After an illegal abortion at the behest of her faithless lover (Raul Julia), lost innocent Helen (Kitty Winn) finds solace with small-time crook Bobby (Al Pacino), a regular in Manhattan's "Needle Park." As Bobby shows her around his Upper West Side world, the two become inseparable. When Helen realizes that Bobby is a full-blown junkie, she joins him in addiction, and their downward spiral begins in earnest. Weathering overdoses, prostitution, betrayals, and a "panic" after a major bust, the pair manages to stick together, the habit sealing their fate.