Fenced In
Unfortunate thief Simon picks the wrong person to rob, and makes a deal to save his life. He thought he would only be selling himself for the night, but it turns out to be for good. He is taken to a gated community where the residents can use him at will; and they do, repeatedly. He is used and abused, and slowly but surely loses himself.
Or: A man who didn't know what he was getting into is subjected to the dark whims of some very bad people.