Directed by William Friedkin. Starring Matthew McConaughey, Emile Hirsch, Thomas Haden Church, Gina Gershon, Juno Temple 18 cert, limited release, 102 min

Vividly amoral, Killer Joe triumphs as a white-trash, white-knuckle ride, writes DONALD CLARKE

IF I HAVE my sums right, William Friedkin has just made his best film in 27 years. The claustrophobic Bug (2006) saw the veteran director relishing the opportunity to exercise his passion for the seedier side of existence. But Killer Joe – like Bug, based on a play by Tracy Letts – finds him grinding the gears even more furiously. If you’ve always longed to see a version of Double Indemnity played out by in-bred, under-educated psychopaths, then your time has finally come.

Emile Hirsch (creased, frustrated) and Thomas Haden Church (vacant, distracted) play, respectively, a son, Chris, and a father, Ansel, living grimily in a Texas trailer that may have once seen very slightly better days.

Desperate for money to pay obscurely accrued debts, the sordid family enter into an appalling scheme: they will arrange to have Chris’s estranged mother assassinated and then share the life insurance payout with the killer. The agent of their plot turns out to be a Mephistophelean police officer with unblinking eyes and the stiffest of backs.

We do not mean to damn with faint praise when we say that, playing the titular murderer, Matthew McConaughey has never been better. Inhumanly efficient, savagely amoral, Joe makes everybody he meets seem like a member of a less evolved species.

Here we encounter one of the film’s many moral ambiguities: the supposed villain is allowed more dignity than any of the more compromised, more forgivably flawed conspirators. Among the clan, only Dottie (a well-cast Juno Temple), Chris’s slightly simple- minded sister, emerges as someone you wouldn’t cross a busy train track to avoid. And that poor girl’s body is sold to Joe as collateral.

If Letts were not so familiar with the Texas border country, his depiction of trailer trash (no other cliché will do) would seem unforgivably offensive. As it stands, the film – bloodier and more twisted than any Jacobean tragedy – emerges as a small masterpiece of applied grotesquerie.

Killer Joe’s origins as a play do show through: the story develops more through dialogue than action. But, working with distinguished cinematographer Caleb Deschanel, Friedkin applies such striking visual grime that the occasional staginess never becomes oppressive.

Horrid in a good way.