The Mercy of Gods - James S. A. Corey

The Carryx - part empire, part hive - has waged wars of conquest for centuries, destroying or enslaving species across the galaxy in its conflict with an ancient and deathless enemy. When they descend on the isolated world of Anjiin, the human population is abased, slaughtered and put in chains. The best and brightest are abducted, taken to the Carryx world-palace to join prisoners from a thousand other species. Dafyd Alkhor, assistant to a prestigious scientist, is captured along with his team. Even he doesn't suspect that his peculiar insight and skills will be the key to seeing past their captors' terrifying agenda. Swept up in a conflict beyond his control and vaster than his imagination, Dafyd is poised to become humanity's champion - and its betrayer. This is where his story begins.