Takakura, 46, teaches criminal psychology at a university, and lives quietly with his wife Yasuko in Tokyo’s Suginami Ward. One day he receives a call from Nogami, a high-school friend who is now a police detective. Takakura is asked to assess the reliability of new testimony by Saki Honda in an eight-year-old case from Hino City, in which both of Honda’s parents and a sibling had disappeared. Three weeks later when Nogami comes to visit, he barely mentions the Hino case, and seems interested only in talking about Takakura’s next-door neighbor Akio Nishino, and the elderly mother and daughter, the Tanakas, who live across the street. Subsequently, the Tanaka house burns down, and the bodies of mother and daughter as well as that of Nogami are found in the charred ruins?leading to much speculation about what may have taken place.
Meanwhile, Yasuko has growing doubts about Nishino. The man’s middle-school-age daughter Mio has told her that he is not her father. Yasuko has not seen Nishino’s wife nor his high-school-age son in quite some time. Then Mio shows up at the Takakuras’ door in the middle of the night asking for help. Nishino comes after her and demands she be sent home, with such a ferocious aspect that he doesn’t even look himself. Yasuko calls the police, but when they arrive, they are taken in by the cooperative stance Nishino adopts and brush aside Mio’s insistence that he is not her father, and that her brother is missing. In the end, Mio is taken to a children’s welfare center, but then Nishino barges into the center wielding a knife, kills the director, and makes off with Mio. To add to these disturbing events, the body of Mio’s mother shows up in the Takakuras’ entrance hall missing a leg.
Nogami’s ex-wife Sonoko Kawai, a pianist, brings Takakura a letter Nogami had entrusted to her before his death; like Nogami, she has known Takakura since high school. The letter reveals that the man who has been calling himself Nishino is actually Nogami’s half-brother, Yoshio Yajima, who has been involved in numerous black deeds since he was in his teens; he has a diabolical ability to control others, and was also involved in the unsolved Hino case in some way. Soon the bodies of the real Nishino and Mio’s older brother are found.
Around the same time Yasuko receives a letter claiming that Takakura is having an affair with a female student enrolled in his seminar. Takakura suspects the letter was sent by a classmate named Ōwada, but Ōwada denies it; he claims he merely gave out seminar members’ contact information to his new neighbor, who works for a job information company. Recognizing Yajima’s MO, Takakura pays Ōwada’s neighbor a visit. When he realizes he’s been found out, Yajima stabs Ōwada to death and flees.
Ten years later, the whereabouts of both Yajima and Mio remain unknown. At a concert he attends, Takakura meets a pianist named Yū Kawai, who says she is Sonoko Kawai’s daughter?not her biological daughter, but adopted six years ago. Takakura thinks she bears a strong resemblance to the missing Mio. Then, when he sees Sonoko for the first time in ten years, she confesses to having killed Nogami. He had been repeatedly unfaithful to her during their marriage, and he had continued to demand money from her even after their divorce, further exacerbating her bitterness toward him. Needing to dispose of the body, she consulted Nogami’s half-brother, Yajima, who covered up Sonoko’s crime by having the body turn up in the charred ruins of the Tanakas’ home. Later Yajima used his knowledge of Sonoko’s secret to force her to take him in after he fled the children’s welfare center with Mio and needed a place to hide.
At her home, Sonoko shows Yajima’s mummified body to Takakura. She had poisoned Yajima with cyanide ten years before. But Takakura decides not to inform the police of Yajima’s murder: better to let them think the notorious murderer is still on the loose than to endanger Mio’s chance of overcoming her past tragedies and building a new life for herself as the pianist Yū Kawai.