Morals Squad (1960)

A NYC vice-squad detective has traced the headquarters of the city's largest vice-ring to a lower east-side bar catering to businessmen to want to entertain their out-of-town clients properly by supplying them with call-girls. He is known by the madam, so he assigns a detective to infiltrate the gang and get the necessary evidence for prosecution. The undercover cop is recognized by one of the prostitutes as he had once picked her up on a shoplifting charge. Detective O'Connell then assigns a policewoman to get a job as one of the ring's call-girls.