To treat a disturbed 11-year-old boy, pioneering psychiatrist Grace Burnham travels from New York to the remote Marquez Ranch in the Colombian highlands in the 1890s. Grace quickly realizes that this is no ordinary case: There were always unexplained incidents surrounding the introverted Martin. The local priest and the devout village community are convinced that the boy is possessed by the devil. When unexpected deaths occur around Martin, a catastrophe is in the offing that will turn Grace's life upside down ...