This book was almost more horror than sci-fi! The sense of unease and dread I felt were palpable at parts! Area X has been cut off from the rest of the world for decades and attempts to go in and explore this un-explainable habitat filled with beautiful vegetation have proved to be fatal. Eleven expeditions have gone to try and map, study, and explore the area and have all been met with death. The twelfth expedition is composed of five women and this novel is told through the perspective of the biologist who was motivated to come after her husband died on the previous expedition. As the biologist tries to understand this hauntingly beautiful landscape and explore an unmarked tunnel into the earth, things start to veer of course. You can't trust everything you see. I'll definitely be continuing with this trilogy. I have to know what in the hell is going on!