|“|| "They call him the Rabbi!"|
"Because he's a rabbi..."
|~ A conversation that is repeated throughout the movie|
The Rabbi is one of the two main antagonists of the movie Lucky Number Slevin.
Twenty years before the main events of the movie, the Rabbi was the business partner of The Boss. They made money by fixing horse races and when a man called Max accidentally gets wind of the manipulation and sets a lot of money on the horse supposed to win, the two decide to set an example. They have Max ambushed when he returns to his car. Max is kidnapped and tortured by the Rabbi and the Boss. When Max begs to be returned to his family, the two reveal that Max' family is already dead. Indeed, one of their henchmen headed home to Max' house and killed his wife but Goodkat, the killer hired to murder Max' son, secretly left the boy alive and took him in on his own.
Eventually, the Boss and the Rabbi part ways and even become rivals. Both build up a criminal empire but - out of fear of being eliminated by the other - both never leave their penthouse apartments ever again. Both men have their headquarters in penthouse apartments on the same street and are able to watch the other man's office window from their own office.
Unbeknownst to the Rabbi and the Boss, Goodkat raised the spared boy as his own son and the two plotted revenge on the two mob bosses. To set off the events, the boy - now known as Slevin - killed the Bosses son. The Boss believes that this was done by the Rabbi and decides that the Rabbi's son must also be killed. He has a guy who owes him a lot of money brought to his office to do the deed. He is unaware that this guy's identity has been taken by Slevin.
Moments after he has been returned to his apartment, Slevin is picked up by two of the Rabbi's men who deliver him to the Rabbi. The Rabbi, who also believes that Slevin is the person whose identity he took on, demands that Slevin pays him back the money "Nick" owes him. He soon realizes that Slevin is not Nick but demands the money anyhow as to not endanger a deal he has with Goodkat, who is manipulating both the Rabbi and the Boss from behind the scenes. Moments before he leaves the Rabbi's office, Slevin turns around to ask him a question but the Rabbi assumes that Slevin wants to attack him and swiftly draws a shotgun from under his table. This shotgun, which the Rabbi used twenty years ago, confirms to Slevin that the Rabbi is indeed the person he is looking for.
Together with Goodkat, Slevin murders the Rabbi's son - seemingly because he was forced by the Boss. However, Slevin then returns to the Rabbi, who is not yet aware of the death of his son and hands him a suitcase, claiming that the Rabbi's money is inside. However, when the Rabbi opens the suitcase, he is knocked out by Slevin with a blow to the head.
When the Rabbi wakes up, he finds himself strapped to a chair in the penthouse of the Boss, which he recognizes from back when they were partners. To his surprise, the Boss is tied to a chair as well; both men are sitting with the back to the other. Once the two recognize their old partners sitting behind them, they blame each other for the attacks on their businesses, unaware that the attacks were actually carried out by Slevin and Goodkat. During this conversation, the Boss spitefully tells the Rabbi that he had his son executed.
The conversation is disrupted when Slevin arrives in the room. The Rabbi tries to bribe Slevin because he expects that Slevin is working for somebody else. Slevin, however, reveals that he cannot be bribed because everything he did was his own plan. He reveals his entire plan and backstory to them and thus reveals that they are responsible for the death of his family. He then kills the two men the same way they killed his father - by putting a plastic bag over their heads and taping it shut, suffocating the two to death and avenging his parents.