Irish-American Terry Noonan returns to Hell's Kitchen in New York City after a long absence, where his unpredictable childhood friend Jackie Flannery is involved in an Irish crime organization run by older brother Frank. Terry rekindles an old relationship with Jackie's sister Kathleen.
Terry is actually an undercover cop, and confesses it to Kathleen. She is reluctant to have anything to do with him after being told by her brother Frank that Terry is now a member of his gang after killing two people, although Terry explains to Kathleen the killing was staged by his police boss Nick, with blanks used.
Jackie is drinking in a bar one night when three members of a rival Italian gang enter. Suspecting their involvement in the killing of his friend, Stevie, Jackie snaps and ends up killing all three for intruding on his gang's territory. Frank is summoned to a meeting with Italian Mafia boss Joe Borelli and is told he must kill his brother Jackie. Frank has told his men to lie in wait in case the meeting goes wrong, and manages to avert a shoot out by hugging the Italian leader outside the restaurant in full view of the gang, causing them to retreat.
Frank arranges for Jackie to collect $25,000 after lying to him that the Italians are actually supporting them and that this is their reward, telling him to go to Battery Park. Terry tags along as Jackie's secret backup, finding that the location has been changed to Pier 84. As they wait at Pier 84, Frank arrives with his enforcer Pat Nicholson just as Terry has stepped away to frantically phone his police handlers to inform them that they have been sent to the wrong location. Frank shoots Jackie in cold blood. The police finally arrive and Terry tells Nick that he is quitting as an undercover operative.
At Jackie's funeral, Terry reveals to Frank that he was at Pier 84, and also hands him his police badge. Hours later, while Kathleen is watching the St. Patrick's Day parade alone, Terry goes to the bar where Frank and his gang are. In a shootout, Frank and all of his men are killed. Having been shot three times, Terry slumps to the floor.
