Actor June Squibb, 94, made a splash at Seattle International Film Festival

SEATTLE — “I read it and knew immediately that I should do it,” said June Squibb, in town recently as a guest and honoree of the Seattle International Film Festival. She’s talking about the fest’s May 9 opening-night film, “Thelma,” in which Squibb plays a 93-year-old grandmother determined to recover her money after she’s been scammed.

Writer/director Josh Margolin’s script, she said, was “beautifully written … So many film scripts, especially with young writer/directors, are overwritten. This one, never, not at all. It was just so perfect.”

It was, astonishingly, the first starring role in Squibb’s film career (though she’s played leads on the stage) — and it involved becoming a bit of an action star as well. Thelma, alongside her friend Ben (Richard Roundtree, in his final screen performance), chases after bad guys on a stolen scooter, climbs precariously onto a high bed, handles firearms and generally demonstrates a high level of badassery.

“They wanted to use a stunt double more than we did, and I said, ‘No, I want to try this,’” said Squibb, 94, who relished the physicality of the role. Most of the scooter driving, she said, is her, except for one wheelie: “I wouldn’t have known how to do that.”

Inspiration for the role came from Margolin’s real-life grandmother Thelma, now 104 years old, who was herself the victim of phone scammers (though, unlike the movie’s Thelma, the ruse was figured out before she could send them any money). Squibb studied videos of her before production and enjoyed meeting her after the film was done. (“Her mind is fantastic! She’s got a sense of humor that doesn’t stop.”) But her most treasured memory of the film was working with Roundtree, the legendary star of the “Shaft” franchise, who died last October.

“One of the joys of my life was working with him,” Squibb said. “He was so gentle and so sweet and loving. Everybody adored him.” She was able to meet Roundtree’s children when the film screened at Sundance in January. “I was thrilled because his oldest daughter had been living with him when he was shooting this, and she said he used to come home and say, ‘Oh, that June Squibb is kicking ass!’”

Born in 1929 in Illinois, Squibb spent many years as a stage actress, making her Broadway debut as the stripper Electra in the original cast of the musical “Gypsy” in 1960 with Ethel Merman as Mama Rose. (“She was wonderful; we all adored her.”) It was a challenging role, not least because it required having an electrician check her light-up stripper costume every time she went on stage.

She played the role for eight months on Broadway and then on tour; nearly 60 years later, Squibb made what she says is her last Broadway appearance, in the musical “Waitress” in 2018. It was “great fun,” she said, but rather tiring to do full weeks of performances in her late 80s.

Squibb was 60 before she began her transition into film. Based in New York at the time, she noticed that many fellow stage actors were getting film work, and asked her agent if he could find some film roles for her. In quick succession in the early 1990s, she was cast in Woody Allen’s “Alice,” Martin Brest’s “Scent of a Woman” and Martin Scorsese’s “The Age of Innocence.”

“All at once, it just happened!” she said. “Everyone started saying, ‘My god, she’s a film actress!’” Dozens of roles in film and television followed, including her Oscar-nominated turn as a tart-tongued wife in Alexander Payne’s “Nebraska” in 2013.

Quite possibly the busiest nonagenarian in Hollywood (where she now lives), Squibb has numerous projects coming up. “Thelma” opens in theaters in June, as does the Pixar sequel “Inside Out 2,” with Squibb voicing the role of Nostalgia. She appears in a new remake of “Don’t Tell Mom the Babysitter’s Dead” (which begins streaming this month on BET), filmed an upcoming episode of “American Horror Story,” and recently finished shooting “Eleanor the Great,” the directorial debut of actor Scarlett Johansson.