Mercy (2000) (IMDB) is a late entry in the erotic thriller genre that dominated in the 80s and 90s. This kind of movie was getting stale by the turn of the millennium, and many scenes seem strongly reminiscent of Body Double (previously discussed) and Se7en.
It starts, as usual for this kind of film, with a dead body. This time it’s a nude woman, one of a series with signs of being tied up, bite marks all over her torso, and her eyelids cut off. Detective Catherine Palmer (Ellen Barkin) forms a relationship with Vickie (Peta Wilson), a friend (and likely more) of the victim, Dorothy.
Palmer searches the victim’s home and finds a hidden briefcase full of BDSM toys, and pictures of the victim being dominated by a masked man. She calls up a pro dominatrix via Vice and visits her dungeon in an upscale building.
Palmer: “And what’s your area of expertise, Terry?”
Dominatrix: “Japanese silk ropes and the finer psychological aspects of the relationship between the players. I can tie you so you can’t twitch your ass cheeks. Of course it’s time consuming. It’ll cost you a couple of grand. Mostly the businessmen like that.”