Ilija Čvorović, Danilo 'Bata' Stojković, a former Stalinist who spent years in a prison on Goli otok, is contacted by the police to answer routine questions about his sub-tenant Petar Markov Jakovljević, Borivoje Todorović, a businessman who spent twenty years living in Paris and has returned to Belgrade to open a tailor shop. After a brief questioning, Ilija is free to go, but the encounter leaves him shaken and convinced that Petar might be a spy, a seed of doubt that soon grows into a full-blown obsession.
As time passes, Ilija becomes convinced that Petar, a cosmopolitan figure from a capitalist milieu, represents a grave threat to national security and the socialist system, and he begins spying on him with increasing fervor. This fear spills over into his family life: Ilija’s wife Danica Čvorović, Mira Banjac, is more worried about the future of their daughter Sonja Čvorović, Sonja Savić, a recent dental school graduate who struggles to find a job in a tense economy.
After a bout of surveillance, Ilija phones inspector Dražić, Milan Štrljić, claiming that Petar has been meeting with “suspicious people” (actually Petar’s intellectual friends), but the inspector does not take him seriously. Undeterred, Ilija escalates his own operation, turning his house into a fortress of suspicion. He acquires a guard dog, arms himself with munition, and even enlists the help of his brother Đura Čvorović, Zvonko Lepetić, who also grows convinced that Petar is a foreign agent.
One evening, Ilija is suddenly hit by a car, an incident he interprets as an assassination attempt, a frightening omen that reinforces his paranoia. Danica gradually begins to share some of her husband’s fears, while Sonja remains skeptical, viewing her father’s behavior as a dangerous slide into madness. Đura intensifies the crackdown by capturing several of Petar’s friends, locking them in his basement, beating them, and forcing them to “reveal their terrorist plans.”
Petar himself arrives at Ilija’s house, intending to say goodbye as he prepares to travel to New York, and he asks Danica why Ilija and Đura have been tailing him, revealing that he was aware of their “surveillance operation.” A confrontation erupts as Ilija and Đura storm into the house, drag Petar to a chair, and begin a brutal interrogation to extract a confession. Petar continues to insist that he is not a spy, but the brothers refuse to believe him. Đura steps out briefly to fetch one of Petar’s friends who supposedly admitted everything, while Ilija presses on with the interrogation.
The tension peaks when Ilija becomes overwhelmed and suffers a heart attack. Petar, still handcuffed to the chair, manages to phone for an ambulance and even tries to reach his plane as the clock ticks down. In a final, desperate move, Ilija phones Đura’s house and orders his wife to relay instructions to “block the airport.” Gritty and exhausting, Ilija crawls out of the house, dragging himself after Petar, with his loyal dog trailing behind, driven by a fevered mix of love, fear, and unresolved trauma.
