A scientist stationed in the remote South American jungle uncovers a lethal, unknown species that threatens his life and the integrity of his research. Owen Dawnay, an agricultural researcher, seeks to improve local farming conditions, but his isolation is shattered when he encounters a predatory, humanoid species in the dense forest. He must navigate the physical dangers of the terrain while attempting to document and survive the attacks of these creatures. The narrative unfolds through a first-person perspective, detailing his descent from scientific curiosity into a desperate struggle for survival against an apex predator.

Readers frequently highlight the effective use of isolation to build suspense throughout the narrative. Discussion often centers on the author's ability to blend scientific inquiry with visceral horror elements. Critics note that the pacing remains steady, focusing on the protagonist's methodical approach to his surroundings before the situation turns violent. Many readers appreciate the grounded, realistic tone that contrasts with the fantastic nature of the antagonists. The book is often cited for its atmospheric depiction of the South American wilderness.