Sean Bean plays a British undercover spook forced to go "off reservation" in a desperate bid to thwart an Islamic terrorist cell operating in London. His implacable foe is Ash (Abhin Galeya), a law student turned Moslem avenger steered by Peter Polycarpou's radical cleric. Just one step behind the fanatics, Bean doesn't know who to trust in this timely debut thriller from writer-director Hadi Hajaig.
A 'Cleanskin' is a noun describing an anonymous terrorist trading on the fact he's unknown to the security forces.
So it's a bit of a surprise that Ash (Galeya) isn't on nodding terms with the anti-terrorist squad such is his determination to let everyone clock he's a lethal freedom fighter.
He wanders through public places wearing a black balaclava waving an automatic pistol, leaves an electronic trail via mobile phones that a six-year-old could follow and pops up on so many CCTV feeds that he should have his own reality show.
And this is the problem with writer-director Hadi Hajaig's contemporary thriller: the lumbering narrative - overburdened with flashbacks - careers along in a collapsing arc of inauthenticity.
And Ash isn't the worst offender. That dubious honour goes to Sean Bean's gruff Yorkshire agent Ewan, an army veteran whose every brush with the bad guys ends up with him being disarmed, wrong-footed and saddled with the worst outcome.
After Ewan allows a slab of Semtex to fall into the wrong hands (it ends up blowing up a restaurant), he has to go rogue in a desperate bid to corner an Islamic terrorist cell before they carry out their next atrocity.
They're led by the charismatic Ash, a former law student who's been pretty much westernised (he's got a nice English rose girlfriend - Tuppence Middleton; no relation) but is corrupted by nasty radical cleric Nabil (Polycarpou).
This is the most intriguing aspect of the story but Hajaig squanders it with a reality-defying subplot involving a ruthless Middle Eastern assassin who likes Mr Bean and killing babies.
There's too much going on and the director doesn't appear to know which elements to retain (Bean's character, for instance, is a complete mystery) and which to jettison (a barking conspiracy side order involving top-level complicity).
At times, it's almost as funny as Four Lions. The trouble is, it's not meant to be comedy.