It’s been a year since Rostam Batmanglij dropped Half-Light, his solo debut album, and he’s back today with his first song since. Is he about to lap his former Vampire Weekend bandmates by putting out two full-length projects before they even release one? That probably won’t happen given that VW’s long-awaited Modern Vampires Of The City follow-up is finally finished, and Rostam has been playing this new one on tour for quite a while now.

The song is called “In A River,” and the title is quite literal. Its lyrics tells the story of Rostam and a romantic partner skinny dipping in a stream. “We are swimming / With no clothes on / In a river in the dark,” he sings. “And I am holding / Onto you, boy / In the faint light of the stars.” In a press release, he explains that it’s the first song he ever wrote on a mandolin and that its recorded was heavily influenced by interaction with audiences on tour.

He continues:

In January we started rehearsing the song for the Half-Light North American Tour and it became a staple of every show. When we came back from that month-long tour I booked time at Vox Studios in Hollywood and jumped into recording the song. At that point we had played it some twenty times in front of twenty different audiences across the country. About halfway through the tour I started bringing the audience into the song and asking them to clap along after that second chorus. I have memories of how those claps sounded, I can still remember how hard they hit in Grand Rapids, Michigan, in a packed theatre with a foot of snow on the ground outside.

When we got in the studio, I knew I wanted to capture the feeling we got when we played it live, so I pulled the audio off a YouTube clip from a few nights prior — in San Francisco — and dropped it in the Pro Tools session. That audio became a road map for how the song should move. The tempo fluctuates widely — kicking up as the drums enter and the violins solo, then settling into a slower groove when we get back to the chorus, finally slowing down even more as the song ends with the 808 bass and vocals. It’s so rare that modern music gets “off the grid” but “In A River” is a hybrid. It’s steady for the first half but then free in tempo from the moment the drums come in.

I often want the songs I produce to be meeting places for organic and electronic sounds — old traditions and new ones. “In A River” is new territory for me because although it’s a studio recording, it’s pulling from one of the oldest traditions in music, a live performance in front of an audience.

Listen below.

Rostam will headline the Fonda Theatre in Hollywood this Friday, 9/14.