Chris Smith (played by Emile Hirsch) is in a bind. He owes a loan-shark a fair bit of money, and the man has threatened to kill him if he does not produce the money within a few days. He does not have the money. He strikes upon a get-rich-quick plan: have his estranged mother killed and collect on the insurance money. He involves his father, Ansel (Thomas Haden Church), who buys into the deal for a share of the profit (him and Chris' mother are divorced and don't see eye-to-eye, so it wasn't a tough sell). Ansel then involves his 2nd wife, Sharla (Gina Gershon) and, due to her finding out about the plan, his daughter, Chris' sister, Dottie (Juno Temple). They hire a professional killer (who happens to also be a cop), "Killer Joe" Cooper (Matthew McConaughey). When they cannot pay him upfront, they reach an unusual deal on how to retain his services. This complicates matters, a lot.