In November 1995, Ángela, Ana Torrent, a university student in Madrid, begins a thesis project on audiovisual violence and the family. Her routine commuter ride ends with a train evacuation after a man commits suicide by stepping in front of the train, and Ángela, curious and unsettled, moves toward the tracks in a tense attempt to glimpse the remains.
At the university, Ángela asks her thesis director, Professor Figueroa, [Miguel Picazo], to help her locate the most disturbing films in the library, and tracks down Chema, [Fele Martínez], a fellow student known for collecting violent and pornographic videos. While Ángela watches a violent film with Chema, Figueroa uncovers a tape hidden in the audiovisual archives, hinting at secrets buried in the school’s collection. The next day, Ángela learns that Figueroa has died in the screening room from an apparent asthma attack, and she retrieves the tape that he found. A younger professor, Castro, [Xabier Elorriaga], then takes over supervision of Ángela’s project.
At Chema’s house, Ángela discovers that the stolen tape is a snuff film showing a woman being tortured, killed, and disemboweled. Chema identifies the victim as Vanessa, a student who had vanished two years earlier, and he deduces that the killer used a specific Sony camera with a digital zoom and that the filming occurred in a garage. The case begins to feel personal as Ángela delves deeper into Vanessa’s fate.
Back in the library, Ángela spots Bosco, [Eduardo Noriega], using the same camera. She agrees to interview him under the pretense of reporting on Vanessa’s disappearance; Bosco suggests that Vanessa might have run away with a boyfriend. Chema warns Ángela that Bosco is a psychopath, a warning she tentatively takes seriously as the investigation widens.
At home, Yolanda, [Rosa Campillo], Bosco’s girlfriend, confronts Ángela and fills in the backstory: two years earlier, they had attended director’s workshops with Castro, and Vanessa was pressured to perform nude for a short film. Yolanda also reveals that Chema was once friends with Bosco and that the group’s fascination with snuff films ran deep. The confession adds layers of danger and complicity to Ángela’s quest for truth.
One night, Chema shows Ángela a hidden tunnel he has discovered in the school’s video library. In a chamber off the tunnel, they find shelves filled with tapes resembling Vanessa’s, suggesting many other women may have suffered the same fate. The door seals behind them, and they are trapped inside. They push forward with only matches for light, eventually reaching an editing room where they sleep in each other’s arms, hoping to survive the night.
When Ángela awakens, Castro is in the room and reveals that he edited the snuff videos but did not murder anyone; he plans to kill Ángela, claiming the death will be painless and far quicker than Vanessa’s. As he aims a gun at her, Chema bursts in and struggles with Castro. The gun goes off, killing Castro, and Ángela and Chema manage to escape.
Returning home, Ángela’s father informs her that Sena, Ángela’s sister, is at a party with Bosco. Terrified, Ángela hurries to the gathering, where Sena refuses to leave, insisting that Bosco loves her. To pull her sister away, Ángela approaches Bosco and kisses him passionately, a risky move that tests both sisters’ loyalty and safety.
The following day, Ángela contemplates going to the police with Chema, but Chema asks for a moment and takes a shower. While he’s inside, Ángela discovers a Sony zoom camera among Chema’s belongings containing a tape showing Ángela herself outside her bedroom window, revealing that she may have been stalked. Fleeing in panic, she returns home to warn Sena and then hails a taxi to Bosco’s house, pursued by a shadowy figure in a black raincoat.
At Bosco’s house, the mood shifts as the two talk. The power goes out, and Bosco descends to check the breakers. When Ángela follows, she finds Bosco unconscious, only for him to regain consciousness and fight back as Chema arrives, knocked out Bosco, and ties him up. Bosco then exposes a garage that matches the room in the snuff film, intending to torture Ángela. Striking back, Ángela frees herself, slashes Bosco, and shoots him dead. She then visits Chema in the hospital, where a TV news report claims that six bodies have been found at Bosco’s home. Ángela offers Chema a book inscribed with an invitation to have coffee and tells him she plans to abandon her thesis. As they depart, the announcer hints that footage from a snuff film will be aired, leaving Ángela to face an uncertain future and the moral consequences of her investigation.
