In 1975 Sydney journalist and campaigner against rampant property development Juanita Nelson disappeared after a meeting with reputed crime boss Abe Saffron.
Her body was never found and nobody was ever charged with her disappearance and likely murder.
In a two-part series, family members Keiran McGee and Pip Rey worked with journalists from ABC's Unravel True Crime podcast series to see if they could uncover what happened when Nelson visited the Carousel Club.
McGee said Nelson's disappearance had become "family folklore" but with some members consumed by the need to know what happened.
"It's always been one of those things where there have been certain members of the family like my Aunty Mary," McGee said.
"They just spent their life wanting to know and it really devastated them - that was going to be one of the motivators [for the series].
"This is a story that comes up in the news every couple of years. It's turned over for entertainment rather than for trying to find out anything new.
"To position Juanita as her own person, that was really my goal with this.
"My question when I started out was to find out who Juanita was and find out what it was that she was doing that led to her disappearance. I really wanted it to be focused on her."
McGee said she had been "banging on" about the story to friends for years and, working in the documentary film industry, she was always trying to get producers interested.
But nothing came together until the ABC paired her and Rey up with the Unravel podcast team.
McGee and Rey are front and centre in the investigation, even though they are not journalists - which is where the podcast team came in very handy.
"Auntie Pip and I are just family," McGee said.
"We don't have the skills or the understanding of what was required and so working with actual journalists who worked alongside us the entire way and guided us and helped us with questions and how to approach people it was so important.
"I learned so much by working with this team - it was an incredible privilege."
There were also some risks, as the pair interviewed underworld figures who knew a lot more tricks than the two amateur sleuths.
To keep the danger to a minimum, they had to take part in risk assessments before approaching the crims - which McGee said doesn't spring to mind when starting work on a true crime series.
"I spoke to a couple of people who had dangerous backgrounds and I have to say they were really nice," McGee said.
"This is not a world I have any kind of experience of, but they said what they would do and they said what they wouldn't do.
"I obviously knew they were going to lie to me so I wasn't expecting anything beyond that but if they said they would call at a certain time they called at that time. They showed up at the time they'd agreed to."
As for what happened to Nelson, McGee doesn't hold out any hope that she managed to survive her trip through the underworld. She's certain Nelson died not long after that Carousel Club visit.
What shocked her was "the levels of corruption" required to cover up what happened.
"This crime was so brazen," she said.
"A lot of the interviewees, I asked them why it seems that these people were so confident in what they were going to do. They took a woman from a street in the middle of the day and disappeared her in the most obvious of scenarios.
"Arthur King, one of the people we interviewed, said this is a crime that should have been solved in three days.
"She went to the Carousel Club and the last person who saw her alive had been trying to contact her via various means for a little while - and he was not investigated.
"These people were so confident that they could do this. Why were they so confident and how did they get away with it?
"It's instructive for us all today because they've still gotten away with it."
Juanita - A Family Mystery: Premieres Tuesday 7 September at 8.30pm on ABC iview and ABC TV.