PARK CITY, Utah—If Tom Cruise ever retires from action movies, I know a 94-year-old actress more than capable of taking his place.

In what will likely be the most crowd-pleasing movie to play at this year’s Sundance Film Festival—it’s early yet in the fest, but I feel pretty certain—Oscar nominee June Squibb plays the title role in Thelma: a 93-year-old grandmother who plays out her very own version of Mission: Impossible.

Thelma is a widow who lives alone, a creature of routine—needlepoint, watching the news, playing mahjong on her computer—whose days are perked up when her doting 24-year-old grandson Danny (Fred Hechinger) visits. From the first scene, their special bond is evident, a soul-warming treat after spending a day in the Park City cold. Thelma relishes the humor he brings to helping her with “gosh, I’m old” tasks like how to find an email in her inbox, though she resents his insistence that she wear a LifeAlert bracelet—a reminder that her family doesn’t think she can be self-sufficient.

That tension between Thelma asserting her vibrancy and agency, and her family’s concern that she’s a doddering old lady, comes to a head when she falls prey to a phone scam. She gets a call from an unknown number, the person on the other line claiming to be Danny, saying he’s in jail after getting into a car accident. Thelma is beside herself when another person claiming to be Danny’s lawyer calls, insisting that she mail $10,000 to his P.O. Box, otherwise Danny will be in real trouble. (Apparently, this film was not inspired by Real Housewives of Salt Lake City scammer Jen Shah, though it very well could have been.)

Thelma stumbles around the house in a frantic rush, gathering piles of cash from shoe boxes, her mattress, and all the other places she stashed them. She can’t get a hold of her daughter or son-in-law (Clark Gregg and Parker Posey, delivering gorgeously hilarious, neurotic performances), so, with time ticking to save her grandson, she takes a cab to the post office and mails the cash.

When the family finally calls her back and everyone realizes that Danny is fine and Thelma has been swindled, she’s humiliated. She can’t believe there’s nothing the police can do, and finds it preposterous that the fraudsters could have gotten her contact information online from a site like Facebook: “How could Zuckemborg let this happen?” she asks, mispronouncing the Facebook founder’s name. Back at home, she is dejected as she overhears her family whispering about her. Not only do they think it’s not worth finding a way to get the money back, they fear the whole ordeal is a sign that Thelma’s mind is deteriorating and she shouldn’t live alone anymore.

Fueled by shame and outrage, she channels her inner Ethan Hunt. If no one is going to help her, she would get the money back herself—and show that age ain’t nothing but a number when it comes to a woman on a revenge mission.

Squibb’s steely determination is perfect for a movie like this, mined for the type of comedy about “old people” that you might expect. But she and the film subverts those laughs to drive home a touching truth: It’s egregious the extent to which the elderly are discounted, coddled, or made to be invisible. Squibb is a powerful force, hitting every nuance of heartbreak, resolve, and humor as she relishes something entirely rare, if not non-existent: the action comedy with a 94-year-old actress at the center. Her delivery of the line “I didn’t expect to get so old” is an emotional dagger, the heart-wrenching thesis behind the whole film.

In order to pull off this mission, Thelma knows she can’t involve her family. They’d just try to stop her. The issue is, however, that everyone she calls, she learns, is now dead. (“Ruth burned up in a fire pit!” she exclaims about her friend who, well, fell into a fire pit.) She tricks Danny into driving her to a retirement home, where an old friend named Ben (the late, great Richard Roundtree) has an electric scooter that could be her ticket to pulling this revenge heist off.

After lying to Ben that she’d like to test the scooter out, she speeds off with it out of the facility—a senior citizen’s version of a getaway car. Ben chases after, lifting another resident’s scooter to catch up. They basically have their own version of a Tom Cruise movie’s car chase, translated for the nonagenarian set. Eventually, Ben agrees to be her companion: basically, Thelma’s own Louise.

The first order of business is to steal a gun from another one of their old friends, which is a task that requires Thelma to climb a large flight of winding stairs and then stand on a bed to access the gun’s box, a sequence as intense as any action thriller set piece. Their odyssey has all the false starts and last-second triumphs that you’d expect from the genre, all leading to a showdown at a lamp store where the scammers that targeted her are working.

The journey through the store is very Mission: Impossible-coded. Thelma climbs over fallen lamp stands and ducks under low-hanging chandeliers like they’re security laser beams in a bank vault, while Ben whispers navigating instructors to her through her hearing aids that are connected to her phone.

I won’t spoil whether or not Thelma and Ben succeed in getting their money back—though I’m guessing you can predict what happens in a movie like this. What I wasn’t expecting was how poignant the conclusion of their journey would be.

Thelma is a movie with broad jokes about aging that play very well, but it also has a lot to say both about how the elderly are treated by society, even by their closest loved ones, and what it feels like to get older and not recognize your life and your potential anymore. The whole “grandma on a revenge mission” is an entertaining gimmick, but Thelma also works as an industry plea: Center more characters like this as the leads in their own stories.