When the Gotham Award nominations were announced this week, Reed Birney was the sole member of the “Mass” ensemble recognized for his work in the searing drama about two couples grappling with the aftershocks of a school shooting. Some prognosticators were surprised that Birney and not Ann Dowd or Martha Plimpton, who have more emotional, galvanic moments in the film, made the cut for his pared down and minimal performance. But then they may have failed to recognize the shadings that Birney gives his character, Richard, and the moments of intense feeling that break through his facade as he grapples with the fact that his son was a mass murderer. It’s a master class in repression that is devastating to watch and a tribute to Birney’s talent that he’s able to make the audience care for the brisk and business-like father of a killer.

“I’m a WASP and I think Richard’s a WASP,” says Birney. “In WASP culture you don’t talk about your feelings and you don’t talk about personal things. You don’t dwell on things. Richard has taken this to the nth degree where he thinks, yes my son did this terrible thing, but I’m not going to let it ruin my life, which of course it has. He’s trying to hold on so desperately to whatever shred of normality he knew before and it’s not working.”

The low-budget film was a labor of love for Birney and his cast mates, who shot it on an intimate set in Idaho. Most of their scenes find them sitting around the table in a church basement as the cycle through feelings of guilt and anger, searching desperately for a way to make sense of senseless violence. “Mass” marks the feature directing debut of Fran Kranz, an actor turned filmmaker who Birney, the Tony Award-winning star of Broadway’s “The Humans,” knew from theater circles.

“I’d been to see Fran in plays, he’d been to see me in plays, but we hadn’t worked together,” says Birney. “One day in October of 2018, I got an email from him saying, ‘I’ve written this thing and I don’t know if it’s any good. I wrote it with you in mind. I’d be thrilled if you’d take a look at it.'”

Birney approached the script with some trepidation, but as he read it, he saw the possibilities. Kranz had managed to make a horrifying premise deeply human, even optimistic at points. Birney wrote him back saying, “I will go anywhere to do this with you.”

Kranz wrote it as a screenplay, but briefly considered doing it as a play, before deciding that it would, indeed, work best as a movie.

“If it were a play it would be a different animal. In a play you couldn’t have people sitting at the table for 95 minutes. You’d have to find reasons for them to get up and move around the room,” says Birney. “It works better because the camera can come in and you can see their thoughts.”

Birney said he connected to the story as a parent. Every time there’s a school shooting, he would think about the lives shattered by the experience. How, he wondered, does someone recover from that kind of trauma. To prepare for the role he read a New Yorker profile on Peter Lanza, the father of Sandy Hook killer Adam Lanza, and tapped into those feelings that inevitably bubble up whenever there’s another mass murder.

“It’s not a movie about gun control, it’s not even about what happened in that school,” says Birney. “It’s really a movie about how do we connect as people through our pain and our rage and our sadness. It’s about connecting. Everybody has stuff they want to be forgiven for. Everybody has rage and hate that they carry with them.”

Birney has made a name for himself as a consummate theater actor, appearing on and off Broadway in shows such as “Casa Valentina,” “Man from Nebraska” and ” Circle Mirror Transformation.” But he’s shifted his focus to film and television in recent years, having arcs on the likes of “House of Cards” and appearing in “The Hunt” and “The 40-Year Old Version.”

“I’ve done ten million plays and I haven’t done as many films and television shows,” says Birney. “I’m very much focused on doing film work. It’s different to be in a real place. In movies if you cross a street, you’re really crossing a street.”

Last summer, Birney did make time for some stage work, appearing alongside his son Ephraim in “Chester Bailey,” a two-hander they performed at Barrington Stage Company in Pittsfield, Massachusetts. They’d like to take it to New York, but there’s a crush of new shows that are vying for space as theaters reopen after COVID lockdowns. Birney seems content to wait a while, noting that one of those productions, “Aladdin,” recently had to shut down when there was a breakthrough outbreak of coronavirus.

“I don’t think we’re ready to go back honestly,” he says. “Those Broadway theater seats were too close to begin with. I’m not in a big hurry to go back and sit shoulder to shoulder with people I don’t know. When you look at ‘Aladdin,’ I think that’s going to happen more and more.”

Plus, movie work is keeping him plenty busy. Next up is “The Menu,” a dark comedy that finds him appearing alongside Anya Taylor-Joy and Ralph Fiennes.

“It’s a modern-day Agatha Christie story in which Ralph has invited a dozen people to come for the meal of a lifetime and they get there and he’s got an agenda and hijinks ensue,” says Birney. “It’s very Altman-esque.”

There are some strange similarities with Birney’s current major film release.

“My character is named Richard like in ‘Mass’ and I’m sitting at a table for two hours,” says Birney. “People are going to think I don’t have legs.”