Jesse Eisenberg had to throw out his playbook to direct Kieran Culkin in 'A Real Pain'

Jesse Eisenberg had not seen “Succession” when he was writing his new film “A Real Pain," but his sister knew from watching Roman Roy over the years that Kieran Culkin would be perfect

Jesse Eisenberg had not seen “Succession” when he was writing his new film “A Real Pain.” But his sister Hallie Eisenberg knew from years of watching Roman Roy that Kieran Culkin would be perfect.

The film, which premieres at the Sundance Film Festival on Saturday, follows two very mismatched cousins, one anxiety ridden and rule following and the other a more spontaneous spirit, on a trip to Poland. They’re reuniting to see where their late grandmother was from and also explore some Holocaust locations.

Eisenberg had wanted to play the spontaneous one, which was similar to a character he'd played on stage in “The Spoils” in England. But he was gently talked out of it. It was, he realized, a taxing role that might be too much to handle while also directing. And so, Culkin became aspirational.

They’d met previously through their mutual friend Emma Stone, who also produced “A Real Pain,” but he really didn’t know him well. And he’d quickly discover that casting Culkin and directing him, even getting him on set, was a different kind of challenge that he hadn’t expected.

Three weeks before shooting, when Eisenberg was “knee-deep in securing locations,” Culkin told him he was thinking of dropping out. He didn’t drop out, but he also arrived on set only a day before filming, telling Eisenberg simply that he understood the character and that he also works best without blocking.

“I had spent months blocking out the scenes with Polish actors,” Eisenberg said. “Halfway through day one we had to change our plan. And it was completely to the advantage of the movie because Kieran is such a live wire. He’s such a spontaneous actor and he’s so brilliantly funny. To kind of hem him in with my pre-planned shot list would have killed the spontaneity and the energy of the movie.”

It both “flummoxed and elated” his cinematographer who had never worked with an actor who didn’t adhere to marks. But, Eisenberg said, the scenes where they could ditch the dolly and just follow Culkin “sparkled.”

“I love both characters so much,” Eisenberg said. “I suspect audiences will just assume I’m very much like the character I play. But both are people I know. At once I am kind of the nervous person in the room who wishes I can get out of my own head. And on the other hand, I am a performer.”

“A Real Pain,” which is seeking distribution at the festival, is both funny and profound – an odd couple trip and an exploration of ideas of modern pain in the face of historical family traumas.

Eisenberg has been wanting to set a movie in Poland for about 18 years. The first play he’d written was about a self-centered young American who goes to Poland to stay with his cousin, a survivor of the war, to take advantage of a free room in an exotic locale. It was based in part on an experience he’d actually had. On stage, Vanessa Redgrave played his cousin.

“I tried for years to adapt that into a movie, and it was never good,” Eisenberg said.

It took on various iterations too, including one about cousins who are more contemporaries going to Mongolia for Tablet Magazine. But it wasn’t until he saw an advertisement that said “Auschwitz Tour (with lunch)” that the story cracked open.

“I remember thinking, oh, that’s the story. It’s these kind of middle-class trips to the most horrific places on Earth where the interpersonal dynamics of the group could be explored against a backdrop of real historical trauma,” he said “You can explore the dramatic irony of taking one of these trips, but staying in the Radisson Hotel. Seeing Auschwitz during the day and drinking wine at night with your group.”

He enlisted the help of renowned Polish film producer Ewa Puszczynska, who was fresh off “The Zone of Interest,” which would be essential both in legitimizing this American production abroad and in managing logistics for a very complex shoot.

“We are in a different location every day and every location has challenges. We are in airports, on trains, in city centers, at monuments, at a concentration camp. The first feature film to be able to film at this concentration camp,” he said. “It was just this incredibly ambitious production. And thank goodness we had the best producers in the country shepherding it.”

Those in the tour group, led by a character played by “White Lotus” star Will Sharpe, are mostly retired Jewish Americans (Jennifer Grey among them). But Eisenberg also wanted to broaden the story and included a character, Eloge, (Kurt Egyiawan) based on a friend of his who survived the Rwandan genocide and later converted to Judaism in Winnipeg. His hope is that “A Real Pain” speaks to a cross-cultural, universal experience — though he’s also worried that sounds too much like a commercial. What he really wants, though, is for audiences to find it funny.

“It plays lighter than the themes might imply,” he said.

“A Real Pain” is his second as a director, after the mother-son film “When You Finish Saving the World” which premiered at the festival a few years ago. It’s a busy Sundance for Eisenberg. In addition to trying to sell “A Real Pain,” Eisenberg is also starring in “Sasquatch Sunset,” about a family of Sasquatches. And on opening night he presented a tribute award to his friend and oft-co-star Kristen Stewart, who said she hopes that he gets behind the camera more often.

“He been a real reluctant filmmaker. He’s always like, ‘Oh, I could never,’” Stewart said. “I’m like, no, no, you are a born storyteller. And that’s the way that his acting comes across. Like some actors really service other people’s stories. And then some people are writers themselves, even within their acting. Jesse is just like a kind of virtuoso artist.”