Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great historical novel, intense mystery

I don't even like mysteries, but I loved this book. The plot is superbly woven and provides a unique chance to learn something interesting about a little-known niche of Hitler's war. The book is literally a page-turner in both the sense of its tense drama but also because it drove me to want to learn more and more about what was going on in Portugal during WW2. The character development was deep and honest and the dialogue was very rich and realistic. I thought Wilson did an excellent job balancing the 2 stories and bringing them together, which was not likely an easy thing to do.I can't believe some people thought the plot was too complex or hard to follow. If your idea of endulging in a complex mystery is watching "Matlock" reruns, then you will probably be stumped by this book. But if you like to learn and think while you have fun reading, then run out and get this book.