For as much as action thrillers such as “Mission: Impossible” aim to put audiences on the edges of their seats, I have rarely felt secondhand tension as uncomfortable as the opening sequence of “Thelma,” in which an elderly widow falls prey to a phone scammer.

The scene has a pitch-perfect suspense-building lead-in, as we see 93-year-old Thelma (June Squibb) receiving gentle guidance on navigating the internet from her doting 24-year-old grandson Danny (Fred Hechinger), who’s so good to his grandma that we briefly share her initial panic, when she gets a call claiming Danny has gotten into trouble.

Danny and Thelma share an appreciation for Tom Cruise doing his own stunts in the “Mission: Impossible” films, in spite of Cruise entering his 60s. When Thelma overhears her daughter Gail (Parker Posey) and son-in-law Alan (Clark Gregg) wondering aloud whether she needs to move into an assisted living facility, Thelma decides to undertake the seemingly impossible mission of recovering her lost money from the scammer, whose address isn’t far away.

The delightfully novel concept of “Thelma” is that writer-director Josh Margolin filters the everyday infirmities and inconveniences of his protagonist’s advanced age through the lens of popcorn blockbuster clichés, with hurdles such as climbing carpeted stairs, and standing on a bed to reach a high shelf, treated with all the gravity of Tom Cruise’s rooftop speed-runs.

Along the way, Thelma acquires a partner-in-crime in her departed husband’s friend Ben (Richard Roundtree), who moved into assisted living after his own wife died.

While it’s hilarious to see Thelma and Ben use his two-seater electric scooter, and her medical alert bracelet, to evade her worried family, it’s genuinely moving to see how the two seniors are attempting to cope with slowing down; Thelma by doubling down on her stubborn determination, Ben by grudgingly acknowledging his newfound, unwelcome limitations.

John Shaft in the role of Ben is a significant casting choice, since Roundtree’s last onscreen outing as the ultra-masculine Shaft was in 2019, only five years ago. It hits hard when his character expresses his grief and guilt over his loss of power.

The entire cast is as excellent as one would expect, with Posey and Gregg complementing each other flawlessly as an amusingly fussy married couple, whose care for her mother, and their adult son, is authentically heartfelt, if overly attentive.

An unexpected standout is Hechinger as Danny, an insecure man-child who’s actually a surprisingly positive role-model for non-toxic masculinity, because while he’s crippled with self-doubt over what he perceives to be his own lack of useful life skills, he channels those anxieties into caring for his grandmother. He smiles and sits patiently with her as she struggles to operate her computer mouse properly.

Just as Ned Leeds styles himself as “The Guy in the Chair” for Peter Parker, in the Marvel Cinematic Universe’s Spider-Man films, so too does Danny fulfill the “Mission: Impossible” cliché of the tech-savvy voice in our hero’s earpiece (or in Thelma’s case, her smartphone-linked hearing aid). He talks her through her final fraught travails, in order to get back what’s hers.

While other onscreen post-adolescents bask complacently in slacker ruts, what makes Danny endearing is that he earnestly wants to improve himself, even if his emotional growth has likely been stunted by his parents making too much over every little problem in their lives.

Even Danny’s ex-girlfriend Allie — Coral Peña, taking a between-seasons break from being consistently awesome in “For All Mankind” on Apple TV+ — seems to believe in him, almost as much as his loving grandma, as Allie expresses her support for Danny’s aspirations to do (and be) better.

Squibb herself has remained as effortlessly natural a performer as she was when I first noticed her, sharing a screen with Bruce Dern, Will Forte, Bob Odenkirk and Stacy Keach in Alexander Payne’s 2013 comedy-drama “Nebraska.” She is so real as Thelma that I felt a tangible sense of plummeting dread, as she unwittingly fell for the phone scammer’s scheme.

I won’t spoil the last brand-name actor, whom I haven’t yet mentioned, except to note that his role likewise underscores his advanced age, given some of the larger-than-life characters he’s previously played.

It all wraps up with a scaled-down version of the sort of slow-walk away from an explosion that’s obligatory to the genre that “Thelma” is parodying.

Stick it through the closing credits just long enough to catch a fleeting glimpse of the real-life woman who apparently inspired our indefatigable heroine.