After the death of explorer Emilio Lanzetti in 1920, allegedly at the hands of a primitive indigenous community during his search for a mythical place called the Black Rainbow, Fernando, his son and pupil, decides to embark on an expedition to continue his father's last work. His thirst for revenge and his ambition will make his journey a true descent into hell, for those lands hold a dark secret. The white man should never have challenged nature or embarked on that journey.