There should be a lot to like about Sunshine Cleaning: a promising set-up, very watchable leads in Amy Adams and Emily Blunt, along with the ever-affable Alan Arkin, and a snappy 90-minute running time sounds like it should add up to solidly diverting fare, and at least for its first few reels the film hums along quite nicely. Yet despite these positives, the film never convincingly satisfies, not falling into that typical Sundance trap of over-quirkification, but simply not delivering enough of either story or genuine characterisation to be of much interest.

One of the main problems is the onscreen presence of too many tired archetypes: amiable and well-meaning single mother Rose Lorkoski is a former high school princess whose life has not panned out as successfully as she or her peers might have expected, and now juggles cleaning houses for a living and taking care of her loveable but at times troublesome young son Oscar. Mac the school quarterback she used to date she is now having an affair with behind his wife’s back. Her sister Norah is something of a layabout and still living at home with their father Joe, himself jovial but deluded into pursuing countless Quixotic get-rich-quick schemes.

This could be the backcloth for many an unambitious indie flick, but then comes that interesting premise: Mac, now a police officer, informs Rose that he has heard of the disproportionately high fees paid to companies who come in to clean up crime scenes, and suggests she enter this lucrative market herself. Faced with the prospect of having to fund her son’s apparent need for special schooling as well as financially supporting the other members of her dysfunctional family, Rose embarks on this new venture, enlisting her newly unemployed sister to help her out.

There is fun to be had here with the two sisters learning the ropes of their new trade. Adams and Blunt are both fine actresses, and their chalk and cheese act is the highlight of the film; Amy Adams does her nice-girl-out-of-her-depth schtick with aplomb, her bushy-tailed optimistic disposition severely tested at the sight of blood-splattered shower stalls in maggot-infested hovels. Playing off this, Blunt’s charmingly dry Rose counterpoints with sarcasm and ironic humour, her performance filling out her rather badly-written and ill-conceived character.

The problems, though, begin to pile up. Firstly, while the setup offers much promise, the ideas quickly run out, leaving things to be padded out with numerous unnecessary asides, in particular the scenes with Joe and Oscar whose irrelevance and whimsy highlight the script’s shortcomings. As the ideas dry up, we then skirt dangerously close to Sundance clichés: ‘inspiring’ moments of apparent realisation and transcendence, underscored by noodly acoustic indie music, undoing all of the good work the exposition had done to establish some sort feeling of identity and authenticity.

Other characters and details are then thrown in to advance things – we are, for instance, given the information that the sisters’ mother commited suicide, but it is introduced messily and lacking in the required emotional heft. Elsewhere, Norah’s befriending of a suicide victim’s daughter once again sets up what could be an interesting relationship, but as all to often happens in this film, their interactions swiftly descend into triteness. And like much elsewhere, these are suggestions that Sunshine Cleaning could have been an interesting and entertaining film, but for a little more care and attention to detail.