On the streets of Brooklyn, New York, police detective Gino Felino and his partner, Bobby Lupo, stake out prostitutes, but when they see a pimp beating a young lady, they run to her rescue with a team of undercover officers. Elsewhere in Brooklyn, mobster Richie Madano promises to give his gang the cash in his vault if they follow his orders. Later, Richie shoots Lupo dead in front of his wife, Laurie, and their two children and leaves a Polaroid photograph on the policeman’s chest. At his apartment, Gino prepares for a game of catch with his son, Tony, when he receives a phone call from police headquarters, informing him of Lupo’s killing. Gino calls his estranged wife, Vicky, and arranges for her to take care of Tony. She meets Gino at the crime scene and comforts Laurie while police captain Ronny Donziger tells Gino witnesses identified Richie as the killer. Donziger says Richie reportedly left an object on Lupo’s body, but it was not discovered. Despite Vicky’s protests, Gino decides to avenge the death of his best friend and asks Donziger for a rifle. Before leaving, Gino tells Vicky that she does not understand the code of revenge in their neighborhood and promises to be at their divorce hearing. Meanwhile, a member of the Italian mafia and Gino’s childhood friend, Frankie, learns about the murder and orders his men to procure Richie before the police track him down. When Gino meets with mob boss Don Vittorio, he learns that Richie is not a member of the Vittorio’s clan. Although Vittorio argues that the mafia should execute Richie, Gino is undeterred from his mission. Reporting back to Donziger, Gino sees the driver in front of him dump a puppy onto the street in a garbage bag and nearly hits it with his car. Holding the dog in his arms, Gino prays that he will one day make the offender pay for his crime. Gino drives through crime-ridden Brooklyn with the puppy in search of Richie and enlists the aid of Picalino, a boy who sells soda on a street corner. Eventually, Gino finds Richie recruiting more supporters, but the gangster and his henchmen climb into their car and speed away. Although Gino gives chase, his car is blocked by a truck and Richie and his men stop at a butcher shop for ammunition. As they run away, they order the merchants to attack Gino, but the policeman overcomes them. That night, Gino buys food for his puppy and runs into Frankie, who claims there is little difference between police officers and gangsters. Frankie and his men then go to a bar owned by Richie’s brother, Vinnie, and threaten him to obtain information about the murder, but Vinnie claims ignorance. Meanwhile, Gino visits Richie’s parents, and Mrs. Madano begs him not to kill their son. When Gino asks where Richie is, Mr. Madano says he knows nothing and Gino warns that Richie will not survive unless he turns himself in. Elsewhere, Richie and his gang barge into the home of a former prostitute, Rica, and her sister Elena, looking for sex. Although Rica objects, she is intimidated by Richie and follows him into the bedroom. Back at Vinnie’s bar, Gino tries to threaten patrons for information about Richie, but nobody responds because he is a police officer. After knocking out the bartender, Gino shoots his gun into the ceiling and orders the bar patrons to gather together. When Vinnie questions Gino’s resolve, Gino drops the cartridge from his gun and challenges the patrons to come after him for the trophy of his police badge. He beats his attackers, breaks Vinnie’s nose and announces he will return. Meanwhile, the police raid Vittorio’s strip clubs in search of Richie and the mob boss becomes increasingly eager to capture him. At a restaurant, Vittorio appeals to Gino, but Gino vows that he is not sympathetic to the mafia. Elsewhere, at an illicit auto mechanic shop, Richie obtains a police radio while Gino visits a nightclub owned by Richie’s sister, Patti. As Gino waits for Patti, the waitress leaves a napkin on the table with the name “Roxanne” written on it. Although Gino threatens Patti with prison time for her unlicensed gun, she denies having information about Lupo’s murder, and he arrests her. Back at the police station, Gino breaks the lock on Lupo’s desk to find cocaine and pornographic Polaroid photographs of Lupo and a lover. When Mr. Madano comes to the police station, he confesses to Gino that his son is a menace and he wants the suffering to end. Later, Gino interrogates Patti about Lupo’s pictures, but, fearing for her life, Patti refuses and Gino arranges for her and Mr. Madano to spend the night in police custody. Later, Gino receives a radio dispatch summoning him home as Richie listens from his car. When Gino returns to his apartment and tells Vicky about his childhood, they kiss and agree to reconcile, but Richie’s henchmen arrive and a gunfight ensues. After killing the attackers, Gino leaves his family under police protection and returns to Patti’s club. When the waitress identifies Roxanne from Lupo’s Polaroid, Gino finds her address in Patti’s Rolodex. Meanwhile, Richie arrives at Vinnie’s bar. After beating his brother for failing to fend off investigators, Richie and his henchmen kill a gang of Vittorio’s men. At Roxanne’s apartment, Gino finds two Polaroids on her murdered body. When Donziger arrives, Gino shows him the photographs and reports that Lupo was having an affair with both Terry, the waitress, and Roxanne. Gino visits Laurie and finds the Polaroid that Richie left on Lupo’s body in her purse. Gino concludes that Laurie sent the photograph to Richie in a fit of jealousy, but she insists that she did not mean to have him killed. Back in his car, Gino receives a call from Picalino, who reports that Richie is at Rica’s apartment. Sneaking inside, Gino finds Richie’s men partying with drugs and women. After Gino shoots several henchmen dead and blows the leg off of another, he looks for Richie in Rica’s bedroom. She indicates that Richie is hiding in the bathroom and the men exchange gunfire through a thin wall. Richie steps forward with his gun to his head, pulling the trigger to prove he is out of ammunition, and challenges Gino to arrest him. Instead, Gino drops the cartridge from his own gun. The men fight, but Richie is no match for Gino and after Richie goes after him with a corkscrew, Gino uses it to pierce his adversary’s forehead. When Frankie arrives, Gino takes the mobster’s gun and fires twice into Richie’s dead body. He tells Frankie to take credit for the hit. Sometime later, Gino and Vicky walk on the boardwalk with their puppy and Gino sees the man who threw the dog onto the street. Gino kicks the offender in the testicles and, as he falls to the ground, the puppy urinates on his face and the couple walks away arm in arm.