It's 2011, in Madrid. Professor Fuentes (Miguel Ángel Jenner) is tying five Medicine students up to chairs. He explains methodically that he is going to make an experiment above the power of the mind, and subsequently he asks for a volunteer without specifying what for. José "Jose" Aguas (Maxi Iglesias) is so cocky that he becomes sort of nominated by the rest of the students. Professor Fuentes shows them an emergency cabinet and a penknife, and he cuts Jose in one of his arms, saying that Jose has the mental power of stopping himself from bleeding to death. If he doesn't succeed, he will die, because he had cut him through one of the main arteries of the body. The students start to scream, snobbish Belén (Úrsula Corberó) threatens Fuentes to tell her father, but nobody can prevent Jose from having a fit.
The momentum is broken. Toni (Óscar Sinela), who has been drescribed as a friqui - which in Spanish means a mixture of freak and geek - starts laughing, saying that the rest should have seen their own panicky faces.Fuentes explains that the mind can send a symptom to oblivion, but it can also create it. There was a surgery bag with pig blood attached to the chair, and when Fuentes cut it, it started to release the blood little by little. Jose wasn't even scratched with the penknife. Jose tries to punch Toni, but the rest prevent so. Fuentes picks up his stuff and leaves, reminding them of next week's examinations and saying that the future surgeons have to learn to remain calm, cool and collected in the future.
Ángela (Amaia Salamanca) runs after Fuentes: he had promised her that there will be no final examination for those who would be the Guinean pigs in the experiment. First, Fuentes congratulated her, because she was the only one who was not panicky, and then he tells her that he hopes that she has learned something, and that the experiment will help her in the future. He also reminds her that she is about to lose her grant because she is about to fail his subject. A folder of newspaper cuts fall to the floor, and Ángela sees that is about a ghost town called Susurro. Fuentes asks her whether she believes in the paranormal, and she says she doesn't. He tells him that the town lived from some salt mines which were reopened in the 1960's, but that miners ended up refusing to work on them, as they were stalked by Dr. Matarga (Manuel de Blas), a doctor who killed even after he was dead. The town died out at the same time that the mines. Ángela proposes Fuentes to make a scientific study of the town and to prove once and for all that everything is on the mind of the people. Fuentes immediately agrees, and he tells her that she has up to the day of the exam, and that, if she succeed, they can talk about her marks.
Ángela leaves Fuentes' office and she is startled by the cleaning man. She is pulled aside by her boyfiend Carlos (Lucho Fernández), who has stolen a belt from the experiment office. She tells him that he's childish, and then proceeds to tell her friends about the idea. Belén is the most concerned, and Toni offers to bring the equipment they need for the research. Carlos wants to get rid of him, but Ángela realises that they will need his help.
To transport themselves and all the equipment to Susurro, Ángela asks her little sister Diana (Alba Ribas) to lend her her van. Diana doesn't even want to give her a kiss in the café where she works. Ángela notices her father's watch on Diana's wrist, but she says it doesn't anger her, it's only that there is nothing good to remember about him. At first, Diana refuses to lend her her van, as she needs it, but Ángela tells her that she doesn't really need it, as she is always at work, and that she's not really critisizing her for it. Flashback of the two women when they were girls and they would play with their dollhouse. Their executive-looking dad (Eduard Farelo) arrives home and plays with them. Back to 2011, Diana is alone at the café after the conversation with her sister; she goes to the public restroom and cuts one of her wrists, applying some tissue right afterwards: that's why she was wearing her dad's watch.
Back home, Carlos complains that Ángela never tells him anything. They make out and he uses the stolen belt to tie her hands. At that moment, Diana calls her up and agrees to take them there. When they resume lovemaking, it's Ángela who ties Carlos up. Jose tries to impress Diana with his motorbike, but she thinks she's an asshole. They all meet outside the nautic club. Belén complains because the blue van is quite... a heap of crap really, although it serves its purpose.
