A young woman (maybe nineteen), leads a fairly promiscuous lifestyle, until one day, her friends (and relatives, if you want to take it that direction) stage an intervention, to try to turn her from her lusty ways. In addition to her friends and family, the intervention is attended by other pillars of the community, including one of her teachers and a preacher. Humiliated by the episode, she vows that not only will she not change her ways, she will set about seducing every person at the intervention, starting with her friends (both male and female), and moving on to the other people at the intervention.
An alternate (but less plausible, as if the idea above isn't implausable enough) idea would be for the intervention itself to turn into an orgy.
An alternate (but less plausible, as if the idea above isn't implausable enough) idea would be for the intervention itself to turn into an orgy.