If you're alleging sex-slavery and abduction then I'll await more facts. Have you notified the authorities? Bust them hard if this it the case.
A person would have to go undercover in such places like this one discussed in this thread to gather proof. But I'll stick with my cynical, often correct assumption that swingers(sex addicts) are no different than heroin junkies. Their addiction(s) or addictive transference keep growing in numbers and depravity. I read articles and have spoken with authorities and watch many television shows which consistently conclude that, where there's a swinger there's a pedophile not far behind. Remember the VanDam girl in California, her parents were swingers and their free for all sexcapades delivered their own child to Satans own hands. God rest her soul.
Swingers = garbage in, garbage out.