Susie and Simon Have Fun With Anne and Wendy
When her friend suffers at the hands of a man she and another friend seek revenge. Sort off. Actually that doesn't really describe it at all. So the easiest thing is to read it.
Tags: Ma/Fa, Coercion, Drunk/Drugged, NonConsensual, Heterosexual, Fiction, BDSM, Humiliation, Sadistic