What explosion? Richard Roundtree and June Squibb walk away from this conflagration unfazed in "Thelma." Courtesy Magnolia Pictures

Can you make a thriller with a 93-year-old main character? Maybe it’s not as difficult as we think. Sure, a nonagenarian actor is unlikely to run down rooftops like Tom Cruise, but the editing tricks of cinema can make that actor appear to drive a car, fire a gun, or sneak into a bad guy’s lair. More geriatric than generic, the comic thriller Thelma is closer to Lucky Grandma than it is to Hot Fuzz, but its sunny disposition makes this film worth appreciating on its own.

Our title character is Thelma Post (June Squibb), a recently widowed woman in southern California. One afternoon, she gets a panicked phone call from someone claiming to be her 20-something grandson Danny (Fred Hechinger), saying he has a broken nose after an accident and in urgent need of cash. On this person’s instructions, she mails $10,000 cash to a P.O. Box in Van Nuys. Danny turns out to be fine, and Thelma can stand the financial loss, but when she recovers the number of the P.O. Box where she mailed the cash, she decides to track down her money and the people who took it from her. Partnering her is Ben (Richard Roundtree), a friend in a nursing home whose motorized scooter she needs to borrow.

First-time writer-director Josh Margolin has a fun time playing with the tropes of action movies — we first see Thelma watching Cruise run in a Mission: Impossible movie and marveling at his athleticism at his age. Thelma and Ben walk away from an explosion without reacting, because it turns out they can’t hear the blast. Our elderly heroes aren’t very tech savvy, but they improvise electronic listening devices by hooking up their smartphones to their hearing aids. When Thelma’s daughter and son-in-law (Parker Posey and Clark Gregg) try to track her, she throws off their pursuit by activating her Lifeline bracelet and throwing it over a chain-link fence, since scaling it is out of the question. Then, too, there’s a funny running gag with Ben’s nursing home roommate (David Giuliani), who initially appears catatonic but may be more aware than he lets on.

FWW BTH 300x250

The tension between Thelma and Ben makes a fine backbone for the film, as her determination to see this through herself runs up against his insistence that a 90-year-old might need some help chasing down bad guys. This is the last role for the late Roundtree, and it is a lovely way for John Shaft to go out, but he doesn’t steal the spotlight from Squibb, who has built a highly varied film career that only started after she turned 60. She conveys both Thelma’s childlike wonder and the fire that drives her to ride across town in a motorized scooter to get her money back. (By the way, Margolin based the role on his own grandmother, who is still alive and about to turn 104 as of this writing. The film shows some footage of the real Thelma.) The performances and the sharpness of Margolin’s writing do more than keep this film from turning into goop. They make this an oddity that’s utterly charming and memorable.

Starring June Squibb and Richard Roundtree. Written and directed by Josh Margolin. Rated PG-13.