There’s a whiff of nostalgia from Harry Michell’s black comedy about Christian assassins on the rampage, and it’s mostly the better for it. Its decidedly British feel – hints of Clockwise and Nuns on the Run – makes up for some of the ideological messiness and provides an unexpectedly cosy base note. Perhaps that’s why many of the narrative turns feel fresh, even while the overriding sentiment – that all fundamentalism is fundamentally flawed – is nothing new.

Harry Melling, best known to most as Dudley Dursley, ably holds the centre with a touching performance as Tim, whose child-like literalness is steered by his more volatile brother, Vic (an equally impressive Tom Brooke) – who tends to do the actual murdering. Tim’s state of mind is echoed and intensified by an incongruously placed male voice choir, which adds a pleasingly surreal touch, and the gradual shattering of his moral certainty is punctuated by jarring flashes of real or imagined violence.

Bringing the biggest laughs as a foul-mouthed detective with no social graces is the ever-brilliant Anna Maxwell Martin, and it’s just as well; her character adds little tension otherwise. Vinette Robinson narrowly escapes the same fate as a gentle author who begins to expand Tim’s horizons but gets little development of her own. Roger Allam and Derek Jacobi have a whale of a time providing extremist bookends – one a deliciously observed, barely-veiled impression of the late Christopher Hitchens, the other an abusive preacher.

In the end, the film tries to land too many blows, from a blink-and-you’ll-miss-it sideswipe at Islamophobia to an unexamined suggestion that childhood trauma opens the door to radicalisation. The target is too big, and it’s carrying too much – but it still succeeds in bringing the laughs.

RATING: 3/5

INFORMATION

CAST: Harry Melling, Tom Brooke, Anna Maxwell Martin, Roger Allam, Derek Jacobi, Vinette Robinson

DIRECTOR: Harry Michell

WRITERS: Harry Michell, Jamie Fraser

SYNOPSIS: Orphaned, church-reared brothers Tim and Vic head to Ilkley to assassinate the keynote speaker at the literary festival: an atheist firebrand professor.