Maverick New York police detective Eddie Ryan has little regard for professional ethical behavior, regularly taunting, bullying and humiliating suspects in order to solve crimes. During a massive police raid at the club Carorrojeno's, Eddie's racial epithets terrorize Chico, one of Puerto Rican smuggler Sweet William's men. With Eddie close behind him, Chico scrambles to the roof and falls to his death in front of dozens of witnesses. Under pressure from the press and the Puerto Rican community, the police commissioner suspends Eddie until a departmental trial. Taking a job as a bartender, the divorced Eddie meets coat check girl Maureen, with whom he begins a casual affair. Five weeks after Eddie’s suspension, his partner of three years, Puerto Rican Gigi Caputo, is murdered in Brooklyn after hinting to Eddie that he is working on a big case. Determined to avenge Gigi’s death, Eddie conducts a ruthless investigation of his own, which leads him to suspect Gigi’s new partner, Frankie Diaz. At Gigi’s wake, Eddie learns from his embittered widow Marie that Gigi spent his last few weeks with prostitute Rita Garcia. Shocked by the infidelity, Eddie then brashly insists that the commissioner reinstate him to solve the murder and refuses to answer reporter Pete’s questions, saying that he actually never truly knew Gigi. After being nearly run over by unknown assailants, Eddie tracks down Rita to a shabby Long Island hotel, where the drug-addled prostitute mumbles that William is running guns to Puerto Rico. Moments later in the parking lot, Eddie hears gunshots and returns to the room to find Rita dead. As he attempts to report the murder to his former superior, Scanlon, shots tear into the phone booth. Back at her apartment, Maureen begs Eddie to give up the vendetta. Eddie ignores her pleas, asserting that he is committed to finding Gig's murderer. Despite departmental warnings to stay away from Eddie, Scanlon secretly meets with him to discuss the case, but has no information on William's smuggling and warns Eddie that the police believe he shot Rita. Suspecting Gigi knew of William’s plan to sell stolen guns to radicals mounting a revolution in Puerto Rico, Eddie attends Rita’s wake to meet her brother Ruben, the radicals' leader. Eddie tries to convince Ruben that William is responsible for his sister's murder, but Ruben insists that poverty and racism are to blame. Incited by rumors that Eddie is responsible for Rita’s death, the radicals confront him on the street. After Eddie narrowly escapes by commandeering a public bus, the radicals steal several cars and chase the bus as it careens wildly down the street, causing several collisions and finally crashing into a storefront window. The group then beat Eddie mercilessly until the police arrive. Afterward, Scanlon visits the recovering Eddie in the hospital to warn him that the district attorney now suspects that both Gigi and Eddie were involved in smuggling, and suggests that he lay low. Driving with Eddie to his upstate cabin, Maureen hopes that Eddie will finally demonstrate his affection for her, but the policeman, whose right hand is in a cast as a result of the accident, spends his time obsessively target shooting with his left hand and then leaves for the city, refusing any declaration of love. While attending a freedom rally where Ruben preaches violence in order to end United States imperialism in Puerto Rico, Eddie is forcefully taken to William's sumptuous apartment hidden inside a meat-packing plant, where the Harvard-educated criminal tells him Gigi was murdered for trying to blackmail William for gun running. Fearing he is next, Eddie jumps through a window into the Hudson River below, where a tugboat operator rescues him. Days later, William meets with the gun buyer and makes plans to meet at a harbor dock for the final payment and to load the guns bound for Puerto Rico. William frankly tells Ruben that after growing up in poverty, his only motive now is profit, adding that political dreamers like Ruben usually die. Meanwhile, Eddie, unable to drive since the injury, forces Maureen to tail Diaz, but she is shot and killed in the chase. Cradling her lifeless body, Eddie finally is able to tell her he loves her. With nothing left to lose, Eddie continues his dogged pursuit to Diaz’ apartmentand learns, by holding the policeman and his wife at gunpoint, that Ruben ordered his sister’s execution to save himself. Under Eddie’s brutal interrogation, Diaz adds that the guns are to be shipped from the Brooklyn Navy Yard. Calling Scanlon for police backup, Eddie proceeds to the shipyard, knocks out a guard with his cast and shoots into the crowd of radicals who jump onto the ship. Meanwhile, William kills Ruben but fails to catch the ship, which is pulling away as the police sirens approach. Now alone, William flees onto a crane scaffolding with Eddie in pursuit. After Scanlon orders his men to hold fire, numerous police watch as a cornered William throws money at Eddie, pronouncing that it is easy to buy a cop. Unable to control his contempt, Eddie shoots William, who falls to his death. As a dredge works till dawn to recover the body, Eddie finally walks away from the crime.