Masafumi Kobayashi [Makoto Inamori] is a well-known paranormal researcher who has built a career around documenting supernatural activity across Japan, publishing books and producing documentaries. While working on a project titled The Curse, his life takes a dark turn: he disappears when his house burns down, and his wife, Keiko [Miyoko Hanai], is found dead among the ruins. The documentary itself begins to play, largely told through the footage captured by his longtime cameraman, Miyajima [Hisashi Miyajima].
A year and a half earlier, Kobayashi investigates a woman named Junko Ishii [Tomono Kuga] and her young son after a neighbor reports hearing the wail of crying babies coming from Ishii’s home. Ishii moves away, and when Kobayashi and Miyajima return to the former residence, they discover dead pigeons strewn about the property. An eerie car crash claims the life of Ishii’s neighbor and her daughter, deepening the sense that something ancient and malevolent is at work. Meanwhile, Kana Yano [Rio Kanno], a girl famed for her extraordinary psychic abilities on a television program, vanishes from public view. Her disappearance troubles Kobayashi, who learns that a man named Mitsuo Hori [Satoru Jitsunashi] had visited Kana; Hori describes her fate as the work of “ectoplasmic worms,” sending Kobayashi on a difficult trail toward obscure ritual practices.
Following this thread, Kobayashi and Miyajima shadow a man named Shin’ichi Osawa [Takashi Kakizawa], who has been seen bringing pigeons to a nearby apartment block and soon disappears himself. A film shoot at a shrine introduces another unsettling layer when the actress Marika Matsumoto [Marika Matsumoto] appears on screen, dreamily weaving yarn and wires into looping networks as she sleeps. A recording later reveals a voice whispering the demon’s name, Kagutaba. A local historian explains that Kagutaba is a demon from a long-ago myth, summoned by a village called Shimokage but imprisoned for disobedience. The villagers conducted an annual ritual to keep Kagutaba appeased until 1978, when the dam and the village’s demolition changed everything. The historian’s scroll traces Kagutaba’s origins to a disturbing ritual in which baby monkeys were fed to a medium; Ishii, it turns out, had attempted to replicate this by feeding fetuses stolen from a nursing school to Kana.
The investigation widens as Marika reveals that her neighbor Midori [Mana Okada] has committed suicide by hanging. Midori’s death, along with the other linked cases—including Osawa’s later demise—ties the events to a pattern of possession and ritualistic violence. Marika begins to show behavior consistent with a possession, and Kobayashi, Miyajima, and Hori head to the Shimokage dam to perform a ritual intended to appease Kagutaba, hoping to free Marika from the demon’s influence. The ritual is a tense ordeal: Marika’s crisis subsides briefly, but Hori’s agitation grows, and they discover the village’s dogs slaughtered near a secluded shrine in the woods. Kobayashi’s camera captures a haunting image of Kana standing near a torii, surrounded by writhing fetuses, before Marika’s possession suddenly lifts.
After delivering Marika and Hori to a hospital, Kobayashi and Miyajima break into Ishii’s current home, where they discover Ishii has hanged herself. Kana is dead, and Ishii’s young son—though initially believed to be Ishii’s child—appears not to be hers. Kobayashi makes the difficult decision to adopt the boy, trying to give him a safe future away from the malevolent forces surrounding the case. The historian’s scroll and Kobayashi’s growing concern push the investigation forward, even as Hori is placed in a mental institution; he later escapes and is found dead the following day.
With Kobayashi missing, a final, devastating twist unfolds when his video camera is recovered and examined. The tape reveals the house’s harrowing collapse: Hori storms the residence, exposing the boy as Kagutaba and bludgeoning him with a rock. The bloodied boy briefly takes on Kagutaba’s form, and a ghostly vision of Kana materializes in a corner. Hori departs with the boy, and Keiko becomes possessed once more, pouring gasoline on herself and igniting a fatal blaze. The house goes up in flames as Kobayashi struggles to rise, and the film ends with a stark note stating that Kobayashi remains missing, leaving the fate of everyone involved unresolved and haunting.
