Even when it looks like Irish writer/​director Martin McDonagh has one foot deeply set in his comfort zone – the tawdry world of dysfunctional male friendships – the other foot is somewhere else entirely, this time tramping the fertile ground of JFK conspiracy theories and America’s checkered history of destabilising nascent democracies around the globe. With his barnstorming Wild Horse Nine we’re in Chile circa 1972, and the populous is riding a wave of fevered awe following the election of socialist president, Salvador Allende.

Chris (John Malkovich) and Lee (Sam Rockwell) are a pair of jaded CIA lowlifes stationed in Chile, heading on a stint of leave to Rapa Nui (Easter Island) in the knowledge that Allende’s days are numbered and their (boot)boy Augusto Pinochet is waiting in the wings. At first, the pair appear to be on a break for a job well done – loping around, munching junk food, taking in the giant heads while the latter captures the landscape on his 8mm camera. Yet, it transpires that Lee is in fact on a secret mission, ones that demands that he takes stock of his friendship with the volatile Chris, who the powers that be (Steve Buscemi’s bureau chief MJ) believe might be about to air some very dirty laundry about his own activities inside the agency.

Although the film has much in common with the perma-bickering lads of In Bruges and the Banshees of Inisherin, McDonagh’s depiction of the CIA as louche, boorish reprobates in search for some kind of soul allies it more to the great novels of mid-century American malaise, such as Elmore Leonard’s ​’American Tabloid‘ or Don Delillo’s ​‘Libra’. Yet the large majority of the film’s enjoyment stems from the tika-taka repartee between Malkovich and Rockwell, flinging salty rejoinders back and forth and who play their roles as if they’re brothers, split by generations but with a bond that appears to transcend banal friendship. The film also offers a juicy inquiry of histories lost to elaborate cover-ups, and that the magnitude of information that some are set to take to the grave with them can sometimes be too much to bare.

The film keeps its cards fairly close to its chest in its knockabout first half, only laying down its flush of surprising melancholy and playful historical insight closer to the home stretch. There’s are some stellar supporting turns from Mariana di Girolamo, as a wide-eyed Chilean student who strikes a bond with Chris, Parker Posey as Lee’s snap-talking ball and chain, as well as Tom Waits in a moving, climactic cameo. While Rockwell seems to do his best work with McDonagh, and this is no exception, flowers go to Malkovich who delivers arguably his finest screen performance of the 21^st century, demonstrating that it takes a master to make a morally despicable character such as Chris not just worth rooting for, but empathising with.