Michael Bay is the kind of filmmaker who has always understood machines better than people. In his films, chrome hurtles through space with a sensual weightiness; the clangs and thuds of metal against metal send a frisson down the spine. “Transformers: The Last Knight” does not stray from this formula, except that it is more; it is the most. It’s shinier, louder, crazier; it’s a fidget spinner jacked up on steroids.

But while Bay whips up an impressively frenzied, machinated opera, the humans are another story — they’re not even an afterthought. That has never been more apparent than in this installment of the film franchise about alien robots inspired by a cartoon from the ’80s.

The plot is a series of increasingly baffling events, proceeding from the Dark Ages of England, to outer space, to modern day Cuba, to Chicago, to South Dakota, then back to England in the space of the first 25 minutes. That relentless pace never, ever lets up for the 2 hour, 26 minute running time. Watching it feels like hanging on to a bucking bronco for dear life.

It’s hard to imagine anyone reading, let alone writing, the script and believing that it made any sort of sense at all. Aside from the absolutely insane plot — it would be a fool’s errand to attempt to describe it — there isn’t any character development. Only Optimus Prime is given a proper arc, and he disappears for the middle hour of the movie. Standing in for wit and humor is a pastiche of meaningless pop culture references, tooted by Bumblebee’s scanning radio voice, or chirped in a proper British accent by new transformer butler Cogman.

Unfortunately, the many credited writers also decided to attempt a poorly executed gesture at girl power through the characters of Vivian (Laura Haddock) and Izabella (Isabela Moner). Vivian is an accomplished professor who is badgered by her mother and colleagues about her love life, and costumed as if she’s in the video for Van Halen’s “Hot For Teacher.” Izabella is a scrappy orphan mechanic who fulfills the daughter role for Cade (Mark Wahlberg). Though she’s only 14 and declared a “little girl,” Bay’s camera can’t help but leer at her too.

“Transformers” could have been a camp masterpiece if not for the misguided humor, misplaced self-seriousness, and jokes that become increasingly, uncomfortably sexist. Only Tony Hale and John Turturro seem to know what a silly movie they are in, and they commit fully, especially Hale as an epically stressed out NASA scientist. Star Mark Wahlberg seems to be in a “Saturday Night Live” sketch about himself — you half expect him to tell a Decepticon to “say hello to ya motha for me.”

This is Bay’s world, and when faced with the end of the world, there’s only one message to be gleaned from this entry in the “Transformers” franchise: The Mack trucks and the muscle cars will outlive us all.

MOVIE REVIEW

“Transformers: The Last Knight”

Grade: D+

Starring Mark Wahlberg, Laura Haddock and Anthony Hopkins. Directed by Michael Bay.

Rated PG-13 for violence and intense sequences of sci-fi action, language, and some innuendo. Check listings for theaters. 2 hours, 26 minutes.

Bottom line: A melee of crashing metal in an insane plot