For a man in his 70s, it is clear that William Friedkin (The Exorcist, The French Connection) has lost none of his appetite for exploring the seedy, darker sides of life. Chosen as the opener for this year’s Edinburgh Film Festival, Killer Joe is adapted from Tracy Letts’ first play about a dysfunctional and very damaged Texan family who make the mistake of asking the wrong man for help.

In the middle of a torrential downpour, Chris Smith (Emile Hirsch) arrives at the mobile home where his father, Ansel (Thomas Haden Church) and his step-mom Sharla (Gina Gershon) live. In serious debt after a bungled drug deal, he has come with a dangerous proposal – that they murder his mother and collect her $50,000 life insurance policy. The man for the job, according to Chris, is ‘Killer Joe’ Cooper (Matthew McConaughey), a police detective who moonlights as a professional hitman. Smooth, calculating and very much aware of the risks involved, Joe spells out the terms of transaction to the family. But when penniless Chris is unable to come up with the down payment, Joe agrees to accept collateral in the form of Chris' younger sister Dottie (Juno Temple).

Friedkin clearly delights in his base, incompetent, foul-mouthed characters and allows his actors full rein to go as far as they can with each of them. McConaughey, finally breaking out of his boring rom-com pattern, is perfectly cast as the smooth talking policeman who is the dubious moral compass of the story.