They stop at an oil station, and Toni proves to be jealous of anybody meddling with the equipment apart from himself. Belén wants to go to the cemetery directly, but Ángela decides to go to the mines, because Matarga used to put there the corpses, as the salt would preserve the bodies. Toni mentions that Matarga used to torture first, and Diana admits that she sometimes feels a pressence, an energy around her. Toni says that the townspeople discovered mutilated bodies at Matarga's home, so they put him into the salt mines to die, and that when they reopened, his corpse couldn't be found anywhere.
They go through a path and arrive to Susurro, with empty buildings all around. Jose keeps on playing with the camera, and the group is going to spend the night in the old church, as it is in the town center and it will protect them from the bad spirits - as Toni argues.
They decide to go around the town in pairs. Belén would rather stay behind "taking care" of their things - in reality, playing games in her cell phone, but Toni drags her outside with him. Jose tries to chat with Diana about her relationship with Ángela - she says that when their dad committed suicide, they went from one home to another, and that they now lead separate lives. Belén and Toni enter the old meat-processing factory, and Ángela and Carlos go to the mines. There is a locked rail in the mine; they burst it open and enter. Diana gets in a trance-like state, and she hears some screams in the wind. Toni has recorded a kind of muted screams and laughter and says that people which had been through traumatizing childhoods are more receptive to certain stimuli. At this point, Belén wants to leave, but as Diana's vote counts double, they have to stay. The new objective is to prove that there is a ghost in the town.
Diana volunteers to enter a hypnotic trance through the symbols, with Toni controlling her. The universe kinda spirals out of the laptop towards her, and amid the mist, there appears Dr. Matarga. He has got only one eye and asks her whether she is really sure that she wants to remember the reason for the scars. He opens them up and they start to bleed. He says that when the door is opened, there is no turning back. He appears behind the frozen students, and he caresses Ángela's hair, making a gesture of cutting her jugular.
Diana wakes up hysterically, and tells Ángela that a man wants to hurt her. Toni shows a picture to her, and she recognises Magarta. Belén wants to leave again, but Jose tells a bad joke to make them laugh, about a boy who everybody picks on him because he's an orphan, and when he tells his parents, only the echo listens to him. The moment is broken and they all stay. Ángela talks to Diana, telling her that she's lucky she doesn't remember having seen her father kill himself, because she did. She offers to see her little sister oftener, and at that moment, Carlos calls them up.
They visit the doctor's home; as soon as they enter, a rat startles Belén. Everybody goes up the stairs except for Diana, who goes to the left of a huge corridor. Diana enters a sitting room, and behind the curtains, she moves down a small corridor to the room where Dr Matarga used to torture people. Carlos appears to call her up, as they should be in only one group. Carlos tries to kiss her, but she steps back: Carlos says that he's turned on. Suddenly, Dr Matarga is behind him, and Carlos is put on the torture rack hastily, tied up with wire. Diana tries to interfere but Matarga pushes her against a shelf of things. Matarga makes cynical comments, telling Carlos that this is a situation from which he cannot escape. Diana starts remembering herself with Ángela as children, happily drawing and painting. Their dad would put the food in front of them in anger, and he would shout to them and push the table upside down when they didn't feel like eating, apparently out of sadness for the death of his wife.
Ángela wakes Diana up. There is fresh blood on the torture table, but Carlos is not there. Diana says that Matarga took him, but Ángela tells her that only they six are on the place. The remains of blood lead Ángela to a secret corridor which links the room to the salt mines. Ángela insists on the need for everybody to stay together. They think they hear Carlos down a corridor and they go there. They find Carlos still alive, with a hook on his left eye and still tied with wire. Ángela tells Diana to go to the van and ask for help; finally, she reacts and leaves with Belén tagging behind. Ángela is the one who has to take the long spike out of Carlos' head.
