|Directed by||Sergio Martino|
|Produced by||Luciano Martino|
|Music by||Luciano Michelini|
|Edited by||Eugenio Alabiso|
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Three army officials—Major Antonio Lorusso, Colonel Giulio Scanni and General Eugenio Stocchi—are murdered but made to look as if they committed suicide. When a wealthy master electrician named Salvatore Chiarotti is also found dead in his palatial countryside villa, Roman police inspector Giorgio Solmi, Lieutenant Luigi Caprara and Officer De Luca investigate. District Attorney Mannino arrives and he and Solmi learn that Chiarotti's last visitor was a young woman with black hair. Solmi's girlfriend Maria, a news reporter, arrives and tells him she has suspicions about the recent string of military suicides, but Solmi denies having any knowledge of it.
Solmi and Caprara visit and interrogate "Baronessa" Isidora Grimani, a retired "madam," claiming they found her number all over Chiarotti's agenda. They discover that she is running a brothel out of her estate and when Solmi demands information for her immunity, she tells them that Chiarotti's last visitor was an escort named Giuliana Raimondi, nicknamed "la Tunisina." Solmi and Caprara arrive at Raimondi's apartment to find she has slit her wrists. After transporting her to the hospital, Solmi and Mannino tell her she is the prime suspect in Chiarotti's murder. She first denies the charge but then, in a state of shock, claims responsibility.
Solmi meets with Maria and tells her that he is suspicious of Raimondi's admission of guilt. Additionally, he's discovered that Chiarotti was a private investigator, and he suspects a blackmail plot was at hand. Via a flashback, we see that Raimondi did not murder Chiarotti, and that she saw the true killer's face before she escaped. Back in the hospital, she describes the killer to Solmi.
Caprara and De Luca, who have been ordered to keep watch over Chiarotti's villa overnight, witness a man break Chiarotti's door seal with a key and try to steal tape recordings belonging to Chiarotti. The man is apprehended and taken into custody. Breaking the orders given by D.A. Mannino, Solmi listens to the recording, which contains a secret dialogue between General Stocchi and a mysterious lawyer named Rienzi. In the recording, Rienzi invites Stocchi to join him in a plot, to which Stocchi categorically refuses. The man in custody, Remo Ortolani, claims that he was working for the police's "Special Information Branch," which Solmi does not believe.
Solmi meets with Captain Sperli, who denies that Ortolani is an agent but expresses a desire to meet with him. Ortolani claims Chiarotti was blackmailing someone and he was aware of it, and that he wanted Chiarotti's tapes to acquire blackmail information on people. When Mannino attempts to listen to the stolen tape, he discovers it's been erased, which leads Solmi to suspect the presence of a traitor within the police department.
Solmi, Caprara and De Luca are surveilling the wife of oil baron Martinetti when Solmi confronts her as she enters her car and asks her for information on Chiarotti, saying he found her number in Chiarotti's address book. Martinetti says she contacted Chiarotti when she learned her husband was planning to leave her after she had a tryst, seeking blackmail information on him to protect herself. Solmi interrogates Martinetti on his private golf course and is told that Chiarotti sold blackmail tapes on his wife to him, which he purchased merely to sever ties with his wife for good.
Meanwhile, two armed assailants break into the hospital where Raimondi is staying and abduct her. Solmi then concludes that Chiarotti was murdered by a professional assassin and not for money. Mannino then places the blame for Raimondi's abduction on Solmi and his haphazard approach to surveillance and police procedure. Solmi requests that he be allowed to interrogate Ortolani but is told by Mannino that he has been set free due to lack of evidence. Solmi, Caprara and De Luca follow Ortolani to the local airport and Solmi confronts him in the restroom. As the trio transport Solmi to a secluded location for interrogation, an unknown assassin on a motorcycle murders Ortolani. After a lengthy pursuit, Solmi fires at the man, knocking him off a cliff, but he enters another car with two other men and manages to escape.
Raimondi's captors tell her that she must confess to killing Chiarotti or die, adding that she will only serve a short sentence and have money waiting for her in a Swiss bank account when she is released. Raimondi offers herself to one of the captors as a ploy to get him to untie her and manages to wrestle his gun from him and shoot him. She runs to a local gas station phone booth to contact Solmi, telling him that one of her captors, a man named Massù, killed Chiarotti. However, before Solmi can arrive to save her, she is killed by Massù. Arriving at the crime scene, Solmi and Caprara deduce that Massù's real identity is Giovanni Andreassi.
