A retired detective with insomnia is called upon to solve a series of murders. His partner is a fresh faced rookie who has the aid of the latest technological equipment to help solve the crimes. Will they catch the killer?
Turin, 1983. Commissioner Moretti tells to a boy: "I'll catch the killer of your mother, I'll catch him for all my life". Same town, 17 years later. The murderer is back (he is not dead, as people thought for a long time), he attacks two girls and a long strip of blood begins. The boy now is an adult and when he meets the old Moretti they decide to close the case forever. To do it they must solve the puzzles of the killer, nicknamed The Dwarf: where the corpses are found, there is always a piece of paper with the form of an animal. And in a mysterious house is hidden a poem titled "The animal farm" but it's not the Orwell novel... it's a clue.
An elderly and retired police detective and a young amateur sleuth team up to find a serial killer whom has resumed a killing spree in Turin, Italy after a 17-year hiatus.
- In Turin, Italy, 1983, Detective Ulysses Moretti investigates a murder scene and tells a young boy named Giacomo that he will find his mother's killer, even if it takes the rest of his life.
Seventeen years later.
Angela, a Rome prostitute, refuses to let a man do "disgusting things" to her and he gives her money and tells her to leave. After cleaning up in the bathroom, Angela hears the unseen man mumble in his sleep about killing "lots of people". In a panic, Angela runs, knocks over a table (that has several knifes on it), gathers her things and leaves. On a train heading back to Turin, she realizes that she inadvertently picked up a blue-colored file which is full of articles, photos of dead people, and a copy of 'The Death Farm' poem by John McKenzie. After recalling a past murder case which involved "the dwarf killer" Angela calls her friend Amanda on her cell phone and tells her about the file and says to meet her at the train station. But a minute later, the killer calls Angela, calling her a thief and threatening to killer her for he is on the train. Angela runs down the train corridor until she finds a conductor and asks him to stay with her until reaching her destination. She returns to the cabin to get her things, hears a noise, and runs. She runs into the conductor who is knocked out cold. She tries to hide in another vacant cabin, but the unseen killer catches her, and stabs her to death.
At the train station, Amanda arrives and looks around the train and finds the blue file. She goes back to her car in the parking lot, but the killer is there waiting for her, and stabs her in the neck, killing her. Beppe, the car lot attendant, finds a gold pen on the ground as he sees the killer get out of the car with his blue file. A little later, Inspector Manni and other cops arrive on the scene where they investigate both killings, and the conductor tells Manni about Angela mentioning the killer dwarf. The next morning, Manni goes to visit Moretti, who was in charge of the case back in 1983, and he talks about "loose ends" of the dwarf suspect being found shot in the head from a suspected suicide before he could be apprehended for the killings. Moretti, already in his 70s and long retired from the police force, tells Manni that his memory is not what it used to be.
Across town, Mel, a young woman who dances in a skin-tight "kitty" costume at a local nightclub, prepares to leave when she goes to her dressing room when the lights go out. She hears the sounds of a cat howling and is scared by Marco, a bouncer who tells her that there is a short circuit in the fuse box. After he leaves, Mel goes up a dark staircase to the exit where at the top she sees a figure wearing a yellow jacket. She thinks it's Marco until the figure turns around, wearing a hood. The killer grabs her, but Mel puts up a fight, scratching the killer's neck, but gets punched out cold. The killer drags her to a tub of water in the maintenance room, where he drowns her, and then cuts off her fingernails as not to leave skin DNA evidence behind. Manni and the police arrive on the scene later and discover a cutout of a cat near Mel's dead body. Manni informs Moretti of this latest murder, and the elderly detective tells Manni that the killer used to leave cutouts of animals in the "dwarf killer" case 17 years earlier.
Meanwhile in Rome, the young boy Giacomo, whom Moretti vowed to help find his mother's killer, is working as a busboy in a local Chinese restaurant when he gets a phone call from Lorenzo, an old childhood friend whom he hasn't seen in 10 years, who urges him to come back to Turin to help out with family problems of his. Giacomo arrives and Lorenzo lets him stay at his family house. Giacomo then goes to the police station where Moretti is there and hears him talking to Manni and remembers when Giacomo says his mothers name: Maria Gallo. Reunited, Giacomo and Moretti talk about what transpired during the 17 years when they first met, and they go to the scene of Maria's murder. Giacomo tells Moretti that he could not see the killers face, but he remembers a "whistling" or "hissing" sound afterwards.
That evening, Giacomo eats dinner with Lorenzo's family where his father, Mr. Betti cannot find his gold pen. Later, Lorenzo talks to Giacomo about his stern father wanting him to be an athlete and sent him abroad to various schools, while Giacomo talks about fighting his abusive father. Giacomo goes to see his old school friend Gloria play a harp for a opera house crowd. Afterwords, he, Glroia, Lorenzo and his girlfriend, and Fausto, Gloria's boyfriend, go out to a local nightclub to party. Fausto talks about the latest killings and think that the dwarf killer, Vincenzo de Fabritiis (aka: John McKenzie) and says that he does not think that the man is dead. The next day, Giacomo and Moretti go to the Villa de Fabrittis and Giacomo thinks he sees Vincenzo in the window. They meet a derelict, named Leone, who recites a familiar verse of the poem to Moretti, but says that he cannot remember any more.
Meanwhile, Beppe meets with the unseen killer about offering to give his gold pen back, and wants blackmail money to keep his mouth shut. The killer gives Beppe a wad of cash, and Beppe gives the killer back his pen. But then the killer writes something on Beppe's hand and suddenly shoves the pen into Beppe's head many times. Giacomo and Moretti arrive on the scene a few minutes later and notice the words I am a bad boy written on Beppes hand. They call the police, where Manni is upset that the two of them are trying to investigate the murders on their own and tells them to back off and let the police do their own work.
