Plot
Angela, a prostitute, has just had sex with a man now cowering under the bedsheets and angrily harassing her over not being fully satisfied due to shame. As Angela gets her things, she knocks over a chest filled with bladed weapons, scaring her and causing her to flee. Unwittingly taking a blue envelope with her, she finds it is full of newspaper clippings and memorabilia about the murders committed by an unidentified serial killer in Turin, nicknamed "The Dwarf Killer". The unseen killer from before calls Angela and threatens to kill her. With the train conductor no help, she calls her friend Amanda to retrieve the envelope from her at the station. The killer, who has followed Angela onto the train, chases her and cuts off her finger as she tries to escape before slashing her throat. After Angela does not meet her at the station, Amanda boards the train and finds Angela's gold pin and the envelope. She narrowly avoids getting stuck on the train and takes the envelope with her to her car. The killer follows her and stabs her to death in the driver's seat before taking the envelope back.
Detective Ulisse Moretti (Max von Sydow), the primary investigator of the original series of murders in 1983, has been keeping in close contact with Giacomo Gallo, the only survivor of the original spree, who saw his mother, Maria, stabbed to death with her own English horn. The first three killings in the spree became known as The Dwarf Murders because the main suspect, Vincenzo de Fabritiis, was a writer of crime fiction with dwarfism, but he died of natural causes and the case was considered closed. Moretti, since retired from the force, was never fully convinced of Fabrittis' guilt. Giacomo has taken years to cope with the trauma of his mother's murder, and gaps on his memory have haunted him ever since. Giacomo's girlfriend, Gloria, and his best friend Lorenzo Betti have just returned from their time studying abroad, arranged by Lorenzo's wealthy father.
Meanwhile, the killings continue to escalate. As nightclub dancer Mel is leaving work, the killer stalks and ambushes her. Dragging her to an indoor fountain during a lengthy struggle, he drowns Mel, then aggressively cuts her fingernails very short after she scratches him during the struggle. Moretti starts trying to solve the case, joined by Giacomo joins him. The differing modus operandi and much larger range in location of the recent murders compared to those in 1983 puzzle them both.
Cab driver Beppe finds an engraved pen belonging to the killer and blackmails him into arranging a meeting, where he is stabbed to death. Giacomo questions de Fabritiis' friend Leone, an alcoholic who also has dwarfism, who lives at the De Fabritiis home, where Vincent's mother Laura, still grieving the death and slander of her son, receives Moretti coldly.
The killer murders another woman, Dora, by slamming her face against a wall hard enough to knock her teeth out. While conversing with his pet parrot, Moretti goes over the murders and realizes the modus operandi and the animal-shaped paper tokens left at each murder scene match the violence in a disturbing nursery rhyme, "The Crazy Farmer". He theorizes the killer went mad after hallucinating the noises of the animals, and note that a swan is the final animal to die. Giacomo rushes to the ballet, fearing for the life of Gloria, who is performing the music from Swan Lake on her harp in a swan costume, but she is safe. The killer violently beheads Mara, the ballet dancer portraying Odette, instead.
Vincent's grave is opened and his casket discovered to be empty, with marks indicating the body was recently taken. Laura confesses to Moretti that she killed Vincent at his own request when the persecution of the public got to be too much to bear. Alone at home, she sees a shadowy figure she believes is Vincent before falling in terror over a banister to her death. At Moretti's home, just after he leaves an answering machine message to Giacomo about a break in the case, the same figure appears and recites the nursery rhyme, frightening Moretti into a fatal heart attack.
Giacomo and Gloria see Leone carrying a life-sized dwarf puppet and follow him to a house where they discover a workshop filled with puppets and Leone dead of a deep wound to his face. Betti's father appears and shoots Giacomo in his shoulder. After changing his mind about killing Giacomo, he apologizes to Lorenzo, who has arrived with Gloria, and shoots himself in the head. Giacomo then realizes the killer in both series of murders was the same, but was not a dwarf but a child in 1983, and is now an adult able to kill in a much wider area.
Giacomo confronts the killer, Lorenzo, realizing the hissing sound he heard during his mother Marta's murder was Lorenzo's asthma inhaler. Mr. Betti sent Lorenzo out of the country to stop him, then killed Leone when he was sure Lorenzo was killing again. Lorenzo smugly confesses he doesn't care his father's dead, and he was glad to return for the "game" of Giacomo trying to catch him. Lorenzo was driven mad by hearing animal noises, hallucinating them coming from women and killing them accordingly based on the rhyme. They never felt in danger in 1983 because of his young age, and when he went to Geneva and New York City, he slaughtered more people since the nursery rhyme was known internationally.
When Giacomo tries to grab a kitchen knife, Lorenzo pulls his own knife on Gloria and threatens to kill her if he doesn't leave. Giacomo complies just enough for Lorenzo to get to a window, where the detective on the case shoots Betti through the face, killing him instantly. The police raid the apartment while Giacomo consoles Gloria over the murders finally being over.
