Before you start, please remove every bone in your body that is offended by violent language and violence.
While driving at night, Henry Hill, Jimmy Conway, and Tommy DeVito are surprised to find that the dead body in the trunk isn't totally dead. These three guys? They're wiseguys.
Flashback to Henry's childhood. He gets a part-time job at a cabstand run by local gangsters. He digs the extravagant mafia lifestyle and eventually quits school so he can work there full-time. Mob boss Paul "Paulie" Cicero becomes Henry's surrogate father and introduces Henry to Jimmy "The Gent", hijacker extraordinaire, and Tommy, another young thug with a fiery temper. Most of their criminal activities—including the robbery of an Air France cargo terminal—are centered upon Idlewild Airport (now John F. Kennedy International Airport).
Henry marries Karen. In 1970, Tommy whacks Billy Batts, a made man with the Gambino family, after Batts insults him. Batts? He's the guy in the trunk. Henry helps cover up the murder, burying Batts' dead body in the woods. Later, they're forced to move it when plans for a housing development are announced.
Henry also has a girlfriend, Janice. When Karen discovers that her husband is cheating, she goes to Janice's apartment, her daughters in tow, and harasses her. She's cool with turning a blind eye to what Henry does to make the cash that supports their comfy lifestyle; she's not cool with Janice. Karen then threatens to kill Henry, and he moves in with Janice until Paulie ultimately orders him to go back to his explosive wife.
Henry travels to Tampa with Jimmy for a job. They rough up a guy that owes Paulie money, but his sister, an FBI typist, turns them all in. Henry and Jimmy are both sentenced to 10 years in the slammer. Jimmy serves his time in Atlanta, while Henry does his with Paulie and several other members of the family in New York, where they cook indulgent Italian dinners because everybody knows smuggled salami is the tastiest salami. Meanwhile, Henry starts selling drugs to support his real family on the outside.
What, were you expecting white picket fences?
After four years, Henry gets released from the big house. He ignores Paulie's instruction to knock it off with the drugs and enlists the help of Jimmy and Tommy behind Paulie's back. In 1978, their crew pulls off the Lufthansa heist, netting them around $5 million. When several of their associates start flashing their big bucks around, Jimmy has them all whacked. Later, Tommy is tricked into thinking he's going to become a made man and be officially ordained into the family. Instead, he's murdered in revenge for the murder of Billy Batts.
What can we say? Things don't always go as planned in mafialand.
On May 11, 1980, Henry gets busted on narcotics charges in his driveway. Inside the house, Karen flushes $600,000 worth of drugs down the toilet, leaving the family broke. After Henry is released on bail, Paulie gives him a small chunk of change before turning his back on him. Jimmy also gives Karen a handout. Realizing that Jimmy is planning to kill him, Henry identifies both Jimmy and Paulie as big, bad mobsters in court and enters the Witness Protection Program with Karen and their kids. Abandoning the gangster lifestyle and being reducing to an average schnook devastates him.
Because who would be happy if their life wasn't in danger every day?
A postscript tells the audience that Paulie died in prison in 1988, Henry and Karen went splitsville in 1989, Jimmy is serving 20-to-life, and, after getting arrested on further drug charges in 1987, Henry is now clean—and still in hiding.