Seven American scientists push deep into one of the last untouched corners of the Peruvian Amazon to study a dying forest and document peoples who have never known the outside world. The first days are wonder itself: unknown species, crushing beauty, campfires beneath the canopy.

Then their equipment moves on its own. Bare footprints?far too wide?ring the camp. A monkey is found gutted and arranged, like a message left behind.

When the first of them vanishes, the team understands too late that they are no longer the observers. Something is hunting them?studying them, isolating them, taking them one at a time. Not an animal. A man, the last of a people erased from the earth, who sees in them the invaders who destroyed his world. One by one, he hunts them through the endless green, with no rescue, no signal, no contact.

Elena Ferreira, a psychologist, will keep the journal of their unraveling. To survive, she must learn to think the way he does?and find out how far down she is willing to go to come back out alive.

A work of pure, realistic, relentless horror, in which the jungle itself becomes a character.