The story, set in 1999, is told in flashback form: in June 1974 a federal justice agent, Benjamín Espósito, becomes spellbound by and subsequently entangled in the investigation of the crime of a young woman, brutally raped and murdered inside her house in a Buenos Aires neighbourhood. Her widowed husband, bank employee Ricardo Morales, is shocked by the news; Espósito vows to find the killer and bring him to justice. In his ordeal he is aided by his alcoholic assistent Pablo Sandoval and a newcomer, the upper class lawyer Irene Menéndez-Hastings, who takes over as department chief. Espósito's rivaling partner Romano pins the murder on two immigrant workers so as to get rid of the matter - an issue that enrages Espósito, who attacks Romano in a fury.
He finds a tip soon enough while looking over some old pictures provided by Morales: he comes across a dubious young man - identified as Isidoro Gómez - who looks at the victim in a suspicious way in several photos. Espósito investigates the whereabouts of Gómez, and determines that he is living and working in Buenos Aires, but fails to locate him.
Espósito and Sandoval break into Gómez's household in the city of Chivilcoy, hometown not only of Gómez, but also of Morales's ill-fated wife. During the illegal search, they (unwillingly) steal a set of letters written by the suspect to his mother. Back in Buenos Aires, the deed earns them trouble back at the courthouse, and neither make anything out the letters. In addition, Gómez remains at large due to a careless phone call made earlier by Morales, who desperately wanted to apprehend the killer of his wife. In the end, it is Sandoval who comes across a new lead: a fellow drinker in the bar identifies the various names mentioned in the letters as being those of various soccer players of Racing Club.
After identifying him as a Racing Club fan, Espósito and Sandoval attend a soccer match where Racing Club plays against Huracán in the hope of catching Gómez. With the assistance of police officer Molinari and his men, they spot him among the crowd, but a sudden goal provides the necessary disturbance for Gómez to slip away. A surreal pursuit ensues in which Gómez nearly vanishes, but he's ultimately knocked down in the middle of the pitch. Espósito and Irene Hastings subsequently stage a fake, largely illegal interrogation at the office. They succeed in bringing him to confess the murder by taunting him and hurting his macho pride.
Justice seems served; however, barely a year later, Gómez is released by a spiteful Romano, who is now working for a government agency. Amid increasing political violence, Gómez is set to work as a hitman for the far-right wing of the Peronist party. Espósito finds Sandoval shot dead upon arriving home - Sandoval used to pass the night at the house of his coworker, due to endless arguments with his wife about his drink problems. He presumes, and imagines, that Sandoval was killed by hitmen sent after himself, perhaps under Romano's orders, and that Sandoval posed as Espósito and sacrificed his life for his friend. A budding romance between Benjamín and Irene - the latter then recently married - is cut short by Sandoval's death and Espósito's ultimate decision to exile himself deep within the countryside, with the help of some of Irene's relatives. Here the movie makes a definite stop in 1999. After coming back from exile in 1985, Espósito returned to an uneventful career in Buenos Aires until his retirement. Haunted by the past, he's determined to write down his story in novel form. He presents the framework to Irene, still married and with children. She remains resentful and hardened from their sudden departure 24 years earlier, and for apparently never having had her feelings returned by him.
Espósito drives to Chivilcoy to meet Morales, the widower, who has taken to a quiet life and gradually let go of his obsession with the murder case. Espósito promises him that he will not rest until he can put the convict once again in jail. A hesitant Morales then confesses to having killed Gómez many years ago, having kidnapped him and shot him in the trunk of his car. A disturbed Espósito leaves, but upon thinking over certain facts, secretly returns to Morales's house. Sneaking inside, he is shocked to find that Morales has a makeshift cell in his home and that he has kept Gómez chained inside for over 24 years as punishment for his wife's death. He kept him alive by feeding him and tending to him, but not once in 24 years talking to him nor letting him out. Morales repeats what he had mantained in front of Espósito back to 1974: that, instead of a death sentence, he believes the boredom of a meaningless life in jail to be true justice.
Espósito leaves. He pays a visit to Sandoval's grave. Knowing that Gómez will never be a free man again, he finally comes to terms with his life. He visits Irene one more time, where he finally responds to her feelings. Their love rekindled, they smilingly shut themselves in her office.