In late September, the actor Oscar Isaac stood onstage at Town Hall in New York and looked shell-shocked by what was unfolding around him. He was the small-print name on a concert bill that featured legends, from Joan Baez and Elvis Costello to Patti Smith and Jack White.
They had all assembled for “Another Day/Another Time,” a high-profile event celebrating the music of “Inside Llewyn Davis” (an edited version of the concert began airing on Showtime on Friday). There was Isaac, the film’s star, visibly nervous and beautifully fingerpicking an acoustic guitar and singing “Hang Me, Oh Hang Me,” an old folk song that starts and closes the movie.
“I was terrified,” Isaac says several weeks later during an interview over tea at the Ritz-Carlton in Boston. “It was completely surreal and a little humiliating. I always feel a little humiliated after I play music live.”
That’s an astonishing admission from an actor whose latest role hinges on his chops as an intuitive musician. Isaac plays the titular character of “Inside Llewyn Davis,” the new film by brothers Joel and Ethan Coen, which opens in the Boston area on Friday after a wave of early acclaim. It’s a fictional account of a folk singer, loosely inspired by the late, great Dave Van Ronk, navigating the Greenwich Village music scene in the early 1960s.
Isaac was already a musician when he got his start as an actor. Born in Guatemala and raised in Miami, he had played guitar and sang in a now-defunct ska band called the Blinking Underdogs. (He seems more than a little embarrassed when reminded of this, but hey, it was the mid-’90s.) His latest band is an indie-rock duo named NightLab based in Brooklyn, where Isaac lives.
“Inside Llewyn Davis,” though, required something new of him, as both an actor and a musician: faith in subtlety. His performance is staggering, but it’s also intimate and never showy. He keeps Llewyn at a perpetual simmer even when the world around him is closing in.
“I could really chew some scenery sometimes, definitely as someone who grew up classically trained in the theater,” Isaac says. “There would be times when I would be tempted to break something or do something crazy in this film. But when I would think about that, it would immediately feel false. That’s not who this guy is.
‘I learned a bunch of [Dave Van Ronk’s] songs, but I didn’t try to sing them like him.’
“This is about telling the story as simply as possible, and the cameras were always right here [gestures toward his face]. There was no need for expression. It was about really feeling the circumstances and hitting the rhythm of the speech and the physicality of letting all that come through.”
He credits T Bone Burnett, the film’s executive music producer who has previously worked with the Coens (most notably on “O Brother, Where Art Thou?”), with giving him some sage advice early on. Burnett told him to play the music as if he were at home on his couch, which is ultimately how he approached every aspect of the role.
“I talked to Oscar about backing off, keeping the lid on the pot,” Burnett says from his office in Los Angeles. “That’s the tendency a lot of singers have — they try to project themselves, and Oscar didn’t need to do that because the camera was going to be really close to him. [Our approach] was: no attack, all tone. Sing softly and we’re all going to lean in and turn it up.”
At 33, Isaac is far removed from the era of music that the film captures, but he had experienced some of it through his parents.
“I grew up listening to Bob Dylan, particularly ‘Saved’ [the second album in Dylan’s so-called ‘Christian trilogy’] because I grew up in an evangelical household,” Isaac says. “But I wasn’t really aware of the pre-Dylan folk scene other than hearing a little bit of Woody Guthrie and Pete Seeger.”
He didn’t know Van Ronk’s work at all but deeply connected to it once he delved into his catalog, which is a beguiling mix of folk, blues, and jazz. By happenstance, Isaac met someone who used to play with Van Ronk and he gave Isaac some guitar lessons in Van Ronk’s style. He remembers being awestruck by the piercing quality of Van Ronk’s raspy voice, especially a video of him performing “Candy Man,” on which “he sounded like a crackhead freaking out in an alley.”
The parallels between Davis and Van Ronk shouldn’t be overstated; the film isn’t a biopic or even all that concerned with Van Ronk’s story. That was partly by design, but also out of necessity, says Isaac.
“Once they decided to cast me, obviously the Dave Van Ronk thing was out the window. He was 6-foot-4 and 300 pounds, and I’m not that,” he says with a laugh. “I learned a bunch of his songs, but I didn’t try to sing them like him. I tried to do his phrasing and his fingerpicking style, even the way he rested his hand on the guitar. So the fact that I’m not Dave Van Ronk, that I don’t sing or look like him, allowed me to use him more as an inspiration.”
Even though he’s been acting for more than a decade, with roles in films such as “Drive,” “Davis” gives Isaac a chance to burrow deep into a nuanced character that’s neither lovable nor loathsome. He’s a little of both, actually, and the film has a cruel way of saddling Davis with every hardship and stroke of bad luck imaginable.
At a Q&A session after an advance screening at the Brattle Theatre last month, Isaac joked with the audience that he once asked the Coens if they were making “The Passion of the Folk Artist,” a reference to Mel Gibson’s grueling “The Passion of the Christ.”
“He never gets a moment of respite,” Isaac says of Davis, “but that’s [expletive] life, man.”
Isaac considers the Coen brothers his favorite filmmakers, and has been known to play their movies on a loop, but says there’s a vast difference between watching their work and being a part of it.
“It shouldn’t have been a surprise, but there’s just a complete lack of vanity and pretension when it comes to working with them,” he says. “I was surprised by how open they are as people and artists and how they think about art and music.”
They gave Isaac direction, of course, but he came to the project with his own thoughts on what he wanted to accomplish as Llewyn Davis.
“Before we started shooting, I thought, ‘What is he going to sound like?,’ ” Isaac says. “If one of my favorite singers got cast in a role, I think I would want to hear their voice, because that’s what I love about them. So I wanted to have a mix: let my voice as a musician come through and find that brackish water in between Llewyn’s circumstances and then find that middle ground.”James Reed can be reached at firstname.lastname@example.org. Follow him on Twitter @GlobeJamesReed.