Z never leaves The Island, a tropical nation. Consensual sex work is legal. Public nudity is only allowed on two beaches.
Z's mother was an at-home nudist and single mom. Z and her sister, Fran, were naked at home once they no longer needed diapers. When Z was thirteen she attempted to give a blow job to a 10yo boy. (He quickly lost interest and Z quit her attempt.) Her mom had no problem with Z exploring her sexuality.
A month later the young sisters lost their mom to a nasty pneumonia. Child Protective Services found a tiny house where Z and Fran can live together with brief daily CPS visits.
At 16, Z gets a boyfriend and soon she and her sister give their virginity to 16yo Rick May. The girls share Rick as Team Girlfriend. Even Rick's parents believe Rick and Z are boyfriend and girlfriend with little sister, Fran, always welcome.
Two years later Z, now 18, becomes a sex worker when that 10yo boy, now 15, wants that blowjob and more.
Z writes an ad. Her first client owns RITC, Round Island Tour Company. Z and Fran host RITC's Nude Beach Tour for cruise ship passengers. They are the inspiration for RITC's late-night Copulating Couples Cruise.
Z is lucky. Her first client is rich and treats her well. She services a number of interesting clients. She pleases two more rich clients: a married couple, Mel and Alice Brand, and an about 40yo single man, Paul Packet III.
But the sisters are unlucky that Rick must return to Chicago with his parents. He attends UIC and is set for Harvard Law with a full-ride assuming excellent grades. (Parents are senior lawyers with a Chicago based law firm.) The only bright side is the sisters will be paid to keep the place ready for short term use for other senior lawyers. They can use the place when it's not otherwise occupied.