I thought this did a great job of cranking up the tension, although it took a while to get going. Maybe I'm naive but I honestly thought the men seemed nice and I was curious about how the film would turn dark, as per the massive spoiler warning at the start of the film. It kept me guessing. I was wondering why Slater wasn't making moves on Frieda cause he was clearly into her. Lol.
The more I think about it, the more I want to watch it again. I have a feeling that on second viewing I will feel like an idiot for not spotting so much stuff.
The final scene didn't work for me though. I don't know how Frieda could have control over Slater. The memory loss perfume won't make him forget the previous abuse he did to her, and won't change his psychopathic personality.
Also fuck the trigger warning. Spoiling the plot of a mystery thriller is a dick move.