A Darker Fifty Shades: The Fetish Set (2015)

Four beautiful women attend a fetish convention hoping to make some easy money, but find themselves thrown into a dark, underground world of obsession and murder when a deformed, sadistic serial killer (Bill Oberst Jr.) sets his sights on the quartet. Now, their friendship and personal limits will be torn apart as they struggle to survive the most brutal weekend of their lives.

Thriller