Confessions of the sex slaves (1977)

The plot has pretty, middle-class Caucasian girls (college students, runaways etc.) being kidnapped right of the streets of Zurich and Montreal(!), and after being beaten, raped, and hooked on heroin, they are sent to Amsterdam to work as zombified strippers and prostitutes in a nightclub called the Moulin Rouge. A female reporter is investigating the disappearance of one girl and ends up on the trail of the slavers.