Festival (18)

Annie Griffin is best known as creator of the acerbic, astute Channel 4 comedy-drama The Book Group, and her humour here is even more trenchant. The film is partly improvised by the cast, a game ensemble who never balk at merging with the crowd and humiliating themselves in public. Festival's exquisite "ouch" factor kicks in right at the start, when ingenue Faith (Lyndsey Marshal), barely off the bus, hits the Royal Mile and pesters passers-by with flyers for her one-woman show about Dorothy Wordsworth. How we wince for her and her olde-Lakelands mob cap - then we see the shots of all the real-life gurners and grinners hustling for attention in mime make-up and powdered wigs, and realise that Faith is no more desperate than anyone else in town.

Festival is surpassingly cruel, but not a little tender, about the more noble, largely doomed end of the Fringe: those quixotic sessions where earnest, high-minded troupers spill their pain over three punters in the breakfast slot. There's Faith, struggling to evoke Wordsworth's daffodils with a badly-cued yellow light in a church hall ("I love this space!"); Brother Mike (hulking, lugubrious Clive Russell), with his too-close-to-the-bone show about paedophile priests; and the spaced-out Canadian avant-gardists with their mixed-media dance experience ("The fishermen are coming home! Their boats are full of tuna!").

But it's in the abjection of the comedy circuit that Festival's real pith is focused - which is kind of typical, you might say, all those bigmouthed stand-ups upstaging the real, you know, art. There are two Irish comics, Tommy O'Dwyer (Chris O'Dowd) and his mate Conor (Billy Carter), both touting that "soft-spoken, wry, gently boozy Irish observational humour" that's invariably the first box you tick off in the comedy listings - except that Conor also works with a glove puppet. Although they can't resist upstaging each other, they're mutually dependent for reassurance that they haven't lost their sparkle. Tommy, eyes on that elusive fifth star in the review ratings, makes overtures to Joan (Daniela Nardini), a radio reporter who happens to be on the film's thinly-disguised counterpart of the Perrier jury. When she agrees to go to a hotel room with him, Nardini's no-nonsense lust, paired with O'Dowd's impersonation of a terrified teddy bear, is something to behold.

Then there's Sean Sullivan (Stephen Mangan), an insecure, egotistical, highly successful British TV comic with his eye on Hollywood: he's in town as a jury member, but has total contempt for everyone else's efforts and ostentatiously chooses to go "incognito" in a conspicuous red baseball cap. Sullivan is a prickly ball of quivering pique, brutally exploiting his long-suffering, recovering-alcoholic PA Petra (Raquel Cassidy), and womanising with little-boyish compulsion. One of his pick-ups is brash, pneumatic Nicky Romanowski (Lucy Punch), who turns out to be more than his match for sheer monstrosity. She's a depressingly unfunny but ferociously enthusiastic north-London stand-up - "I just love comedy!" she shrieks, with lead in her voice - whose lack of talent probably won't stand in the way of success. Punch and Mangan are mesmerisingly gruesome together, especially in the scene where Nicky jerks Sullivan off while practising her Jewish-mother routine. Festival's crisp intelligence allows it to get away with some louche sexual gags that would make even the Potato Men blanch: believe me, you'll never look at a glove puppet in the same way again.

Other characters include a trembling greyhound of a New Town woman (Amelia Bullmore); an indefatigably chipper cabaret juror (Deirdre O'Kane); and a host of earnest critics and visiting BBC apparatchiks, not to mention a pricelessly sarky lighting man (Matthew Holness, who no doubt has suffered his fair share on the Fringe, as spoof horror host Garth Marenghi).

Brisk, sombre and at moments unexpectedly affecting, Festival has a little of Mike Leigh and quite a lot of Christopher Guest's ensemble comedies (Best In Show, A Mighty Wind). Most of all, though - as you see in Daniel Cohen's bustling hand-held camerawork - this is comedy in a Robert Altman vein: "Nashville on the Fringe", as Griffin pitched it.

The finale, set at the big awards ceremony, features an act of character assassination every bit as shocking as the bullet shot at the end of Nashville. Festival is a treat - and funnier than any comedy you're likely to see on the Fringe this summer.

j.romney@independent.co.uk