The story of Lt. Joseph Petrosino, an Italian-American New York City police detective, who was assigned to investigate the Sicilian Mafia, which was beginning to become a major problem in New York. He did such a good job that the city sent him to Sicily to gather information on the Sicily/New York Mafia connections. He was murdered in Palermo by Mafia gunmen. The 1960 film Pay or Die! (1960) starring Ernest Borgnine was also based on his life.