The film, which marks Shannon’s feature directorial debut, premieres June 10 at the Tribeca Fest. He wasn’t really looking to make the move behind the camera, but there was something about Brett Neveu’s script that hooked him.

“I wasn’t predisposed to direct a movie,” Shannon says. “I always found it an intimidating proposition. It always looked like a nightmare — all that responsibility. Everyone needing you to sign off on everything. But when I read the script, I could just see it and feel it in my bones. I knew I had to do it, and I worried if someone else did it, they’d just screw it up.”

“When I first wrote the play, I was so angry,” Neveu says. “I was so upset that this had happened. And while that anger is still present, by the time I returned to it, my understanding of grief had changed. I feel like I was able to let the anger go.”

There’s a lot to still be angry about. In the ensuing decades between the stage show and the film, the number of school shootings has grown exponentially, making “Eric Larue” infuriatingly topical. I ask Shannon if he was hoping to make a point about gun violence in America with the movie, and I can sense him tense up.

That’s a state of mind that he shares when it comes to the United States. “I used to get very vitriolic about my feelings about America and say incendiary things about certain events,” he says, his voice softening. “Now, more than anything, I’m just confused. I don’t know if I love or hate this country. I don’t think America makes any sense.”

The production of “Eric Larue” was not immune from the ferocious political debates gripping the country. The movie was initially intended to be shot in Little Rock, but the filmmakers opted to move to North Carolina after Roe v. Wade was overturned and trigger law in Arkansas went into effect banning all abortions, including cases of rape and incest.

“I felt strongly that we needed to move. This insistence on every woman having a baby no matter the circumstances of how they got pregnant. And the disinterest in helping that person once they are brought into the world, it’s all very confusing. I don’t understand why you would mandate that every child be born and not be ready or interested in helping them.”

Eric Larue is a showcase for Greer, who plays a woman trying to figure out how to move on in an insular community still reeling from the carnage her son caused.

She returns to her work in a big box store, where her employer seems unhappy to have her back. She grapples with her failing marriage — her husband (Alexander Skarsgård) has grown increasingly religious and disconnected from his wife. She attempts to meet with the mothers of some of her son’s victims. But a nagging emotional paralysis persists. It’s a major departure for Greer, best known for comedic supporting turns in “Arrested Development” and “27 Dresses.” But it’s one that Shannon knew she could handle, having worked with her on 2017’s “Pottersville,” a Christmas comedy that seems pretty far removed from “Eric Larue.”

“Judy is super smart and very sensitive and has this huge emotional life that’s very present,” says Shannon. “She doesn’t usually get the opportunity to do something like this, so this felt long overdue.”

“I’m kind of curious to see how this one does before I even think about doing another one,” Shannon says. “I don’t have anything in my back pocket.”

Shannon’s acting schedule is full — he’ll reprise his role as General Zod (the guy who did a number on Superman) in this summer’s “The Flash” and will reunite with “Take Shelter” director Jeff Nichols on “The Bikeriders.” But one project that might not be making it to the screen anytime soon is “McCarthy,” a drama that was to see Shannon playing demagogic U.S. Senator Joseph McCarthy under the direction of “The Painted Bird’s” Václav Marhoul.

“That thing has just stalled,” Shannon confesses. “They can’t get the money. It’s a shame, because I really want to work with Václav. This guy is a badass. All he wants to do is make this movie, but the producers can’t get it together.”