Academic Ladyboy is overwhelmed by the dust stirred up by his city’s renewal projects and buys a vacuum cleaner to tidy his apartment. At night he hears the vacuum cough, and in the morning discovers it has expelled the dust it had cleaned. He calls a repairman who arrives almost instantly. The repairman, Krong, explains that the vacuum is physically fine but haunted by a ghost, and that many spirits haunted the factory that produced it. Smitten with the handsome Krong, the Academic Ladyboy lets him tell the tale of the haunted factory.
Suman, the heir of her late husband’s electronics factory, is troubled by the vengeful spirit of Tok, an employee who died of congenital heart disease on the job. Tok blames the factory for his death and frequently interrupts work by possessing machinery and angrily complaining. Tok is anchored to the physical world because someone close to him remembers his life. Tok’s spirit violates hygiene regulations, and Suman loses her license to operate the factory, forcing it to close.
March, the younger of Suman’s two sons, is mourning the recent loss of his wife Nat and their unborn child to a respiratory disease. While attending an investigation into Tok’s haunting of the factory, March sees Nat’s spirit walking into an inventory warehouse and follows her. Nat possesses a vacuum cleaner and seduces March. His family and religious authorities are disturbed to discover the young man engaging with a haunted appliance, and March is taken to a hospital.
Nat, still attached to the vacuum cleaner, travels to the hospital to visit March. On the way, she befriends Dr. Paul, the Prime Minister of Thailand, by cleaning the dust irritating his eyes. March now sees Nat as a human, and the two happily reunite, but Suman is again disturbed to find him making out with a vacuum. Nat stays with March through his stay at the hospital and the two discuss restarting their family by utilizing Nat’s frozen eggs.
Under pressure from her conservative in-laws, who never liked Nat, Suman confronts Nat with Buddhist monks who attempt to exorcise her. Nat is unfazed, and Suman responds by accusing her of stealing the vacuum cleaner, having it confiscated and disassembled by police. Dr. Paul intervenes, citing Nat as a “good ghost” who should be supported, dropping the charges and repairing the appliance. Frustrated, Suman resorts to having March committed to a psychiatric institution where he receives electroshock therapy designed to damage his memory; if he forgets Nat, her bond to the physical world will be severed and she will disappear.
Nat still manages to see March by entering his dreams, but as the therapy continues her form begins to fade. Nat enters Suman’s dream, where she vents her resentment of her in-laws, and pleads for her to stop the treatment. Having been financially backed into a corner due to the ongoing haunting and the factory’s closure, Suman strikes a deal with Nat.
The factory is “re-opened,” but it is a ruse to gather the employees and drug them to sleep so that Nat may systematically enter their dreams and deduce whose memories are allowing Tok to haunt the factory. Nat discovers Tok visiting his boyfriend Pin’s dreams, and Suman confronts Pin. She offers an ultimatum: receive electroshock therapy to forget Tok, or lose his job. This triggers a violent attack from Tok, possessing a refrigerator, and Nat intervenes to save Suman’s life. Pin is escorted away to receive the therapy, and having earned a reputation as a good ghost by saving Suman and the factory, Nat is now seen by everyone in her human form.
Dr. Paul summons Nat and March to his home, ostensibly to celebrate her, but ambushes them with a group of political and military figures who are haunted by ghosts stemming from violence they have perpetuated or benefited from. Some ghosts are fueled by the direct memories of loved ones, others by political dissidents familiar with history. Dr. Paul begs Nat for help and has rigged the electroshock therapy lab so that it can be used to systematically investigate dreams and “treat” those who remember ghosts. Nat refuses the unethical request, but when Dr. Paul offers to clear the bureaucratic red tape preventing her and March from using her frozen eggs, she agrees.
Nat’s project to mass-exorcise politically inconvenient ghosts is successful, but disgusts March and drives a wedge between the couple. March claims that Nat has changed so much he is forgetting who she used to be, and attempts to keep the memory of the eradicated ghosts alive by studying the history of political violence. On the day Nat receives her baby, she betrays March to Dr. Paul. However, before this information can be acted upon, March has a coughing fit that knocks over a bust of Nat commissioned by Dr. Paul; the bust falls on March and sends him to the hospital, the injury causing him to either die or forget Nat for good. Nat fades away, leaving a regretful Suman alone in the hospital with the baby.
Over the course of telling the story, Krong finds himself attracted to the Ladyboy’s growing distaste for Nat’s actions and her willingness to sacrifice her own kind for her personal gain. The two make love, and the Academic Ladyboy deduces that Krong is not actually the repairman but the ghost haunting his vacuum. Krong reveals that he was murdered by having his feet encased in concrete and being thrown into a lake; he is tied to the physical world by his daughter’s memories, which, thanks to Nat, are almost completely destroyed by Dr. Paul’s electroshock therapy. They make love again, and the Ladyboy vows to remember Krong as the ghost disappears.
The Ladyboy dives into the lake and retrieves the concrete block containing Krong’s feet, delivering them to Dr. Paul. Reconstituted by this act, Krong and a group of other vengeful ghosts invade Dr. Paul’s home with the help of his staff and kill him, his family and associates.
