The Day of the Dead. El Dia de los Muertos. That time of the year when Mexico celebrates its lost loved ones. But two people aren't celebrating. Nick Vargas, a disgraced newspaper reporter, now true crime writer, seeks the truth behind the slaughter of nuns in a house near the Texas border. And Hannah Freeman, a beautiful prosecuting attorney on holiday from Southern California has lost someone very precious to her — her younger sister, Jen, has disappeared without trace in Ensenada, Mexico. The realization that a sinister cult is at work and that they are behind Jen's disappearance leads them to a small town in Mexico full of dark secrets and deadly rituals, and a series of haunted caves, where something or someone lurks. Watching them. Waiting for the right moment to strike.