Belén and Diana reach the van, but there is a flat tyre, and the van won't start. Diana feels Matarga saying "Come with me" to her, and tells Diana to run, but she doesn't obey, saying that there's nobody there. Diana runs and sees Matarga walking towards her, so she runs inside a building. The rest are taking Carlos inside the church, and try to patch him up with bandages. Belén runs to the church, tells the rest what has happened and says that she doesn't know where Diana is. Jose offers to go searching for her. He records a goodbye message on the camera for his family, while Diana returns to the torture room. She cuts herself with some broken glass. Matarga approaches her almost tenderly and tells her that that's only the beginning. Jose appears at that moment, and Diana tells him that Matarga is in the room. Jose tries to calm Diana down, and hugs her, saying that if they have something together Ángela is going to kill him, and that that is precisely what scares him most.
At that moment, Matarga puts a hook through his mouth saying "why don't you ever shut up?" He is so strong that he can tear his head in two. Diana remembers her big sister defending her from her father, and being beaten by her dad with a belt in turn while Diana as a child would see it from the stairs; she gets out of her trance-like mood and she screams. The rest hear it because the door in the church opens up on its own, letting the sound reach them. Ángela and Toni go to see what's happened. Belén is alone at the church with Carlos, but she tells him that she is going to change the tyre. Belén swiftly does so and leaves in the van.
Ángela and Toni find Jose hanging from a hook with the face tied up with wire. Diana is not around. Belén is finding hard to concentrate while driving on the misty night. The radio turns itself on, and she sees somebody standing on the middle of the path (it looks like Diana). Belén turns right and bumpts onto a tree. Matarga appears and pulls her out of the van. He makes a comment "why are you in such a hurry?", and then he says that her face shows she used to be a beauty pageant winner, and pushes her head onto the broken glass, killing her. Then, he says that she had a beautiful ass. Matarga looks at Diana and she remembers how she hid behind some boxes, but that her dad found her and pulled her out; as things fell down, they hit on dad's head, leaving him a bit dizzy.
Ángela and Toni return to the church. They look at the camera's recordings: it shows Jose consolling Diana, and then she attacks him, saying "why don't you ever shut up?". Ángela can still not believe it. She feels guilty because she was so busy moving on that she left her sister behind. Toni mentions that it may be a case of possession, but Ángela only believes in schizophrenia, blames Toni because of the hipnotic session gone awry and insists that ghosts don't exist. However, Toni says that he has been waiting all his life to see something like that, that he is going to search for Diana.
Diana comes back to the first sitting room shouting "You wanted me, didn't you? Here I am!" Matarga is on the ceiling. There is a breeze from behind the curtain, and she goes down to the torture room. Diana talks to Matarga, who tells her to remember, and says that everybody tricked her about her dad's death. Toni arrives, trembling with fear. He sees Diana from behind, talking to no one. When she turns around, she attacks him: Diana and Matarga have become one, even doing the same movements. Diana slashes Toni's fingers and his neck and says with Matarga's voice "Careful with what you wish for. It may come true."
Ángela appears, running. She hugs her, and then, Diana finally remembers how she put a bullet straight onto her father's head. Diana says that Ángela should have really told her how badly their father used to treat them, but Ángela said that she couldn't take away her happy reminiscences. Matarga appears and stabs Ángela, but Diana tries to put a stop to it. Matarga asks her "what are you going to do to stop me?", so that Diana cuts her own throat. As a result, Matarga also bleeds to death. Ángela hugs Diana as she dies.
Ángela is walking, wounded. She has arrived to the oil station at the beginning, but there is nobody there. In the garden of a psychiatric institution, Ángela tells Fuentes that she has learned there are things she cannot explain. Fuentes replies back that the police are clearly thinking that Diana was the murderer, and expresses his wish that she would contunue her studies in the future. Fuentes also gives her a small envelope and leaves.
Ángela sits next to a patient in a bench and opens the envelope: there is dad's watch inside. A doctor (Manuel de Blas) appears from behind her and, speaking with Matarga's voice, tells her that remembering what happened will be her burden all her life, and that he can't think of a better torment. Terrified Ángela watches the doctor in a white coat smile.
---written by KrystelClaire