NEW YORK, NY.- Of all the juke joints in all the towns in all the South, Amy had to walk into Paul’s.

OK, yes, he invited her. A musician with a touch of fame, whom he’s known since she was a child, she’s stopping in for a visit on a break from her solo tour.

For Lila, the frontwoman of the local band that’s playing the bar that night, the world shifts permanently when Amy glides in, trailing all the glamour and cool of a life so much bolder than anything Lila has ever lived.

“Great set,” Amy tells her afterward. And when Lila bashfully shrugs off the compliment, Amy repeats it. “No, really — great set,” she says, her words unambiguously flirtatious. The chemistry between these two is instant, and profound. As soon as they sing together, so is the harmony.

“The Lonely Few,” the achingly romantic, softly sexy, genuinely rocking new musical by Rachel Bonds (“Jonah”) and Zoe Sarnak at MCC Theater, is Lila and Amy’s love story. The telling of it gives us more of Lila’s world than of Amy’s, though — the same way that the 1999 rom-com “Notting Hill” is grounded more in the world of the ordinary bookseller than of the movie star who wanders in and claims his heart.

Meticulously directed by Trip Cullman and Ellenore Scott, “The Lonely Few” is beautifully cast, and it has an absolute ace in its Lila: Lauren Patten, bringing the full-voiced ferocity that she unleashed in “Jagged Little Pill” — and won a Tony Award for — and the endearing awkwardness that she lent to “The Wolves,” alongside a vulnerability that could just about break you.

In Lila’s tiny Kentucky hometown, music-making is the passion she gets up to when she isn’t working her grocery store job with her bassist and best friend, Dylan (Damon Daunno), or keeping an anxious eye on her brother, Adam (Peter Mark Kendall), whose drinking is out of control.

Her life is gritty and messy and small. Once Amy (Taylor Iman Jones) comes along, Lila is a little ashamed of that, and of her inability to escape to something better — maybe in a place where the fact of her sexuality isn’t met with averted eyes.

“God, I wouldn’t be able to breathe,” Amy says, though of course she recognizes the feeling. Her songwriting hit is a wistful breakup tune called “She,” about her ex-wife, that made it big only when a man recorded it.

Amy’s tour, as it happens, is on pause; her opening act bailed, and she needs to find a new one. Sensing talent as well as a spark, she enlists Lila and her band, the Lonely Few — which also includes Paul (Thomas Silcott), on drums, and JJ (Helen J Shen), on keyboard — to join her for the rest of the tour.

On the road, romance ensues, and so do family complications: Lila’s fretful guilt as Adam spirals without her, still grieving their mother’s death; Amy’s enduring anger that when Paul — the drummer who was her stepdad long ago — left her alcoholic mother, back in New Orleans, he left her, too.

With a habit of cutting people out of her life, Amy is more of a loner than Lila, but each of them has constructed a carapace. The question is whether they are brave enough to shed them for each other.

This intimate, tightly woven musical envelops the audience: with Sibyl Wickersheimer’s wraparound set, which seats some of the crowd in the bar; Adam Honoré’s rock-show lighting, whose beams touch all of us; and the pulse of the songs, which we feel in our bodies — the hard-driving numbers and the quiet ones, too. (Music direction is by Myrna Conn, leading a mostly offstage four-piece band. Sound design, worryingly muddy at first, is by Jonathan Deans and Mike Tracey.)

It might seem for a while that Daunno, a Tony nominee in 2019 for Daniel Fish’s “Oklahoma!” revival, is being squandered in a too-small role. But each of the men gets a number in which he demonstrates the depth of his affection — Dylan and Adam for Lila, Paul for Amy — and each of the actors smashes it. Daunno’s tender reprise of “Waking Up Thirty,” a song about surrendering to dead-end, small-town American life, is devastating.

Seen in an earlier, longer version last year in Los Angeles with a partially different cast, this intermissionless show is constitutionally unsentimental. Ever-present in Bonds’ book and Sarnak’s lyrics is a knowledge of the craggy complexity of life and relationships, and the ways that pain can forestall possibility. Still, “The Lonely Few” puts up a fight against such bleakness.

Over in a corner of the bar is an untouched piano, lurking like a gun in Chekhov. When someone at last sits down to play it, watch out. That’s the cue for one of the scariest human emotions: hope.

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‘The Lonely Few’

Through June 2 at MCC Theater, Manhattan; mcctheater.org. Running time: 1 hour 45 minutes.

This article originally appeared in The New York Times.