"Killer" Joe Cooper (Matthew McConaughey) is a Dallas detective who doubles as a hit-man with the charm of a Southern gentleman. Chris (Emile Hirsch) hires Joe to kill his mother, in order to collect her life insurance and pay off his debts. When Chris is unable to pay for the service up front, Joe takes Chris's sister Dottie (Juno Temple) as a retainer until he can be paid.