American Buffalo (1996)

Donny Dubrow runs a junk shop. When he realizes that he sold a buffalo head nickel to a customer for a lot less than he could have gotten, he decides to steal it back. He also figures that as long as he's pulling the heist, he might as well go the extra mile and clean the guy out. Donny's accomplice in the robbery is his young gofer Bobby, a sort of surrogate son, and for whom the robbery will serve as a rite of manhood. However, Donny's long-time friend and poker buddy, Teach, has other plans. He wants to cut the kid out of the action and do the robbery himself. "Loyalty is fine," says Teach, "but business is business." Like the classic irresistible force, Teach assaults the immovable object of Donny's conscience. When Donny weakens, Bobby stumbles, and then, without hesitation or pity, Teach pounces. "We live like the cavemen," he says in a rare moment of self awareness, as he surveys the wreckage he has wrought.