Science Fiction. The main characters were well developed, so I sympathized with their struggles. The action flowed fast and furious, with many twists and turns, keeping me on the edge of my seat. The nemesis was totally evil, while the good guys had their faults. I wish the "bad guy" would have had some half decent qualities. Most everyone in this world is a mixture in this regard. Even Hitler loved children. The intensity, the melodrama and the suspense became wearing toward the last quarter of the book. I began wishing the resolution would have been earlier. And while there was literary skill evident, some of the efforts in that regard seemed a a bit clumsy. I'm an old English major, so maybe I'm being a little hypercritical here. But I enjoyed the book.