A Useful Ghost

A self-described academic ladyboy buys a vacuum cleaner to tidy his apartment. That night the vacuum coughs oddly, and in the morning he finds it has expelled the dust it had cleaned. A repairman named Krong arrives and explains the vacuum is haunted, foreshadowing that the factory's ghosts are involved.

Krong explains the vacuum is haunted and that many ghosts haunt the factory where it was made. He hints that Tok's spirit lingers by possessing machinery and disrupting work. The Ladyboy becomes intrigued and asks him to tell the full tale.

Suman, heir to the electronics factory, witnesses the vengeful ghost Tok blame the factory for his death and interrupt production by possessing machines. The ghost remains anchored because someone who remembers him still exists. The haunting disrupts operations at the factory.

March, grieving his wife Nat and unborn child, sees Nat's spirit in an inventory warehouse. Nat possesses a vacuum to seduce March, who is brought to hospital by the encounter. The haunting turns personal as memories collide with the present.

Nat travels to the hospital to visit March. She befriends Dr. Paul by cleaning dust from his eyes, and March is startled to see Nat as a human again. The two reconnect while Nat remains tethered to the vacuum in a strange, intimate bond.

Nat stays with March in the hospital and they discuss restarting their family by using Nat's frozen eggs. The idea blends longing with the strange reality of a ghostly pregnancy. The conversation deepens the overlap of life, memory, and haunting.

Under pressure from conservative in-laws, Buddhist monks attempt to exorcise Nat. Nat remains unfazed, and Suman accuses her of stealing the vacuum, which is confiscated by police. Dr. Paul intervenes, defending Nat as a good ghost, and the appliance is repaired.

Frustrated, Suman has March committed to a psychiatric institution where he undergoes electroshock therapy designed to damage his memory. The treatment aims to sever Nat's hold so she will disappear, but Nat can still enter his dreams. The situation grows more fragile as memories begin to blur.

Nat infiltrates March's dreams and then Suman's, seeking a way to stop the therapy. She negotiates with them inside the dreamscape, leveraging her influence to shape what remains of their memories. The therapy pressurizes the couple while Nat's presence lingers.

The factory is reopened as a ruse to drug employees so Nat can enter their dreams and deduce whose memories allow Tok to haunt the factory. Nat discovers Tok visiting Pin's dreams, and Suman confronts Pin with an ultimatum: undergo electroshock therapy to forget Tok or risk losing his job. A refrigerator is possessed by Tok, Nat intervenes to save Suman, and Nat is now seen by everyone in her human form as a good ghost.

Dr. Paul summons Nat and March to his home to celebrate Nat, but ambushes them with a group of ghosts who haunt political violence. He asks Nat for help mass-exorcising those ghosts and rigs the electroshock lab as a dream-treating tool. Nat refuses the unethical plan but agrees to clear bureaucratic red tape so she and March can use her frozen eggs.

Nat's project to mass-exorcise politically inconvenient ghosts is successful, but it disturbs March and strains their relationship. He studies the history of political violence to keep memory alive. On the day Nat gives birth, she shares a betrayal with Dr. Paul, but a coughing fit causes a bust to fall on March, sending him to the hospital and possibly erasing Nat from memory.

The Ladyboy grows attracted to Krong, who is revealed to be the ghost haunting the vacuum. Krong explains his murder—feet encased in concrete and thrown into a lake—and that his connection to the living is kept by his daughter's memories, which Nat nearly destroys. They share a kiss, and the Ladyboy vows to remember Krong as the ghost fades away.

The Ladyboy dives into the lake to retrieve Krong's concrete block feet and returns them to Dr. Paul, reconstituting Krong. Krong and a group of vengeful ghosts invade Dr. Paul's home and kill him, his family and associates in a final act of retribution.