Set in the heady days of 1968, four young, talented singers from a remote Aboriginal mission, are discovered by an unlikely talent scout. Plucked from obscurity and branded as Australia’s answer to The Supremes, The Sapphires grasp the chance of a lifetime when they’re offered their first real gig – entertaining the troops in Vietnam. For the girls, a whole new world of sex, war, politics and soul opens before them.

Good times rule in Wayne Blair’s soulful adaptation.

CANNES FILM FESTIVAL: Sunshiny effervescence dominates Wayne Blair's '60s-set parable of self-determination, The Sapphires – a real-life tale of a group of soul sisters (and their cousin) who sang their way from an outback mission to an entertainment tour of duty during the Vietnam War.

In opening scenes, the lively trio of Gail (Deborah Mailman), Diana (Jessica Mauboy) and Cynthia (Miranda Tapsell) are in a flap about getting to the upcoming pub talent quest. A quick musical interlude with their mum (Kylie Belling) highlights their natural harmonies, before the girls' rendition of Merle Haggard's 'Today I Started Loving You Again' blows the tone-deaf opposition out of the water. When the bigoted judges fix the prize against them, they storm out, along with boozy Irish talent quest host (Chris O'Dowd), who has an ear for raw talent.

Directly outside the pub, ambitious Julie produces a classified ad calling for wartime entertainers and, in a matter of minutes, persuasive charmer Dave secures the girls both an interstate audition, and the approval of their strict parents. It's one of several 'just go with it' moments of implausible plot shorthand in The Sapphires, as Blair races through the foundational aspects of the girls' career timeline.

In Melbourne, they call on an estranged cousin, Kay (Shari Sebbens), their erstwhile singing partner until she was forcibly removed from the mission and subsequently raised white. Kay gets the shock of her life when her long-lost koori cousins rock up in the middle of a hoity toity Tupperware party, but her family ties win out, and she signs on to complete the ensemble.

In grooming the girls for stardom, Dave weans them off their beloved Country and switches them on to the bloodbeat of Soul (with a very funny precis of fundamental difference between the genres), and in very short order, they've gotten the nod for a tour of duty and have landed in Saigon.

Their rendition of Linda Lyndell's 'What A Man' gets a bar of G.I.s on their feet in their first gig in Saigon, and the rapturous response to diva Diana's phenomenal voice solidifies The Sapphires' place on the tour.

From the seedy bars of Saigon, their booker whisks them on a tour through real combat zones, to escalating audience sizes and proportionate degrees of risk. It's no spoiler to say that on the course of the trip, some of The Sapphires find love, and all of them find 'themselves'.

Along the way, direct parallels are drawn between black America's civil rights battles of the '60s, and indigenous Australia's ongoing struggle for R-E-S-P-E-C-T, culminating in a performance on the day of Martin Luther King's murder, after singing a Yorta Yorta harmony down the phone line to mum.

Blair cites The Colour Purple as inspiration for the stylised warmth emanating from the girls' home, in a clear break from traditionally bleak depictions of mission life. The sun-drenched tranquility of their family home underscores the girls' core sense of belonging - and how... As depicted in The Sapphires, the Cummeragunja Mission could well be the happiest place on earth.

Cinematography by Warwick Thornton is upbeat; it's saturated brights all the way, and production designer Melinda Doring clearly had a ball with the colour-popping period retro. Full marks to the sound team, led by supervisor Andrew Plain and music producer Bry Jones (of The Rockmelons fame), for maximising the impact of songs from the Motown, Stax and Atlantic Records catalogues.

The screenplay is by Tony Briggs, son of one of the original Sapphires, Beverly Briggs, in collaboration with Goalpost Pictures' Keith Thompson (Clubland). It's an adaptation of Briggs' own stage play, in which Mailman and Blair both appeared. (Blair also has a brief cameo in his film.) At times The Sapphires wears its theatrical origins on its sleeve, with many scenes building to a crescendo of imaginary applause.

The film works best in the musical numbers and off stage, when focussed on the group dynamic. As the most experienced member of the cast, it falls to Mailman's Gail as the 'Mumma bear', to experience the biggest arc, which she does ably.

Where it falters is with several scenes that end too abruptly, and with flat bits that rely on O'Dowd's lackadaisical charm to propel them to a punchline. The aggressively upbeat tone doesn't gel with the gear-changes that draw upon the wider political and social upheaval of the period.

The Sapphires got a 10-minute ovation when it premiered out of competition in a prestigious Saturday slot here in Cannes, and word through the grapevine (where else?) has been building on it, ever since The Weinstein Company picked it up for North American release.

" 'Aboriginal Dreamgirls'. Who's not gonna love thaaat?," I overheard an American-accented festival goer exclaim into his mobile phone on the way into the theatre, before the film had even spooled. "C'mon!"

I sat through the end credits, and so missed my chance to see how that gent would answer his own question. I would contend that a more accurate pithy appraisal is 'The Commitments-meets-Dreamgirls, with a dash of Good Morning Vietnam'. Its unbridled enthusiasm is sure to register with audiences when it opens the Melbourne International Film Festival on August 2 before going into general release the week after. There's much to love, lots to like... and enough roof-lifting musical numbers to make up for the dodgy bits.

Of all the actors in The Sapphires, Mauboy is certain to fare the best; the music numbers are built around her powerhouse pipes, and it'll help the film's international marketability that the singer's own Idol origins echo those of Dreamgirl Jennifer Hudson.