This is more than a combination of thriller and "hard"SF. It is a true novel, a major piece of literary SF that should have received the Hugo or the Nebula or both. Unfortunately, the author is known as a creator of fantasy, so this gem has not received the attention it should have. It is a most readable work of art, never leaving a chance for a yawn. But it is also a complex work, which gives away more after a second or third reading.