I walked out of the screening of Stuart Murdoch’s new (self-described) ‘pop musical’ God Help The Girl unsure of what it wanted to be, and thus of whether or not it got there. A visually sumptuous, alternately naïve and knowing coming-of-age narrative set in a Glasgow rendered rich and lambent in Super 16 MM, God Help The Girl tells a familiar tale of teenage disaffection, discovery, and eventual self-realisation through friendship, sex, and music. The Belle & Sebastian frontman’s first foray into film has its origins in a 2009 soundtrack project of the same name, in which he recruited a range of female vocalists to sing tales of innocence and experience backed by his own band. Murdoch has now tried to sculpt this concept into a feature length (and - it has to be said - at 112 minutes, just way too long) musical paean to those narrative fixations of his: restless adolescence, the clumsy entanglements of the heart, and an endemic wry romanticism which serves as the optic through which the scuzzy city scenery glows.

In many ways it’s a promising proposition – Murdoch’s proclivity for deftly handled narrative songwriting, and the off-kilter slanted observationalism which colours so much of his lyrical storytelling, feels in many ways a shoe-in for the basis of an indie-pop musical. However, there is a sense in which God Help The Girl misses the trick from the offset. Unable to either give itself up to the hyper-reality of the musical format, which would have imbued the sentimentality and cloyingness of the film with an appealing 'yeah – and?' quality, nor to commit to an exploration of the more subtle, gritty, and skewed perspectives which sporadically peer out, God Help The Girl, for all its exuberance and colour, somehow falls deflatingly flat. Which is a shame, because there are some real treats nestling in there among the irritants.

Several of those can be found in the casting. Pleasingly dry and oddly beautiful lead Emily Browning plays Eve, an ostensibly complex character who at the start of the film is suffering from depression, and, we subsequently infer, an eating disorder serious enough to warrant institutionalising. Sneaking out of said institution one night and heading to iconic Glasgow venue Barrowlands, Eve’s bundle of dissatisfactions soon collides headfirst with those of awkward charmer James (Olly Alexander), who takes her under his wing in an impulse of attraction which swiftly – predictably - morphs into one of mooning adoration and unrequited love. Joined by the loyal and bland Cassie (Hannah Murray), the three decide to form a band; an enterprise which loosely structures the rest of the film, gesturing as it does at the redemptive powers of artistic collaboration via several ponderous scenes of reflecting on pop culture and kayaking up Glasgow rivers.

Despite the occasional clunkiness of the script, and a pacing so desultory even the characters’ eyes seem to occasionally glaze over, Murdoch coaxes some genuine sparkle and chemistry out of his three leads – Alexander’s performance in particular threatens to arrive at moments of genuinely engaging pathos and humour, and Browning’s Eve glints magnetically with the promise of greater depths: there’s a scene in a bathtub (no, not that kind of scene) which is beautifully pitched and resonant and speaks to all the places this film could have gone but doesn’t.

Tellingly, the city of Glasgow reverberates with as much if not more vivacity than the characters it is peopled with here; the evident thought that has gone into the screenplay and subsequent cinematography in this regard being one of the saving graces of the film. Historically, popular musicals – from Oklahoma through Bye Bye Birdie, Show Boat, and West Side Story - have always invested locality with considerable meaning and presence, and Murdoch’s film is no exception. Cinematographer Giles Nuttgens is as equally in love with the charismatic face of Glasgow as he is Browning’s, affording an effective translation of the hard wet summer skies of the city into a series of sporadically evocative tableaux, against which the pointedly off-beat indie-chic of the protagonists’ attire sheds much of its contrivance, or at least our registering of it. Here as elsewhere, God Help The Girl strains for a quality of highly-stylised artistry which would have transformed the film had they really committed to it; but again, there is a greediness to the film which results in attenuation. God Help The Girl simultaneously strives for abstraction whilst insisting it drinks at the kitchen sink, leaving us somewhere between a puddle and a rainbow.

That said, the musical sequences do afford many treacly satisfying moments; ‘I’ll Have to Dance with Cassie’, in which Eve toyingly settles for a turn around the hall with her girlfriend in the absence of “a lover with the candour of a friend” is a set-piece which suddenly – and pleasingly - brings Once More With Feeling – the unfalteringly brilliant all-musical episode of Buffy to mind; but it’s a comparison which flags up just how sharp and deftly-handled Whedon’s 45 minute musical excursion is, when compared to Murdoch’s nearly-two-hour long, frustratingly insubstantial offering. God Help The Girl shows its hand with musical scenes which hover persistently at a point of potency, mining the poetic qualities of suburban swimming pools and rehearsal studios as backdrops for melodic articulations of conviction and self-distrust: but, frustratingly, despite flourishes of grabbing the reins, it lets them go slack time and again.

The Buffy comparison is, perhaps, unfair, but it is one that nonetheless hints at the problem here. God Help The Girl doesn’t really know what it is, which is not always a bad thing, but becomes one when it chases so many ideas down without catching up with any of them. Despite its flirting with the darker corners of the story it wants to tell, God Help The Girl’s dalliance with them ultimately feels tokenistic and shoehorned in; depression and extreme body dysmorphia diluted down into a plot device which didn’t really need to be there in the first place, countered with self-conscious ruminations on whimsy and cliché which ultimately lead to hollowness. There’s a lot of promise in God Help The Girl, and an inkling that in a different vehicle that promise would – and perhaps will – be fulfilled; in the end, there’s just about enough here to keep me on the lookout.