Broods, 2014
Capitol Records

Prior to the release of their debut album, the pop group will open for Sam Smith across North America.

Much of Broods' music possesses a quiet vulnerability, with singer Georgia Nott's delicate voice lilting over the twitching rhythms and threatening to evaporate altogether. At the New Zealand duo's live shows, however, Nott is anything but gentle: she grooves along with her 22-year-old brother Caleb Nott's drum pad thwacking, often bouncing around her stage (sometimes in leather pants!) and sporting some haphazardly constructed dance moves instead of standing still behind her keyboard. On Broods' debut EP, the 20-year-old singer sounds fragile and timid; onstage, she is spunky, boisterous and ready to convert skeptics into believers.

"When we first started performing, we were shit-scared, and concentrating on not fucking it up, basically," Georgia Nott tells Billboard. "We started performing with other bands like [NYC dance duo] ASTR. That girl Zoe is incredible -- she is the most badass person on stage. I was like, 'Holy shit, I need to step up my game.' … I don't know what I'm doing half the time when I'm doing that. I'm concentrating on what I'm singing and what I'm saying, but my body… it's a subconscious thing. And the bigger the stage, the bigger the moves."

"Bigger" is a good way to describe the sound of Broods' debut album, Evergreen, due out this fall on Capitol Records. The brother-sister duo's self-titled debut EP, released in February, included six songs of pristinely icy indie-pop, but Evergreen finds Caleb Nott tinkering with more expansive arrangements and his sister attacking meatier choruses with apparent confidence.

Is Broods New Zealand's Next Pop Wonder?

The Lorde comparisons will be inevitable, since Broods are from New Zealand and worked on the entirety of Evergreen with producer Joel Little, who helmed all of Lorde's debut album, Pure Heroine. But with the songs on Evergreen, Broods sound like they're prepared to make a unique mark on U.S. listeners.

"It definitely covers all the bases of who we are," says Georgia of the upcoming album. "We've got all the upbeat songs that we love to play onstage, and then we've got the sad songs that we love to listen to in our rooms."

After forming the project in early 2013 with little hope of making an impact outside of New Zealand, Broods earned unexpected acclaim on stateside pop blogs with the release of debut single "Bridges" last October. Produced by Little and released during the height of Lorde's "Royals" run on the Hot 100 chart, "Bridges" earned over 200,000 YouTube views in its first week of release, and led to a deal with Capitol in the U.S. and Polydor in the U.K. in early December ("Bridges" has sold 56,000 downloads to date, according to Nielsen SoundScan).

For the Nott siblings, 2014 has been a year of constant journeys from New Zealand to America -- "Travel takes its toll," Caleb says while yawning -- and growing closer as brother and sister while the makeshift duo sets up for a mainstream look. "We went straight from living in the same household to flatting together, and then this," says Georgia. "It's not anything out of the blue -- it's pretty normal for us, and it keeps familiarity everywhere you go. There's a bit of home everywhere."

Lorde Talks 'Mockingjay,' New Music at Lollapalooza: Full Interview

And in one instance, the Notts brought even more of home into the studio: the duo's 18-year-old sister, Olivia, contributes vocals on the album track "Medicine." "We flew her up, and it was like a surprise," says Georgia. "She's really pedantic and gets worried about stuff, and she made me sit behind her in the booth while she was recording, and she would turn straight around after every take and be like, 'Was that okay? How was that?'"

After the Broods EP's six tracks were culled from a year's worth of writing and released in February, Evergreen was written and recorded in just five weeks this spring, with Caleb and Georgia rapidly bouncing ideas off of one another. "I'm abstract in lyric-writing, and Georgia is very literal," explains Caleb. Meanwhile, Little worked closely with the duo on the album, and Evergreen will be his first major project after winning a song of the year Grammy for "Royals."

The Notts say that they've spent hours goofing around with Little and watching funny YouTube videos with him on lunch breaks. Is he any cockier about his production abilities since Lorde became an international star? "He tries to be!" Georgia says with a laugh. "He's got these two adorable girls, and he tells us these cute-ass stories about him and his family, and it's like, 'You will never be a badass.'"

Caleb adds, "Sometimes we'll be like, 'Joel, can we try this?' And he'll try to be a dick and be like, 'See that Grammy over there? Do you have one?' He's super sarcastic."

Last month, Broods released the music video for "Mother & Father," the lead single from Evergreen, and made their late night television debut on Late Night With Seth Meyers on July 16. A spot on Sam Smith's North American tour will kick off on Sept. 15 in Boston, and gives the duo a chance to perform in theaters before the release of its debut album.

"A year ago, we were still working on the EP," says Caleb. "We didn't actually know whether we were going to be anything, or if anyone was going to care."

"Now, you have to make sure you have all your shit together," adds his sister. "At the moment we're trying to balance absorbing it, doing what we need to do and keep the momentum going."