Kieran Culkin is amazing in ‘A Real Pain’ at Sundance

Making Jesse Eisenberg and Kieran Culkin the leads of a heartwarming movie about family bonds (the non-back-stabbing kind) and self-discovery would seem counter-intuitive.

Culkin has just finished up playing Roman Roy, the cutthroat, foul-mouthed media scion on HBO’s “Succession.” And Eisenberg, even though he’s had a long and varied career, is still best known for his role as subzero Facebook founder Mark Zuckerberg in 2011’s “The Social Network.”

Maybe, you think, these guys would be better off portraying a duo of quirky serial killers.

But thrown together, this awkward pair is magic in “A Real Pain,” an enriching dramedy that had its world premiere Saturday at the Sundance Film Festival. A story of two cousins’ trip to Poland to connect with their late grandma’s roots, it’s one of the best movies of this year’s fest so far.

And it marks a major improvement from Eisenberg’s last go-round as a writer-director, 2022’s “When You Finish Saving The World.” The spark was there, yes, but not quite the execution.

Everything falls into place here. His screenplay for “A Real Pain” — inspired by details of his own life — is funny, aching and wise; the vantages of the European country he captured are steeped in history and tragedy; and he gets a performance out of Culkin that’s every bit as good as his extraordinary turn from “Succession.”

Except, you know, he’s not a complete jackass.

Eisenberg has framed the duo as a tried-and-true comedic combo — a Felix and Oscar from “The Odd Couple” — leading us to think we’re getting “National Lampoon’s Genealogic Vacation.” But the filmmaker subverts our expectations at every kilometer.

David (Eisenberg) is an introverted, responsible, successful tech worker who lives with his wife and child in New York City, while Benji (Culkin) is an unemployed life of the party up in Binghamton who loves pot and can’t control his honesty.

There is, we learn, much more to these two than sit-com tropes and frat house barbs.

They hop on a tour group in Warsaw to visit important sights of Jewish history en route to their grandmother’s childhood home that she fled in 1939.

Also clutching cameras are the recently divorced Californian Marsha (Jennifer Grey), a curious Brooklyn couple (Daniel Oreskes and Liza Sadovy) and a Rwandan-Canadian named Eloge (Kurt Egyiawan) who converted to Judaism after escaping the genocide of his home country.

“A word of warning,” says their British guide James played by Will Sharpe from “The White Lotus.” “This will be a tour about pain.” But, the scholar adds, it’s also “a tour that celebrates a people — the most resilient people.”

Impressive throughout is the way Eisenberg balances reverence for his locations and belly-grabbing comedy, while using those elements to support each other.

When they visit the Warsaw Uprising Monument, honoring Poles who stood up against the Nazis, wild-and-crazy Benji hilariously (but beautifully?) gets the buttoned-up group to pose like they’re also insurgents fighting along with the sculpture.

Later, Eisenberg depicts their solemn walk through the Majdanek concentration camp with the stoicism and straightforwardness it deserves. Words are sparse, and back on the bus a pan across the blood-drained faces that ends on a shattered, crumpled Benji knocks the wind out of you.

A few minutes later comes the funniest line in the movie. The pacing is spot-on.

Making a new European road trip flick comes with some baggage, so to speak, but even as Eisenberg walks the path many other filmmakers have, he doesn’t easily give into contrivance. Surprises abound, and his unique brand of sentimentality isn’t exactly sentimentality as we have come to understand it.

For instance, in “A Real Pain,” somebody getting slapped in the face — hard — brings tears.

Culkin gives viewers the pull-the-fire-alarm quality they love about his untethered personality on “Succession” or during award show speeches in which he muses on his ear hairs. Removed of Machiavellian motives, this would appear to just be him. Benji blurts out totally inappropriate comments that other people could never get away with. Yet, very un-Roman, his default mode is kindness; he always goes in for the hug. Culkin’s brotherly chemistry with Eisenberg, also wonderful, is totally believable.

That he is so good here comes as a relief and another sign that we are living in a Kieransance.

Eisenberg said at the end of his premiere that, with this film, his aim was to explore pain on a smaller scale (a dead grandparent, a flailing life) and on an epic one (the Holocaust). He’s succeeded and, in so doing, made a big punchy film that’s intimate and nuanced at the same time.

In short, a real pleasure.