Bad cop, worse cop: "Filth"

I wound up enjoying Filth - which struck me as the best film of its type since In Bruges - though it seems at first to illustrate a tendency peculiar to the British film industry: that inclination to snigger (and encourage sniggering) at the kind of material others have taken deadly seriously. The source is Irvine Welsh's 1998 novel, which emerged into that post-Trainspotting, Britpoppy dreamtime, and comprised this infamously profane author's take on the Bad Lieutenant figure; yet where Abel Ferrara went after the unholy trilogy of religion, sex and power with an unblinking, agonised, tough-to-watch sincerity, Jon S. Baird's adaptation serves these elements up as a Viz-level cartoon for broad-minded audiences, so hellbent on appearing non-PC that it pridefully reclaims the word "spastic" as an insult, and lays "Will You Still Love Me Tomorrow?" over an interlude of frenzied phone sex. All of which is to acknowledge that you'll either love it or want to leave after an hour, in need of a very hot shower - but then you can't say the title hasn't warned you.

Welsh's conceit was to take the kind of figure who would, in the real world, be terrifying - Detective Sergeant Bruce Robertson (here played by James McAvoy), a syphilitic sociopath angling for a promotion in the middle of a murder investigation - and submit him to a grilling from within and without, in the process revealing him as as much a Scottish archetype as the pregnant, deep-fried Mars Bar-scoffing alkies he stalks the mean streets of Edinburgh spitting and sneering at. One might wonder how much this pretty filthy, disreputable soul has been cleaned up for multiplex consumption; the answer, despite the presence on the sidelines of a friendly widow (Joanne Froggatt) and her adorable son, is admirably "not much", and - as with Danny Boyle's film of Trainspotting, the last truly notable Welsh adaptation - Baird has found ways of ushering us past the novel's episodic style and jarring tonal shifts. 

Put simply: it would be very easy to get this wrong, as evidenced by that overstuffed bargain-bin of British black comedies that crashed and burned in the effort to be edgy or daring. Filth, for its part, gets by on an unshakeable energy and confidence. Though recognisably of Welsh's world, it's determined to be very much its own film: grungy, seedy, wiggy, confounding. Baird somehow makes coherent a Reeperbahn jolly that begins with a mashed-up Eddie Marsan voguing to electro and ends with McAvoy getting spooked by a pig-faced figure (apparently drawn after Matthew Barney) at the foot of his bed; he's also perfectly content to throw in a singing David Soul cameo that the kids getting off on all the cussing and shagging won't have a clue what to make of. (The cultural reference points are decidedly pre-millennial: while the world awaits Lenny Abrahamson's Frank, I suspect some viewers will take the bizarro-world presence of Frank Sidebottom as one of Baird's own inventions.)

Sometimes Baird appears to be having so much scabrous fun that he forgets about the niceties of plot, yet his shock tactics are forever modulated by an ensemble of emergent national treasures, who allow themselves to be mocked, splattered or otherwise tarnished, and busily set about creating characters that pop out of the screen: Jim Broadbent (with distended forehead) as an Australian psychiatrist who effectively takes the place of the novel's tapeworm, Marsan and Shirley Henderson - so indelibly numbed and raw as the grief-stricken parents in TV's Southcliffe - going to the opposite extreme as a patsy Freemason and his blowsy, hot-to-trot wife, John Sessions as Robertson's hemming-and-hawing, palpably impotent superior.

The chief selling point here, though, may lie in watching McAvoy shake off the last vestiges of his boy-next-door image: chipshop-haired, ratty and gingery of beard, sunken of eye, this is a performance commendably lacking in vanity, such that the actor can happily enter into a scene in which Robertson sexually disappoints the stationhouse's libidinous secretary (Pollyanna McIntosh), and another wherein a female colleague (Imogen Poots, increasingly impressive) further cuts through the character's swollen ego. If Filth attempts a bad-cop-worse-cop interrogation of the Scottish hardman, roughing delicate viewers up between its bouts of broad, popcorn-snorting knockabout, McAvoy places a critical intelligence at the centre of it - or, at least, enough of same to make Robertson's final mise en abîme oddly affecting. Sample dialogue: "Did you do her up the arse?" "Where else is there? Pussy's for faggots." Your grandmother might prefer Sunshine on Leith, all told.

Filth is in cinemas nationwide.