Giacomo and Lorenzo meets their friends at a bar. When they sit back down at their table, Lorenzo accidentally drinks from Giacomo's glass of beer, notes a funny taste and collapses. In the hospital, Giacomo says that the poison was meant for him, and Lorenzo's father, Mr. Betti, arrives and tells Giacomo to stay away from his son. Giacomo leaves, and Gloria runs off after him. Moretti, up late at night because of his insomnia, recalls another verse of the rhyme and believes that the killer is murdering to the nursery rhyme.
The following day, Dora, a waitress in a local fast-food restaurant whom her friends call her "little rabbit" because of her large front teeth, is working when the unseen killer sees her. That evening, Dora leaves work, gets on a train and walks outside to her apartment building. She just lets herself in the door when the killer runs up and attacks her. Dora puts up a fight by biting the killer's arm with her large front bunny teeth. But she gets overpowered and the killer slams her face into a wall, knocking out her front bunny teeth. The killer leaves a cutout of a rabbit by her dead body.
Moretti tells Giacomo of a manuscript Vincenzo had said was stolen, believing the killer was using it to kill. At the house, they meet Vincenzo's elderly mother, Laura and they ask her about his books. Gloria calls Giacomo and tells him about Swan Lake which he is about to perform that night. Moretti finds a childrens book, 'Animal Farm', with pages missing., and he thinks that Vincenzo had hidden the pages of the original text from the killer. He looks at an old copy of George Orwell's book, 'Animal Farm', and finds the missing pages, which contain the nursery rhyme. The last verse, following the death of a cat, and a rabbit, mentions killing a swan. Giacomo quickly drives to the Swan Lake performance and runs backstage, and finds Gloria alive and well. But a minute later, they find Mara, the ballet dancer who danced to Gloria's harp music, dead and beheaded in her dressing room.
At the local cemetery, Vincenzo's coffin is exhumed, but the corpse is gone. Laura goes to see Moretti at his house and says that she does not want the rumors to start again. She says that she knows her son is dead because, not wanting him to go to prison for murders that he did not commit, shot and killed him herself and made it look like a suicide. Moretti tells her that the gun used was never found, and Laura tells him that she has it. Laura goes back to the estate to retrieve the pistol from a hidden place. She sees a short figure approaching her in the dark, backs up, and falls off a railing to her death.
That evening, Moretti phones Giacomo and leaves a message on Gloria's answering machine. Just then, the phone lines goes dead, then the light go off. Moretti sees a tiny person walking out of the darkness. Moretti takes out a pistol from his desk drawer and fires repeatedly, but the figure keeps on approaching. Suddenly, Moretti grabs his chest, and falls to the floor dead. The next morning, after spending a passionate night with Gloria, Giacomo finally hears the message on Gloria's machine where Moretti talks about the murders being in a small neighborhood in 1983, and they are now happening all over the city in 2000, plus Moretti mentions a "discrepancy" in his mothers killing and the handwriting on Beppes hand. Manni then calls and tells Giacomo that Moretti had died from a heart attack.
Giacomo and Gloria get into her car and give the bum, Leone, a lift. He is dropped off and Giacomo gets out to give him a bottle of wine he left in the back seat. At the shed of the Vincenzo estate, he sees Leone with a puppet dwarf and he runs back to the car to tell Gloria. Giacomo and Gloria follow Leone to an apartment building, and Gloria goes to her car to call the police while Giacomo climbs a fence and walks inside. Upstairs, he finds Leone dead from a shot to the head and Mr. Betti appears in the room and shoots Giacomo in his shoulder. Lorenzo and Gloria rush in and pound and yell at the front door, and Mr. Betti suddenly shoots himself. Lorenzo and Gloria run in and Lorenzo is clearly distraught to see his father dead, in which he begins hyperventilating and uses his asthma inhaler.
When Lorenzo walks out of the room to call the police, Giacomo tells Gloria what Moretti had learned. The killings in 1983 were in a small area because the killer was a child back then, and now in 2000, they are all over the city because the killer, now an adult, can go anywhere he wants. Additionally, a child would take the rhyme literally, not realizing "instrument" referred to a weapon. Just then Lorenzo returns to the room and, in a sneering, wild-eye tone, congratulates Giacomo of figuring it all out. Giacomo takes Lorenzo's inhaler away from him and says that was the hissing sound he heard, and knows that Mr. Betti knew about his sons killings and sent him away to prevent him from killing again. Lorenzo says that he was doing fine on his own and called Giacomo back to Turin because he wanted to play a game between the two of them so Lorenzo could get caught, and he even deliberately took a sip from Giacomo's poisoned beer that night to divert any suspicion away from him. Leone was Lorenzo's co-conspirator who used the dwarf puppet to make it look that a dwarf was doing all the killings of the present. Lorenzo suddenly grabs a knife and holds it against Gloria's throat, threatening to kill her of Giacomo approaches him any further. Giacomo asks Lorenzo why he did not kill anyone for this long and why did he start again after 17 years. Lorenzo replies: "who said I stopped?" He tells of other places in Switzerland, Paris, Germany, England, Spain and the USA where there have been dozens of unsolved killings over the past 17 years and replies "they know the nursery rhyme there too!" Backing up towards a window, Lorenzo threatens to make Giacomo watch, when Manni and the police arrive and seeing Lorenzo in the window, open fire several times, literally blowing Lorenzo's face off. Giacomo and Gloria embrace as the cops run inside the apartment and huddle them out to safety.