A young pregnant woman named Lucia lives secluded in a remote hut in the middle of a forest with her grandmother, a mysterious and somber silent old woman, who communicates with her through enigmatic and philosophical notes. Lucia arrived at the inhospitable home of her grandmother escaping from a tortuous past: she was part of a sect formed of satanic Black Metal fans, who have been making a series of crimes. But, more than from that past, she fled from a more imminent danger: the Black Monk, the dark and ruthless leader of that sect and father of the baby she’s expecting, who plans to murder her and her child, in the framework of a diabolical ritual.
Believing she is in a place that none of her former colleagues know, and with the Black Monk imprisoned for one of the crimes he committed, Lucia lives her stay in the house thinking she is safe. But she wanders through her pregnancy with grief, tormented by nightmares and memories that reveal what she has done with the people of the sect, and pissed off by the tense relationship she has with her strange grandmother.
One day, Lucía meets Gerónimo, a disturbed young man who lives in the nearest town. He becomes obsessed with her and finds out about her past. But when he tries to approach Lucía and she rejects him, Geronimo decides to tell the news on her whereabouts to Burzum, a faithful disciple and right hand of the Black Monk. Once they know where Lucía is, Burzum and the rest of the members of the sect build up a plan to release their leader from prison and then go to the hut where she is hiding, in order to carry out the diabolical ritual that the Black Monk planned to perform with her and her unborn son. Cornered, Lucia and her grandmother must resist the attack of the violent black metal guys, if they want to stay alive.