Tony Montana didn't build his empire after a weekend's charabanging in Aberystwyth. Unlike other drugs, the magic mushroom is largely unrepresented in movies and it'snot to see why. If cocaine is Al Pacino, magic mushrooms would probably be Rhys Ifans. Mushroom munching doesn't generally lead to your boss's wife overdosing spectacularly, FBI helicopters chasing you down the freeway, or free-diving around Edinburgh's sewage system to an Brian Eno / Daniel Lanois soundtrack; altogether, it's a conspicuously un-cinematic high. Compared with a crimson flower-burst sprouting in a syringe, a cable of coke on a gleaming mirror, or even the mighty Camberwell Carrot, how cool is a cup of tea? <br /><br />Just a handful of films have nibbled round the caps, including Performance, Work Is A Four Letter Word and - coyly - Dougal And The Blue Cat (less a whimsical child-friendly distraction, than an escalating series of terrifying derangements), in which Dylan the rabbit complains of feelings of exhaustion after cultivating his "crazy mushrooms".<br /><br />And now Shrooms, the latest addition to this sub-sub genre, in which some American backpackers discover the downside to pigging out on fungi fancies. Tara (Haun) doesn't even take Aspirin - so perhaps isn't ideally suited to fly to the Old Country on a drugs hunt at the invitation of an Irish school friend-turned-mushroom guru called Jake. But "nobody's ever died from taking 'shrooms before," she's reassured, thus guaranteeing they'll be squealing like stuck piglets before the 90 minutes is up. Ireland is a land where schoolgirls riverdance in circles - and that's before our tourists are barely through passport control. It wouldn't surprise you to see a pony in a lift, or a Guinness-swilling pig in a green velvet jerkin carrying two leprechauns under each trotter. Yet once they've left the airport and set up camp in the wild, wild wood, they could be almost anywhere. <br /><br />Jake (Huston, John's grandson, so possibly cast for his distant Celtic roots) turns out to be a supremely punchable Trustafarian tit. "When I was first sent to boarding school I used to get the s*** kicked out of me a lot," he explains, and it's no surprise at all. But the discovery of those happy little mushrooms helped him through those lonely days and nights. "These bad boys with the black nipples are the Death Heads," the cut-price Castaneda points out, while the audience wonders just what the heck kind of accent that is. It's not Irish. More like Joe Strummer circa 1977. "According to the ancient Irish druids," he drawls, "these are a gateway to another dimension," enabling one to commune with the dead, shape-shift, and predict the future. It's true, you can. Five minutes in, you're certain this feeble, derivative blarney (Blair Witch, Cabin Fever and Silent Hill can all be found bobbing away in the broth) will leave you with feelings of profound emptiness.<br /><br />Round the campfire, Jake relates a supposedly real-life ghost story concerning a nearby abandoned borstal that was run by an evil religious order called 'The Black Knights'. After stringing the kids from the rafters and flinging them to slavering hounds, one vengeful tyke spiked their soup bowls with Death Heads one night and carnage ensued. Only a monk and a feral child survived - then went missing. Legend has it, they're still roaming the woods. Nice one, Jake: just the thing to tell a bunch of silly kids with a head full of psychedelics. From here on in, it's business as usual. Bluto the jock gets slaughtered while out 'dogging', shortly after conversing with a talking cow; the rest follow suit. <br /><br />Meanwhile, Tara's witnessing their grisly deaths before they happen - or is she? As she wails, "I overdosed on the heroin of shrooms, I don't know what's real and what's not!" If it's not some malevolent Black Knight or feral dog boy they glimpse tearing through the trees - or do they? - it's a couple of bestial goat-herders wielding axes. Or are they? Look: here's a boy with a sack on his head. Or is there? Somebody just threw a stone in my eye. Or did they? There's no escape from your own mind. Luckily there's an escape from the cinema, just below the psychedelic Exit signs.<br /><br />Yet the real problem at the core of Shrooms is a more fundamental one: there are few ventures more redundant than trying to replicate the inner-world on film (see Shane Meadows' Dead Man's Shoes or Jan Kounen's Peyote-drenched western Blueberry for two of the more convincing efforts). 'Sacred Weeds', a 1998 TV series, encountered similar headaches after getting a bunch of dosed-up students to record their experiences live to digicam. Not being Mexican shaman with direct dialling codes to Mescalito or the Virgin Mary, these guinea-pigs' trips largely depended on the limits of their experience; they were hardly going to return from their controlled brush with salvia divinorum - containing the most powerful hallucinogen known to man - with anything but giggling fits, some musings on oak bark, and what it's like to sit in a tree. (You feel like a big old monkey, apparently.) <br /><br />"The hallucinations are so intense, I might not be able to speak at all," swooned one excitable and, in the event, overly optimistic participant. But with nothing of note to report, and Sacred Weeds' under-cranked and over-cranked cameras affording scant compensation, why bother in the first place? <br /><br />Shrooms also has to make do with the self-same camera tricks to replicate the audio-visual apparitions, and to similarly lackluster effect, while its monotonous over-reliance on sudden, deafening chords pastes over the lack of genuine shocks. That said, one short scene in which Bluto first trips through the woods (in both senses) comes close to capturing the spatial dislocation common to the psychedelic experience, and one wishes the film offered more moments like this one. But as Alan Partridge once opined, "Dere's more to Oireland dan dis."