After the agonising tension and brutality of their Oscar-winning opus No Country For Old Men, writer-directors Joel and Ethan Coen return to comedic territory with a tale of espionage and infidelity.

Burn After Reading is not classic Coen brothers fare, but there are enough flashes of brilliance to keep us smirking for almost the entire 95 minutes.

A large proportion of those laughs are reserved for Brad Pitt, who gamely throws himself into the role of a dim-witted gym employee. His double-act with Frances McDormand’s cosmetic-surgery-obsessed spinster is a joy to behold.

The coup de grace is a genius invention which will be the envy of every frustrated housewife.

Former CIA agent Osbourne Cox (John Malkovich) pens his memoirs, but an electronic copy of the manuscript inadvertently ends up in the possession of gym employee Chad Feldheimer (Pitt) and co-worker Linda Litzke (Frances McDormand).

She desperately needs cash to enhance her drooping attributes, so Chad and Linda try to blackmail Osbourne in exchange for the safe return of the disk containing his tome.

But he refuses to pay the ransom so Chad and Linda head to the Russian embassy, intent on selling his secrets to the enemy.

Meanwhile, Osbourne’s hard-nosed wife Katie (Tilda Swinton) is engaged in an extra-marital affair with womaniser Harry Pfarrer (George Clooney), who has also begun dating Linda.

Unbeknown to all of them, the CIA is monitoring every move, determined to find out who is leaking top-secret information to the Russians.

Burn After Reading is peppered with colourful, idiosyncratic characters we love and loathe in equal measure. Malkovich relishes his role as a hard-drinking curmudgeon who cannot believe the audacity and incompetence of his two would-be blackmailers.

Clooney essays another charming oddball, not a million miles away from Intolerable Cruelty and O Brother, Where Art Thou?, while McDormand brings a touching vulnerability to her opportunist.