After New York City firefighter Terry Lynch is unable to receive any compensation for an injury incurred during the off-duty rescue of a young girl, he grows suicidal. Furious, his brother Jimmy attempts to have Mayor Tyler intervene, but the corrupt politician instead denounces Terry as a drunk. Determined to get justice, Jimmy begins a graffiti campaign of embarrassing slogans mocking the mayor, which soon captivates the city.

When his partner is killed, tough Irish detective Eddie Ryan vows to avenge the death, whatever the cost. As he begins unraveling clues, his behavior becomes so outrageous that he's obliged to turn in his badge, but the experience only emboldens him. Ryan eventually learns that his partner was caught up in a Puerto Rican gun-running scheme masterminded by a crook named Sweet Willie, who wants to foment revolutionary war.