Thesis

Angela's commuter train is evacuated after a man commits suicide by stepping in front of the train. She is drawn toward the tracks, hoping to glimpse the victim's remains. The incident motivates her to pursue a thesis on audiovisual violence and the family.

At the university, Angela asks her thesis director for help locating violent films and seeks out Chema, a fellow student who collects such material. The two begin discussing sources for her project. Figueroa uncovers a tape hidden in the audiovisual archives, hinting at a darker line of inquiry.

The next day, Figueroa is found dead in the screening room from an apparent asthma attack, and Angela retrieves the tape he had discovered. The event turns the tape into a central piece of her research. Castro, a younger professor, begins supervising her thesis.

At Chema's house, Angela learns the tape is a snuff film depicting a woman's torture and murder. Chema identifies the victim as Vanessa, a student who disappeared two years earlier, and deduces the killer used a Sony camera with a digital zoom, shooting the footage in a garage.

Angela spots a handsome man named Bosco at the library and tracks him down for information about Vanessa's disappearance. During a staged interview, Bosco suggests Vanessa ran off with a boyfriend, while Chema warns that he is a psychopath.

Bosco charms Angela's family during a dinner visit, and she initially relaxes around him. That night, Chema asks security to review footage from the night of Figueroa's death, and Angela dreams of Bosco threatening her with a knife, filming the scene and stabbing her.

Yolanda, Bosco's girlfriend, explains that she and Vanessa, Bosco, Chema, and another person had attended director's workshops with Castro two years earlier. She describes a coercive dynamic and suspects Chema of involvement; Vanessa's disappearance seems linked to their past.

Chema guides Ángela to a hidden tunnel behind the school's video library. In a room off the tunnel, they discover shelves of tapes like Vanessa's, indicating many other women may have been murdered in snuff films. The door closes behind them, forcing them to press on with only matches for light.

The duo finds an editing room in the tunnel complex and fall asleep there. Ángela later wakes to Castro confronting them, claiming he only edited the snuff videos and intends to kill her, but Chema intervenes. The confrontation ends with a gunshot that kills Castro, and Angela and Chema escape.

Back at home, Angela learns Sena is at a party with Bosco. To persuade her sister to leave, Angela kisses Bosco in front of Sena, signaling the danger and complexity of her investigation. The moment cements Bosco's unsettling hold over the case.

The next day, Angela discovers a Sony zoom camera among Chema's belongings containing a tape showing Angela outside her bedroom window. Convinced Chema has been stalking her, Angela flees and seeks safety. She then heads to Bosco's house to confront him in person.

At Bosco's house, a blackout occurs and Chema knocks Bosco out. In the ensuing struggle, Bosco fights back, intending to torture Angela, but she frees herself and shoots him dead. Angela visits Chema in hospital as the TV reports six bodies found at Bosco's home, and she hands Chema a book inviting coffee while declaring she will abandon her thesis; the announcer also warns that snuff-film footage will be shown on air.