The Connection (1962)

In a cramped and dirty apartment, eight junkies variously goof off, chat and play jazz music while waiting for their heroin connection to show up. They've also struck a deal with documentary filmmaker Jim Dunn (William Redfield) : They'll let him film them provided he pays for their drugs. When the dealer, Cowboy (Carl Lee), arrives, he's suspicious of the filmmaker and his camera, enough so that Dunn considers trying heroin himself to prove he's no narc and to better understand his subjects.