Unmarked spoilers are ahead, per Spoilers Off rule.
The rape scene. Everything about it, from the buildup of tension as the other oil workers get increasingly creepy to the actual act itself, as well as Matt being beaten to death for trying to stop it. It manages to be utterly disturbing and heartbreaking.
Cory's second visit to Natalie's parents is a milder example, but after all that's happened so far, each room he finds empty increases the expectation that he'll find one or both of them dead in the next.
