“Terminator: Dark Fate” rates as a fairly entertaining sequel to James Cameron’s low-budget, high-yield “The Terminator” (1984) and the hugely expensive and enjoyable “Terminator 2: Judgment Day” (1991). It has zero narrative connection to any of the interim lame-o “Terminator” movies that came for our money after those two, the most recent being “Terminator: Genisys” in 2015. Storywise we’re coming straight from “Judgment Day,” where the machine-learning apocalypse was averted thanks to Sarah Connor, played by Linda Hamilton. She returns here, looking fierce, hoisting enormous weapons of Terminator destruction and growling insults in a vaguely inhuman, seen-it-all-including-the-apocalypse way, with a chaser of Elaine Stritch.

The one true amazement in “Dark Fate”? That’s easy: the magical transference of biceps from Hamilton to Mackenzie Davis’ tank-topped, genetically enhanced soldier of the future. In a heavily digitized enterprise, they’re the most conspicuous human camera subject.

Screenwriters David S. Goyer, Justin Rhodes and Billy Ray set the main line of action in 2020, mostly in Mexico and Texas. Davis’ unblinking humanoid, named Grace, zwoops in from the year 2042 in order to protect a Mexico City factory worker, Dani Ramos (Natalia Reyes), from the ruthless Rev-9 android (Gabriel Luna) programmed to kill her. He keeps his hair neat and trim so that nothing slows him down.

Dani is Sarah’s heiress apparent in the apocalypse prevention department; that department is the franchise’s reason for being; and “Dark Fate” eventually manages the return of Arnold Schwarzenegger as the now-domesticated Terminator, now living outside Laredo, Texas, with a wife and a stepson. He goes by “Carl” and has a drapery business. (This is played for some pretty good laughs.) Carl’s relationship with his woman is strictly nonphysical; as he monotones in one lyric interlude, explaining his own machine-learning curve, “She appreciated I could change diapers efficiently and without complaint.”

Now we’re getting somewhere, I thought during this scene, and you could feel the preview audience relaxing into it. The rest of the movie settles for medium-grade action proficiency. It’s so heavily digitized, it’s essentially a digitally animated feature with occasional flashes of a human heartbeat. In the first big blowout, Rev-9 — who can divide himself in two, leaving an exoskeleton to drive a speeding truck while his human-looking half does the heavy lifting — sets his sights on Dani and her brother in the factory. Director Tim Miller and editor Julian Clarke worked together on “Deadpool,” and at their sharpest they have a canny way of cutting into and away from the full-on migraine brutality of the moment. As “Dark Fate” proceeds, the action becomes increasingly ridiculous and outlandish and routine.

No action franchise item is made for everyone; considering the misogynist online trolling that greeted one poster image, the one featuring the three female leads (and this is a female-led picture, all right), “Dark Fate” may end up being a divider, not a uniter. Its empathetic depiction of Mexicans may send the “Rambo: Last Blood” crowd into a funk and a dither (bad combo), and there’s an extended sequence (the best-paced scene in the movie) set in a U.S. Border Patrol detention center, complete with, yes, undocumented migrants in cages. We can all look forward to “LIBERAL PROPAGANDA?” headlines on Fox News, although the movie’s hardly that. Anyway, having one foot in the real world always helps ground science fiction.

The franchise feels close to fished out at this point. “Dark Fate” works best when it’s basically a road picture featuring three women trying to make their scenes as human, and compelling, as possible under the filmmaking circumstances.