Back street abortionists, sly groggers and late night illegal nightclub operators.
All flourished during the early years of World War II as off-duty American troops based in and around Auckland descended on the city in search of sex and booze.
Police used covert tactics to try and counter the associated problems and also enlisted members of the newly formed plain-clothed women's division to help.
The work was dangerous and a big step-up from the clerical duties some of them had been previously lumped with by male bosses who were uncomfortable with the feminine additions to their ranks.
But it did earn them a healthy respect with colleagues and members of the public - paving the way for future generations of women seeking careers in frontline policing.
Early recruits included Constable Elizabeth (Betty) McCarthy.
Betty joined up on February 29, 1944 - three years after the division was established.
She lived on the North Shore and travelled across the harbour each day to perform her duties in the city.
Betty became well-known for her diligence and bravery - never shying away from confrontation and stepping in wherever needed to make arrests and restore order around some of the inner city hot spots.
Police bosses sent her into numerous nightclubs as an undercover cop with one goal - to obtain evidence and secure prosecutions. Betty rose to the challenge.
So it was a huge blow to the force when, in May 1945, she became desperately ill and died after a short period of treatment in Auckland Hospital.
A full police funeral took place in Devonport and was the first ever held for a woman in New Zealand.
The casket was then transported by vehicular ferry to the city, marched up the length of Quay St by a troop of police officers and driven to Waikumete Cemetery where a graveside service drew a crowd of about 150 people.
It would be another seven years before policewomen got proper recognition and were issued with uniforms.
But it wasn't until 1973 that they got full equality and were permitted to do all the same duties as their male colleagues.
The efforts of Betty McCarthy and her pioneering colleagues still remain largely unsung.
Even cemetery records completed at the time of the 26-year-old's death fail to acknowledge the role she played in keeping her community safe - listing her occupation, simply, as "spinster".
- © Fairfax NZ News