On her first studio recording in three years, singer, songwriter, and multi-instrumentalist Sarah Jarosz completes the musical shift that began on 2013's Build Me Up from Bones.

The earlier album, recorded while finishing her studies at the New England Conservatory of Music, explored songwriting outside the norms of contemporary folk, bluegrass, and country.

Undercurrent finds her defining a music built out from American roots traditions, not bound by them.

She wrote or co-wrote all 11 songs -- a first.

Another is the album's instrumentation.

While her octave mandolin and banjo playing are present, guitar is the dominant instrument here.

Now living in New York, Jarosz surrounds herself with familiar collaborators who include I'm with Her bandmates Sara Watkins and Aoife O'Donovan, Luke Reynolds, Parker Millsap, and Jedd Hughes.

The fingerpicked solo acoustic opener "Early Morning Light" commences with the audacious lyric "All my troubles have just begun...." It's a broken love/leaving song that admits regret and doubt, but ultimately refuses anything but forward motion.

First single "House of Mercy," with its minor-key, rumbling, low-tuned acoustic guitar and arco bass, is a dark, steely Americana blues.

It's a bitter kiss-off tune to a bad-news ex, spiny and forceful: "This house wasn't meant for strangers/But you come knockin' anyway...Underneath that shirt you're wearin'/Strained muscles and a heart of stone...You make me want to be alone...." "Comin' Undone" is a jazzy, rag-tinged shuffle outfitted with a gospelized B-3 and ringing electric six-strings.

Lyrically, it offers more optimism than its melancholy title indicates.

On the solo acoustic "Take Another Turn," in 6/8 time, Jarosz asks "What does it mean to be hungry/Hungry and hunting and wild...Should you talk to yourself a little more/Push right through that closed door." On "Take Me Back," her protagonist desires a return to solace and refuge but also accepts that nothing last forever, as an electric guitar adds poignant solo fills.

"Still Life," driven by a lonesome fiddle, is another broken relationship song.

In it she questions settling for less, but refuses, even though it means leaving a beloved who cannot completely surrender to what love demands.

Though darker than her previous albums, Undercurrent is also more resilient.

Jarosz reaches through her musical and personal histories with vulnerability and willingness.

She comes out on the other side with songs that possess narrative savvy, melodic invention, and a refreshing sense of self-assuredness.