Before Danielle and Este Haim were riding motorbikes in the sun, catching fish with their bare hands, or making potential suitors weep with heartache, they were Valli Girls. The Los Angeles sisters played guitar and bass, respectively, in the tween-pop quintet that was assembled and signed to major label Columbia in 2004, with 1980s soft-rock linchpin Richard Marx attached as a creative contributor. The results were decidedly mixed: there was the acoustic melodrama of The Sisterhood of the Traveling Pants soundtrack cut "Always There in You", the cruelly ironic "Born to Lead" ("My independent voice will have its say"), and most notoriously, "It's a Hair Thing", the dog whistle-pitched theme song for the short-lived animated TV show "Trollz".

This early group wasn't the beginning of the Haim sisters' musical career—the pair had been performing covers with the rest of their family, including youngest sister Alana, since they were old enough to hold instruments. "We're just ourselves," a 17-year-old Este Haim was quoted as saying in a 2005 press release that touted the Valli Girls' debut album, Valli Nation. That sentiment wasn't entirely true: as a Fader story from earlier this year detailed, musical prodigies Danielle and Este weren't all that into playing songs that they didn't write, so they pulled out of their contract. The family band was christened with the endearingly dorky name Rockinhaim, thereafter shortened to Haim when the sisters decided to strike out on their own in 2006.

So far, the story of Haim has seemed ripe for the type of movie you'd catch playing on VH1 on a Sunday afternoon and Days Are Gone, the trio's outstanding full-length debut, is the latest plot twist. The album arrives just as Haim's impeccably crafted mix of influences—soft rock's incandescent glow, R&B's sensuality, the spiky-yet-polished effervescence of pop-rock—are more fashionable than ever. But Haim weren't just raised on these genres; they were raised to perform them; they may benefit from perfect timing, but they scan as anything but opportunistic.

Since Days Are Gone single and blog-buzz fire-starter "Forever" made the rounds in early 2012, Haim have often been mentioned alongside Fleetwood Mac; critic Ann Powers recently described their sound as an encapsulation of Billboard's Hot 100 singles of 1987, which included the Mac's Tango in the Night single "Little Lies". The comparison is not without merit—much of the dusky, ebullient "Honey & I", one of Days Are Gone's highest highs, sounds as if The Reminder-era Feist fused together the acoustic riffs of "I Don't Want to Know" and "Never Going Back Again". But Haim also channel the best elements of their current peers: Phoenix's compressed pop economics, the cool-handed spaciousness of Arctic Monkeys' recent work, and Spoon's wound-coil precision.

The latter quality is Haim's secret weapon. Along with drummer and L.A. scene fixture Dash Hutton, Haim sound as tight and in-the-pocket as you'd expect from a group of people that have spent most of their lives making music. Simian Mobile Disco's James Ford (Arctic Monkeys, Klaxons) and studio-man-of-the-moment Ariel Rechtshaid (Vampire Weekend, Usher) both receive co-writing and production credits and contribute just the right touches to Haim's sleek, streamlined arrangements. The record's mix is translucent and refreshingly bare-bones, which affords plenty of space for Days Are Gone's many indelible hooks—the twitchy R&B of "If I Could Change Your Mind", "Don't Save Me"'s rollicking bursts of euphoria, the resonant melancholia of closer "Running If You Call My Name"—to work their uncanny magic.

When you hear about the influences and consider just how slick the record can be, you might imagine Haim coming over as faceless. But the band's most unusual quality on Days Are Gone is their ability to absorb inputs and continue to sound distinct. The album's punchy title track was co-written by Jessie Ware, another artist who's made a name replicating the sounds of pop's past, along with Ware's frequent songwriting collaborator Kid Harpoon ("Wildest Moments", "Night Light"); Ware and Harpoon's style is usually easy to pick out, but it's barely felt on "Days Are Gone", as Danielle Haim's staccato delivery pops and locks where Ware's vocals would have crested and swelled. That Haim retain their identity through collaboration speaks to their confidence.

The lyrics on Days Are Gone aren't necessarily built to withstand close analysis; largely, the words function to add a bit of weight to the effortless, feather-light melodies, but Haim do know how to turn a phrase. "The Wire", especially, has some of group's most effective lines, a level-headed act of kiss-off kindness ("I gave it all away/ Just so I could say that/ Well I know that you're gonna be OK anyway") paired with a rolling melody that makes the song one of the most benevolent breakup anthems since Robyn's "Call Your Girlfriend".

Days Are Gone is so polished that Haim could easily be seen as clinical and lifeless, but their lighthearted attitude complements their recording rigor. Whether they're covering Miley Cyrus and Sheryl Crow, making "bass faces", or reuniting Rockinhaim by bringing their own parents on stage for a rendition of "Mustang Sally", Haim come over as affable, playing-to-the-rafters rock stars as well as studio pros. Taken as a whole, the project is a testament to what's most important, and Days Are Gone's divine pleasures suggest that, rock history be damned, family business doesn't always have to be dysfunctional.