Infiesto

Saioa is found walking along a rural road in Spain, dirty and injured, identified as the missing person who disappeared three months earlier. The country is entering a COVID-19 lockdown, restricting police resources as Inspector Samuel Garcia and Deputy Inspector Marta Castro begin the investigation. The discovery triggers the formal case and hospital intake.

Saioa's mother Julie is notified and arrives at the hospital where her daughter lies unconscious. The detectives note suspicion on Saioa's stepfather, who had left Julie the day before Saioa disappeared, but he has already been thoroughly investigated. The case expands to family dynamics while Saioa remains in care.

When Saioa regains consciousness, her therapist Paz restricts questioning due to her fragile state. Garcia and Castro continue the investigation, relying on other leads while Saioa's ability to speak remains limited in the hospital. The hospital becomes a place of guarded information and cautious progress.

A driver reports seeing a young woman at a rural intersection, prompting the detectives to investigate the area. They discover an old abandoned building nearby, where a young woman and a man flee the scene. Garcia catches the man, but they turn out to be pot-growing hippies and are released as irrelevant to the case.

A second woman reports a kidnapping attempt by a known felon called 'The Dog Killer' who lives near the intersection. The detectives search his property and find a makeshift bed inside a barn. The Dog Killer appears and claims the bed is used by his hunting cousin. They leave, but later grisly clues surface: sand used in wine making on Saioa and barrels in the barn suggest a link.

In the barn, authorities uncover a hidden room with evidence of captivity. The Dog Killer resists, and a roadblock leads to his capture, but he commits suicide, declaring 'It's only the beginning.'

The Dog Killer's cousin reveals that the killer hunts with a friend known as 'The Demon,' who has psychological issues. At the Demon's trailer, the detectives narrowly escape a booby-trap explosion and discover photographs of youths in white robes, hinting at a pattern of abductions every three months.

The Demon's brother is revealed to be Saioa's stepfather. The detectives learn of an abandoned building used by the Demon. A shootout at the building results in the Demon's capture, who again repeats 'it's only the beginning' and reveals membership in a cult led by the Prophet.

Saioa confirms a third person’s involvement in the cult. The Demon explains the cult's structure, worshiping the Celtic god Taranis and demanding human sacrifices every three months under the leadership of the Prophet.

Garcia, suspended for roughing up the Demon, notices a camp director wearing a Celtic straw doll and suspects him as the Prophet. He asks local detective Ramos to help identify the Prophet's old house. Meanwhile, Castro learns from Lidia Vega, a former cult member, that Ramos may be the Prophet.

Garcia confronts Ramos after suspecting him, and Ramos shoots Garcia before escaping. Castro and police arrive too late to stop him, but a search of a nearby abandoned mine is planned for later.

Castro descends into the mine, confronts Ramos, and kills him after a brief shootout. Before his death, the Prophet calls out that it is the beginning of the end of the world. The cult threat intensifies as the Prophet's warning lingers.

The film ends with Castro at the hospital alongside her recovering fiancé, while news reports rising COVID-19 cases unfold. The Prophet's warning and the cult's influence hint that the danger may persist beyond the final showdown.