An informer gives the police a tip that Massù has just entered a boxing club, which Solmi and his men infiltrate. Massù tries to escape but is beaten up by Solmi and then arrested. After being tortured, Massù confesses that he made it appear that Raimondi killed Chiarotti and then murdered her so she couldn't talk, adding that Chiarotti was killed because he had collected embarrassing blackmail material on Martinetti and his wife. Martinetti strongly denies any connection to Massù and accuses Solmi of trying to defame him.
Mannino tells Solmi that Massù claims his confession was extorted and says they must confront Martinetti and Massù to discover who really killed Raimondi and Chiarotti. However, when they arrive at the prison where Massù is located, they find he has been killed in a prison riot. Solmi and Mannino review the prison's security camera footage and discover that an unidentified man who was not an inmate pushed Massù off the prison's roof, although the warden says this is impossible. Solmi and Mannino go to Martinetti's estate to confront him but are told he has flown to Kuwait.
Solmi is now completely convinced of the presence of a traitor in the police department. When Solmi has De Luca investigate a robbery at a local bowling alley, De Luca is murdered in a hit job intended to kill Solmi, when he takes Solmi's car which is filled with explosives.
In the news office, Maria receives photographs from Germany that show Stocchi's and Massù's killers appearing together. Solmi shares this information with Captain Sperli, who hesitantly reveals that he knows the identity of the killer: a German mercenary agent named Franz Schmidt, who's staying in a Roman hotel. Solmi and Sperli go to the hotel to pursue Schmidt, who is about to escape, as he's been tipped off that the police are arriving. Solmi manages to apprehend Schmidt, but before he gets a chance to interrogate him, Sperli shoots Schmidt and kills him, claiming he was protecting Solmi. Solmi orders Sperli not to move and gains access to Schmidt's room. Inside a suitcase, Solmi finds various papers, one of which includes a list of names, Rienzi's among them. Additionally, Solmi finds the geographical coordinates of a mountain camp.
Solmi and his men travel by helicopter to the camp, where a group of paramilitary forces are training. The mutinous rebels are encircled and overpowered by police forces, but someone manages to burn some secret documents before escaping in a patrol car. Solmi and Caprara pursue him, first by helicopter and then on foot, and the fugitive is soon forced to surrender. After seeing his face, the two policemen are stunned: the fugitive is Captain Sperli, and they deduce that Sperli and Rienzi are the same person.
On the way back to the police station, Sperli refuses to reveal the names of the other conspirators forming the junta. Sperli is suspended by the police department and is charged with murder, illegal dealing of military weapons and conpiracy to commit crimes. While transporting Sperli to the detention center to be interrogated by Mannino, Caprara reveals that he's devised a scheme for Sperli to escape, outing himself as the traitor policeman. However, when Sperli tries to escape, Caprara and other officers murder him on the street. Solmi leaves Maria to speak to Mannino but before he can reach his car he is killed by a drive-by assassin, as Maria looks on in horror from the nearby apartment building.
- Luc Merenda as Inspector Giorgio Solmi
- Mel Ferrer as District Attorney Michele Mannino
- Delia Boccardo as Maria
- Tomas Milian as Captain Mario Sperli
- Michele Gammino as Lt. Luigi Caprara
- Paola Tedesco as Giuliana Raimondi (AKA la Tunisina)
- Gianfranco Barra as Officer De Luca
- Carlo Alighiero as Remo Ortolani
- Antonio Casale as Giovanni Andreassi (AKA Massù)
- Gianni Di Benedetto as General Eugenio Stocchi
- Claudio Gora as Martinetti
- Clara Colosimo as "Baronessa" Isidora Grimani
- Arturo Dominici as Chief of Police
Silent Action was distributed theatrically in Italy by Medusa on April 5, 1975.
- Curti 2013, p. 151. sfn error: no target: CITEREFCurti2013 (help)
- Curti 2013, p. 149. sfn error: no target: CITEREFCurti2013 (help)
- Antonio Bruschini, Antonio Tentori. Città violente: il cinema poliziesco italiano. Tarab, 1998.
- Sindacato nazionale critici cinematografici italiani. Cine critica , Volume 12. SNCCI, 2007.