Two years ago, six school friends — Ta, Kim, Por, Tair, Noot, and Ko — are pulled into a tangled web of secrets that centers on Ta’s family. Ta’s mother died when he was young, and his father has since married his former teacher, Panor. [Kim] is Ta’s ex and now dating [Por], the group’s self-identified nerd, while [Tair] is a tomboy who may share feelings with [Noot], a stylish singer, and [Ko] is their carefree friend. During their final high school year, [Panor] seduces [Por], a discovery hidden from the others. Por learns he isn’t the only man in her life: Panor is also married to Ta’s father and is having an affair with the sports coach, Coach O-Larn. Fueled by jealousy, Por convinces the friends to film Panor and the coach to “prove” the infidelity and broadcast the clip to the entire school. The coach uncovers the plan and derails the group, holding them at gunpoint while he sexually abuses them, with [Noot] as the most frequent target.
Seeking revenge, the students turn to a Shaman who agrees to curse the coach, though the shaman warns that black magic, once unleashed, will haunt them forever:
> Once you start, it will follow you till you die.
Days later, Por returns to the shaman and asks him to extend the curse to [Panor] as well. The coach dies in a gruesome display as numerous fish hooks emerge from his body, even as a healer tries to mend the wounds from a catfish fishing trip. Panor, embarrassed by the exposure, becomes a recluse, retreating to a riverside cottage.
In the present, the six friends reunite to visit the mausoleum of Ta’s father’s ashes and to pay respects to Panor. At Panor’s cottage, the group finds Miss Panor as a polite hostess, though Ta’s great-grandmother appears harmless but is secretly senile. As they stay, [Noot] experiences unsettling phenomena—doors moving by themselves, a white figure underwater, and Ta’s great-grandmother devouring a cat. Panor retreats to a hidden jungle hut where she keeps several corpses, each seated at a desk with a photo identifying the former students.
At dinner, the group discovers something horrific: the soup Panor has prepared contains dismembered body parts. Each student spits out a disturbing remnant — Ko a fingernail with a Doraemon drawing, Por a piece of tongue with a piercing, Kim an eye contact lens, and Tair an eyeball — revealing that the meat is, in fact, Noot. The truth hits hard: Noot was captured, tortured, killed, and cannibalized by Panor. They search the cottage for Panor and find a video camera recording Panor killing and cannibalizing the shaman, then advancing on whoever holds the camera with a tree branch.
Tair begins to hallucinate rotting corpses, and the friends flee to the outside, where a boat driver, seeing Panor, suffers a fatal fall into the river. Kim gazes into a vision of Panor and Ta’s father; in that vision, Panor tortures Ta’s father by ripping off his toenails to hobble him. When Panor leaves the room, Ta’s father shoots himself to end his suffering. Among the jars of pickled mangoes in the room, they later find Ta’s dead father preserved in one of them.
The group hurries to the dusty shrine to hide and pray. Tair is briefly possessed by Miss Panor, and Ko is overcome as dozens of geckos burst from his body, killing him. The youths decide to split up: Por and Ta go after Panor, while Kim and Tair stay outside the shrine. Kim follows into the dense jungle, and the two boys hear Kim fall. Ta finds Kim and pulls a piece of metal from her leg; Por, however, experiences eerie visions of Panor. As Ta searches for Por, Tair experiences further visions and ultimately dies by her own hand, gouging out her eyes.
Por locates Kim, who appears to him as Panor; he tries to shoot Kim, but Ta rescues her just in time. Por bolts into the jungle and discovers Panor chanting in her hut. Panor torments Por with a vision that hamstrings him and rips out his teeth; Por admits that a love spell he cast on Panor lured her into infidelity with the coach and into filming them, then punished her with a painful curse. The haze clears and he sees Kim and Ta; Kim is repulsed by Por’s confession, and she and Ta leave Por to face Panor alone.
Miss Panor arrives, binds Por, and drags him to her secret hut. She stabs him with a paralytic syringe, then pours boiling water down his throat and slowly scorches his skin with a blowtorch as police close in outside.
In the jungle, Ta carries Kim toward a small shrine when a call on Noot’s bag signals that she remains missing. Back in Panor’s hut, Panor performs CPR on a charred Por to keep him alive for torture, as a police raid erupts and Panor is fatally shot. Kim is rushed to the hospital, where Ta visits her. A TV news report reveals that the five students who visited Panor are dead, and Ta’s charred corpse is discovered.
Kim encounters Ta’s burned spirit as he explains that the video of Panor devouring the shaman was shot by Ta’s father, who threatened divorce after seeing the tape. Panor then tortured him, and he killed himself. Panor had locked Ta’s great-grandmother in a closet and was warned by her that breaking the spells—by killing the shaman and feasting on his flesh—could drive Panor insane; the coach had also cast a love spell on Panor. Panor herself is described as a victim of these spells, and her attempt to free herself led to the group’s torment. Ta’s vengeful spirit lured the friends into reliving his pain, and he sacrificed himself to save Kim because he still loves her.
A school flashback reveals Kim and another classmate once fancied Ta; Kim bets that if Ta cannot court her within a week, she will “offer” Ta to her. Kim meets the shaman again, who warns, “Once you start, it will follow you till you die,” and she receives a clay doll as a sign.
The film closes with Kim leaping from a hospital window to her death, clutching the clay doll given by the shaman, while Ta’s burned figure lies beside her, near the hospital bed, confessing his unwavering love.
