Surprised nobody has mentioned this idea.
Milady is hosting or attending a very posh private function at a manor house type location. Everyone whe is anyone is present. She is dressed in the latest expensive couture, designer labels, Manolo Blahniks etc. with an expensive hairdo. Maybe she is slightly prudish. My favourite twist is that she is an exceptionally well-preserved older lady, in the style of Helen Mirren in "the Cook, The Thief..." or maybe Joan Collins sort of things, with the long gloves etc.
The hero of the story resents her for some past injustice. He invites her into a side room midway through the party, on a reasonable pretext. There he forces himself on her using violence, mind control, blackmail or similar. Maybe he uses excessive violence just for his own pleasure, or maybe just enough to fuck her stupid, including degrading insults etc.
Dishevelled, maybe covered in semen in obvious places, messed up hair, shit on lips from ass-to-mouth, semen dripping out of anus, red face from slapping, tears in clothing, confiscated panties, she has no choice but to rejoin and attempt to continue hosting the party, or trying to be the belle of the ball.
Maybe her favoured beau whom she wished to attract figures it out and takes her to one side and hijacks the idea and does her again, to her horror. Or maybe he just gets it on with her like she wants, and finds that under her clothes she has filthy graffiti written on her body in green ballpoint by her erstwhile rapist.
For the happy ending fans she might fall under the spell of her assailant's cock or something like that. The opposing faction might have her living in fear of a repeat assault, which might even come true in a sequel.
Can I have a credit in the byline please?