In 1960, Lorenzo works as a MTA bus driver in Belmont, a working-class Italian-American neighborhood in The Bronx, with his wife Rosina and his nine-year old son Calogero. Calogero becomes enamored of the criminal life and Mafia presence in his neighborhood, led by Sonny. One day, Calogero witnesses a murder committed by Sonny in defense of a friend being assaulted. When Calogero chooses to keep quiet when questioned by NYPD detectives, Sonny takes a liking to him and gives him the nickname “C”. Sonny’s men offer Lorenzo a better paying job, but preferring a law-abiding life as a bus driver, politely declines. Sonny befriends Calogero and introduces him to his crew. Calogero earns tips amounting to $600 working in the Mafia bar and throwing dice, and is admonished harshly by Lorenzo when he discovers the cash. Lorenzo speaks severely to Sonny, returns the money, and angrily warns him to keep away from Calogero.
Eight years later, a 17-year old Calogero has grown into a young man who has been visiting Sonny regularly without his father’s knowledge. Calogero is also part of a gang of local Italian-American boys, which concerns Sonny. Later, Calogero meets a black girl, Jane, and they develop a tentative friendship. Despite the high level of racial tension and dislike between Italian-Americans and blacks in the neighborhood, Calogero arranges a date with Jane. He asks for advice from both his father and Sonny, with the latter lending Calogero his car. Later, Calogero’s friends beat up black cyclists who ride through their neighborhood, despite Calogero’s attempts to defend them. One of the cyclists turns out to be Jane’s brother, and he mistakes Calogero for one of the assailants and accuses him of beating him up when he and Jane meet for their date. Calogero loses his temper over the accusation, and calls him a nigger, which he instantly regrets. Jane leaves with her brother.
At home, Calogero is confronted by his father who had just seen him driving Sonny’s car. An argument ensues and Calogero storms out. Shortly thereafter, Calogero is confronted by Sonny and his crew, who found a bomb on Sonny’s car and suspected Calogero of planning to assassinate him. Calogero tearfully pleads his unwavering dedication to Sonny. Sonny recognizes Calogero’s innocence and allows him to leave. The black boys egg the Italian-American boys’ usual spot in retaliation for the previous beating, and Calogero’s friends make a plan to strike back using Molotov cocktails. They force Calogero to participate, but while on their way, Sonny stops their car and orders Calogero out. Calogero catches up with Jane, who tells him that her brother had since admitted that the boy who beat him up was not Calogero. Jane and Calogero make amends, but Calogero suddenly remembers his friends’ plans to attack Jane’s neighborhood, and the two rush to stop them. Calogero and Jane arrive to find the Italian-American boys’ car in flames. During the attack, a black boy threw an unbroken Molotov cocktail back at the car. Entering through the window, it ignites the remaining Molotov cocktails, resulting in an explosion that kills everyone inside.
Calogero rushes into the crowded Mafia bar to thank Sonny for saving his life, but an assailant shoots Sonny in the back of the head before Calogero can warn him. Calogero later learns that the assailant was the son of the man he witnessed Sonny kill eight years earlier. At Sonny’s funeral, countless people come to pay their respects. When the crowd disperses, a lone man, Carmine, visits the funeral, claiming that Sonny once saved his life as well. Calogero does not recognize Carmine until he sees a scar on his forehead and realizes he was the man being assaulted whom Sonny had defended when he committed the murder. Carmine tells Calogero that he will be filling in for Sonny in the neighborhood for the time being, and promises Calogero help should he ever need. Carmine leaves just as Calogero’s father unexpectedly arrives to pay his respects to Sonny. Lorenzo thanks him for saving his son’s life and admits that he had never hated him, but that he had resented him for making Calogero grow up so quickly. Calogero and his father walk home together as Calogero narrates the lessons he learned from his two mentors.