Two privileged teens—a strict disciplinarian’s resentful stepdaughter (Anya Taylor-Joy) and her emotionless friend (Olivia Cooke)—explore their dark sides in this transgressive psychological thriller, set amid the manicured estates and equestrian pursuits of suburban Connecticut. The girls’ debate over the ethics of killing soon escalates into a plot to blackmail a local drug dealer (Anton Yelchin) so he will off the stepdad. Writer-director Cory Finley uses the clipped dialogue of film noir to heighten the sense of menace; the shadowy luxe interiors were shot by Lyle Vincent.