As lead singer and songwriter for The National, Matt Berninger has become a rock star. With the band, which is known for thoughtful, melancholy indie rock, he has developed a flourishing career, supported by strong critics’ responses and an enthusiastic fan base. The National earned a Grammy award just last year for best alternative rock music album for “Sleep Well Beast,” following a nomination in the same category in 2013 for “Trouble Will Find Me.”

But, when friend Erica Schmidt, who is a writer and director, asked Berninger to contribute songs to an adaptation of “Cyrano” she was developing, he began delving into the world of musical theater for the first time.

He says it’s been fun, yes, but plenty challenging, too.

“It’s been an incredible process of quick evolution and pivoting, and it’s water I’ve never swam in before,” he says, from The National’s recent tour stop in Milwaukee.

This musical version of “Cyrano” is being performed through Sept. 9 at Goodspeed Musicals’ Terris Theatre in Chester, and it’s not an exaggeration to say it’s been a much-anticipated production. It broke Goodspeed’s box-office records for first-day ticket sales, thanks, no doubt, to the fact that it stars “Game of Thrones” star Peter Dinklage in the title role. (He is wed to Schmidt.) Portraying the object of Cyrano’s desire, Roxanne, is “Girl on the Train” actress Haley Bennett.

The show features lyrics by Berninger and Carin Besser, who is his wife, with music by brothers Aaron and Bryce Dessner, who are also members of The National.

Berninger has known Dinklage and Schmidt for a few years.

“I met Peter through ‘Game of Thrones’ stuff, and then I think I met Erica at a show, and we just became friends,” he says.

Schmidt came up with the idea for this “Cyrano” and broached the subject with Berninger less than two years ago.

“If I remember right — this is so funny, because I can’t remember — I think the idea was she was doing a play (of ‘Cyrano’) and just maybe wanted to have a few songs, three or four songs, woven into a play in a few specific spots,” he says. Over time, he adds, “More songs just started to bloom, and we shared a ton of music with her we had been working on for just lots of different stuff. Then we started writing new stuff. It just grew and (turned) into a more full musical.”

Berninger had never really written from other perspectives in the way that a musical requires, but he says he got sucked into the lives of these characters, trying to get into their identities and to understand them.

“My wife and I write together, so it was a fun way of just talking about life through the filter or prism of something else,” he says.

He adds with a laugh, “I mean, I’m a goofy-looking dude who was always trying to get the prettiest girl in class or whatever, and ended up having to write songs to do it, so there’s obvious — (Cyrano) is a kindred spirit.”

Berninger talks about how much a performer like Dinklage has to do onstage in a musical — not just sing but dance, remember lines and, as Berninger phrases it, “kill people with a sword and whatnot.”

He says that Dinklage “has got to work so much harder than I do onstage. (In concert), I just stand there with a cocktail in my hand and moan away, and he’s got to dance and climb ramps and stuff.

“And he sounds amazing. … He’s an actor, and the singing part is sort of new for him, too. A lot of people (in this production) are doing things they don’t have 100 percent footing on. That’s why I think it’s been so exciting for all of us.”

When Berninger writes a song, he says, he’s not searching for notes but rather is trying to connect emotionally, and that’s what Dinklage does as an actor.

“So I actually think he was able to slide into the songs maybe even better, easier, quicker than somebody who’s a really trained Broadway singer,” he says.

Finding the way from rock to musicals

It’s true that co-writing songs for a musical was a new venture for Berninger, but the results aren’t too far removed from the sound of The National.

“I think people will totally recognize it as a National musical. It can’t not (be). We couldn’t write a musical that didn’t sound kind of like us trying to make a musical,” he says.

For Berninger, the challenge was to write something that moves the story along, because that’s something he doesn’t have to worry about when writing National numbers. He doesn’t care how clear a narrative is in a National song because he sometimes doesn’t even know what a song is going for until it’s done.

With “Cyrano,” he says, he knows “the songs couldn’t just be meandrous pontifications about myself. They have to move you from somewhere to here, and they had to function and make you understand the character’s emotions.” Learning how to sneak exposition into a love song, for instance, is hard, he says, and all that was new to him.

In fact, Berninger hadn’t really done any theater before this. He was involved a little bit in high school drama but only as a member of the stage crew; He painted some papier-mache for a production of “Brigadoon.” As a kid, he remembers seeing the musical “Annie” (a side note: that show began at Goodspeed), but he didn’t follow theater much after that.

His 9-year-old daughter, though, is a different story.

“She’s doing ‘Alice in Wonderland’ at school, and she’s obsessed with ‘Singin’ in the Rain,’ so that made me also excited about the form, meaning maybe there’s a way I could find my way into this, because there is so much joy and pleasure in that form that I don’t ever get to appreciate or get into,” he says.

For "Cyrano," Berninger would work on his laptop from musical ideas he and the Dessners developed, and he would free associate. He would read the script again and try to inhabit whatever character he was writing for. (The story, pulled from Edmond Rostand’s 1897 “Cyrano de Bergerac,” centers on a poet who, deeply self-conscious about his large nose, ghostwrites love letters from the handsome Christian to the woman that Cyrano, too, loves. Although there are references to Cyrano’s nose in this version, Dinklage doesn’t wear a fake one, and no reference is made to the actor’s height.)

Berninger would come up with a sketch idea, send it to Schmidt, and they would text other ideas back and forth, and Besser would bring in her thoughts. It was, he notes, “a real back and forth.”

Over the past couple of years, there have been short bursts of intense periods in co-writing songs for “Cyrano.” Things moved particularly fast around the times that “Cyrano” had workshops in Manhattan.

“I’d be writing a song in the morning and bring it in, and my wife and I were staying in a hotel in Brooklyn. I would get up early, work, pass it off to her, then The National would have a gig that night somewhere. Then, I’d come home and pick it up and then send something to Erica,” he says.

As for the whole process of working on “Cyrano,” he says with a laugh, “It feels like a big Wes Anderson move, you know? It’s a little Wes Anderson, a little ‘Waiting for Guffman,’ too — it’s all that. … The people have been so fun. It’s also been stressful, for sure. You get everybody in there, and for all the performers and singers especially, the songs are coming from musicians who aren’t used to preparing their work for theater. We’re learning a lot about that. These people are used to these tools to learn music. We’re used to a whole different way of communicating a song to other collaborators — a lot of hanging out with weed (he laughs) and just kind of jamming and looking for stuff.”

He says that instead he and his co-writers have gotten “our ducks in line before we hand a mumble-y sketch over to a bunch of really professional singers. But everybody’s been kind of meeting in the middle and finding a good way of communicating.”

If you go

What: “Cyrano”

Where: The Terris Theatre, 33 North Main St., Chester

When: Runs through Sept. 9; 2 and 7:30 p.m. Wed., 7:30 p.m. Thurs., 8 p.m. Fri., 3 and 8 p.m. Sat., and 2 and 6:30 p.m. Sun. 

Tickets: Start at $49

Contact: (860) 873-8668, goodspeed.org