The Killer Inside Me

Name of Joyce Lakeland. Lives about four or five miles out on Derrick Road past the old Branch place.
Oh, I know the old Branch place. She a hustling lady, Bob?
Well, I guess so, but she's - she's been pretty decent about it.

—Sheriff Bob Maples and Lou Ford

This 2010 film, based of the novel by Jim Thompson, is unflinchingly violent and deliberately disturbing. It begins when the polite, seemingly normal Lou Ford is sent to encourage local prostitute Joyce Lakeland to leave town. The confrontation leads to him beating her with a belt, and their romance begins. Together they concoct a plan to scam money from the wealthy Chester Conway. But Lou secretly had an even darker plan for Joyce. He beats Joyce unconscious and shoots Chester's son, making it appear as if the two of them got into a fight. From there he must keep committing more murders to cover up his crimes, and also, because he enjoys it.

Tropes used in The Killer Inside Me include:

Freudian Excuse: The camera pans over the main character's bookshelf, lingering prominently on a volume of Freud. He immediately takes a bible off the same shelf, opens it, and finds forgotten photographs of his mother's sadomasochistic sex life.
No-Holds-Barred Beatdown: Lou gives one of these to both Joyce and Amy in graphic, prolonged, horrific scenes. And they both die. Except not really, because Joyce is revealed to be alive at the end, although disfigured--and then he immediately kills her for real.
Southern-Fried Genius: Lou Ford is an Ax Crazy version of this trope.