Sebastian Japrisot's A Very Long Engagement, about a young woman trying to find her fiance in the wreck of post World War 1 France. It has a wonderful, bittersweet happy ending that makes me tear up just thinking about it. Another good one along those lines is Possession, by A.S. Byatt, about two British academics researching the lives of two Victorian poets. The kicker in that book is what they don't find out but we do. Still gives me shivers!