In theory, supergroups are a superb idea - put kindred spirits together and, voila, you have an easy sell. In reality, few are truly memorable.

Those that work - one thinks of recent examples such as Canada's rock collective Broken Social Scene, coralling the disparate talents of Feist, Kevin Drew and Emily Haines - work because they achieve a perfect alignment of conviction, chemistry and generosity.

Others are sporadically interesting - the odd combo Monsters Of Folk with Conor Oberst, M. Ward and Jim James of My Morning Jacket or the rock group Atoms For Peace, with input from Radiohead's Thom Yorke, The Red Hot Chili Peppers' Flea and producer Nigel Godrich. They feel like side projects, excuses for pals to hang out and just jam.

Your brow arches a litle when it comes to the latest group, case/lang/veirs. Then you smile, immersed in their sisterhood.

The biggest star here, k.d. lang, e-mailed literary folk-pop gem Laura Veirs and sassy alt-country star Neko Case to form a "folk-punk girl group thing" and, within 30 minutes, both wrote back: "Hell, yes."

In between busy schedules, they wrote original compositions over a two-year period. The results are heartfelt and stellar. Individually, they shine and, together, they radiate warmth and fortitude.

"I just want/I just wanna be here with you/Not bracing for what comes next," Veirs leads the three-part harmonies on I Want To Be Here - a song as much about their commitment to one another as it is about "the underdog, the artist, the unsung", as she has described.

Another track, Song For Judee, is a tribute to 1970s singer-songwriter Judee Sill. You are lulled by the upbeat drums until you hear Veirs' words: "They found you with a needle in your arm/Beloved books strewn round your feet."

The three want to dispel gender stereotypes even as they don't take themselves too seriously. Atomic Number is a mid-tempo rumination on the search for a soulmate with the same atomic number, 42. "I'm not the freckled maid," sings lang, which is followed by Veirs' "I'm not the fair-haired girl" and Case's "I'm not a pail of milk for you to spoil".

The light percussion and gently flecked guitar shore up the perspicacious insights by three accomplished women.

Those who have a weakness for lang's caramel alto can revel in Honey And Smoke, a gorgeous waltz infused with melancholy longing as she witnesses people fawning over her girlfriend. "I watch as they pour honey in your ear," she purrs, as Veirs and Case provide backing "oohs".

It's such ease around one another, earned through hard work and mutual respect, that makes this trio welcome company.