In 1983, a film titled
Antrum was submitted to various film festivals, but none accepted it. After each rejection, the festival directors die under suspicious circumstances. In 1988, the film was shown at a theater in
Budapest. During the screening, a fire - started by audience members - burned the theater to the ground. In 1993, the film was screened in a California theater, where a concession stand worker dosed the popcorn with
LSD. The combination of the drug and the film's imagery caused a
riot in which a pregnant woman died. Following this screening, all copies of the film apparently vanished, and it earned a reputation as being cursed. In 2018, a copy of
Antrum surfaces, prompting a documentary crew to make a film about its history and impact. Scientists and experts who examine the
35 mm reel determine that the film utilizes disorienting sounds and subliminal imagery. The crew also finds disjointed black-and-white snippets that appear to be a
snuff film spliced into the reel. The documentary pauses to present
Antrum in its entirety for the first time in 25 years.
Antrum concerns siblings Oralee and Nathan, whose pet dog Maxine was recently euthanized. Asked whether Maxine went to Heaven, their mother teases Nathan, saying that Maxine has gone to Hell for being a bad dog, disturbing him. After a nightmare of Maxine attacking him unprovoked, a traumatized Nathan begins experiencing disturbing dreams and visions of demons. To ease his mind, Oralee stages a ritual to allow Nathan to save Maxine's soul. She shows him a sketchbook filled with arcane sketches and drawings - presented as a
grimoire obtained from a (non-existent) classmate named Ike. She takes Nathan to a nearby forest, and guides him through a series of rituals and "rites," intending for him to discover Maxine's collar - a "sign" they have saved her soul. As the day progresses, however, Oralee is disturbed to find that her "spells" are apparently affecting the real world, conjuring actual infernal figures. Additionally, the pair accidentally interrupt a man attempting
seppuku, and obliviously pass by the rotting corpse of a suicide near their campsite. During their first night in the woods, Nathan sees a boat carrying a nude woman being rowed by a figure resembling
Charon. He also hears a rattling chain that he attributes to
Cerberus. The next day, Nathan and Oralee stumble upon a pair of
cannibals, who cook people alive inside an iron statue of
Baphomet, including the man whose suicide attempt they earlier interrupted. When the cannibals notice them, the two abandon camp and row downriver in the boat Nathan saw the night before, but they both fall into the water. The pair makes it to shore, only to realize they have circled back to their camp. As they hide for the night, Oralee confesses the ruse to Nathan. However, Nathan claims to have met Ike, who told him not to trust her. The next morning, the cannibals capture them. They prepare to cook Nathan, but Oralee escapes her cage and frees him. As Nathan flees, Oralee obtains a gun and fatally shoots the cannibals. In the woods, Nathan stumbles across a dog caught in a bear trap. Nathan frees the animal, taking it as a sign he has freed Maxine from Hell. A "The End" title card appears onscreen. However, the film abruptly resumes, following Oralee as she runs through the woods, pursued by demons, and experiencing violent hallucinations. She gets back to their camp and hides in the tent, aiming her gun at the entrance. As Nathan approaches, a panicked Oralee prepares to fire, and the film ends. The documentary resumes shortly after this, with scholars observing a rune seen throughout the film, which belongs to a demon named
Astaroth. Examples of the rune appearing subliminally throughout the film are shown as historians recount tragedies attributed to the demon throughout history. ==Cast==