A Mu [Li Wei] moves with his wife, Le Xiaomei [Daniella Wang], who is two months pregnant, to a secluded mountainside villa owned by his friend A Ming. The house is decorated with paintings showing two boys playing a string game, and there’s a locked room A Mu claims belongs to A Ming. Soon, strange, unsettling phenomena begin to haunt the couple: a red doll that seems to stalk Xiaomei, a music tape that plays a song from the string game, and, most haunting of all, a ghostly woman in a long white dress with hair that hides her face. The red doll is disposed of by A Mu at Xiaomei’s request, yet the paintings inexplicably reappear no matter how many times she tries to remove them. A Mu also keeps noticing a woman in a black robe watching him on his way to work, a presence that lingers in the corners of the daily routine.
One day, the couple visits the orphanage where A Mu grew up to raise funds. Xiaomei learns about a quiet, isolated orphan named Xiaoshan—A Mu’s contemporary who died when he was ten. After a series of threatening boxes are left at their doorstep, A Mu installs security cameras around the house. That night, Xiaomei reviews the footage and sees a cloaked figure leaving the premises. Spurred by fear, she breaks into A Ming’s room and discovers more paintings of the two boys and the disposed red doll. She is unnerved by the woman in white, bolts in panic, and in the struggle she tugs at the woman’s hair, slipping and falling down the stairs, which results in a miscarriage of their unborn child.
Back home after the hospital, Xiaomei presses A Mu to reveal the truth about Qingqing, a fellow orphan who had been close to him in childhood and who later left him for a rich man. Qingqing is later killed by A Ming, who justifies the act as retribution for her unfaithfulness. He shows Xiaomei the body the night before, despite her earlier claims about hair, and another box arrives warning not to comb hair at midnight—a superstition tied to Qingqing. When Xiaomei does comb at midnight, she summons the white-dressed woman, who reveals that A Ming does not exist.
From the orphanage files, Xiaomei learns that “A Ming” is actually Xiaoshan, the son of two imprisoned thieves whose only friend in the orphanage was A Mu. One day, the two boys escape from a locked room where they’d been imprisoned for robbery, slipping through the roof, but the dean prioritizes saving A Mu because he is her grandson born out of wedlock. She offers offerings for A Ming, yet dies of a heart attack, her face burned in the process. The woman in white later appears to Xiaomei as Yu Xiaohan, Qingqing’s younger half-sister. Xiaohan apologizes for the miscarriage and explains that she wants Mu Kainan, A Mu’s real name, to confess to Qingqing’s murder. She haunts him to coax the truth from him, declaring that “people would tell the truth if they are scared.” A Mu’s struggle becomes a fight between identities as he drifts between A Mu and A Ming. In A Ming’s persona, he overpowers Xiaomei, firmly establishing his role in Qingqing’s murder and his grandmother’s death, but his attempt to kill her is thwarted by memories of their relationship, and he ultimately decides to end his life to stop himself from harming Xiaomei further.
In the wake of these revelations, Xiaomei visits Yu Xiaohan in the hospital to tell her that A Mu left money for Qingqing and Xiaohan to cover their bills, and to convey that she is not alone anymore. She then returns to A Mu’s orphanage and encounters a new girl, Yangyang, carrying the red doll. Yangyang sings the string game song, and a hand reaches out to grab the doll just as the film cuts to black, leaving the fate of the characters and the truth hanging in the balance.
