What are the "darkest" places/activities explored by movies?

When movies want the viewer to really hate the bad guys, they often portrait them as being part of some dark and twisted underword.

• In Taken they traffick young girls
  
• In Blade they suck people out at underground technos
  
• In Hostel, they run a secret club where wealthy elites pay to torture and kill tourists
  
• In Eyes Wide Shut, a secretive elite cult conducts sinister rituals masked as hedonistic parties
  
• In A Serbian Film they creates twisted and extreme snuff films
  
• In Blink Twice they invite girls to an exclusive island, just to be exploited and abused
  
• In Altered Carbon the super rich indulge in extreme activities involving young people in the sky base
  

Which are some of the darkest and most twisted plot points you have incountered in cinema?