For over a decade, the "Transformers" franchise has made its money on being big, dumb and loud, but with the third and fourth installments, 2011's "Transformers: Dark of the Moon" and 2014's "Transformers: Age of Extinction," director Michael Bay (2013's "Pain & Gain") had seemingly begun to correct many of the errors he'd previously made on 2007's "Transformers" and 2009's "Transformers: Revenge of the Fallen." Make no mistake, the writing remained a mess, but the unbearably cornball one-liners were less unctuous and the incoherent action of the earlier pictures—a chaotic, shot-too-closely jumble of screeching metal—had been traded in for more cohesive, diverting set-pieces. The latter two movies still weren't what could be considered good, but as grandiose popcorn flicks they succeeded in pummeling viewers into exhausted submission. With fifth entry "Transformers: The Last Knight," Bay has radically reversed course. It's as if he approached the film from the start as a twisted experiment to nonsensically emulate the series' most widely derided sequel, "Transformers: Revenge of the Fallen," as a means of testing his dedicated audience's will to stick by him even while serving up an insulting $260-million pâté of cinematic excrement.

The plot is beside the point, yet screenwriters Art Marcum & Matt Holloway (2008's "Iron Man") & Ken Nolan (2001's "Black Hawk Down") feel the need to provide lumbering exposition at every turn—so much exposition, in fact, one begins to question if reality has been replaced by a seemingly never-ending nightmare of déjà vu. By extension, good-guy Autobot alien Optimus Prime (voiced by Peter Cullen) says, "I am Optimus Prime," with such frequency and during so many unnecessary, inopportune moments it could very well make for a fatal drinking game.

All that really needs to be known is this (and this is still more than it deserves): harmony between humans and transformers is at an all-time low, not helped by the previous mass destruction of Chicago that has left the city abandoned and quarantined. An ancient 1,600-year-old staff once owned by magician Merlin (Stanley Tucci) holds the key to either saving or destroying the world, and everyone—the evil Decepticons; global paramilitary unit TRF; a desperate Optimus Prime hoping to save his dying home planet Cybertron; Sir Edmund Burton (Anthony Hopkins), the last member of the transformers-protecting Witwiccan Order—is in a race to find it. Also getting mixed up in the impending battle are Cade Yeager (Mark Wahlberg), now a junkyard-owner warrior for good with a crucial talisman from the Dark Ages in his possession, and polo-playing Oxford professor Vivian Wembley (Laura Haddock), the final descendant of Merlin whose family possessions hold the key to the staff's whereabouts. Meanwhile, Cybertron edges ever closer, on an apocalyptic collision course with Earth.

"I welcome the end of days!" an exasperated Vivian says during a key moment in "Transformers: The Last Knight." Long before its interminable two and a half hours of patience-testing nothingness are up, many viewers will be in total agreement with Vivian's sentiment. Here is a film of brazen, braincell-sucking inanity, bereft of even a scintilla of imagination and patently offensive in its contempt for audiences. Images move in front of one's eyes, but there isn't anything there to care about, to excite, to challenge, or to entertain. The only emotion the film inspires is disdain. Michael Bay could have recorded himself methodically setting fire to a state-of-the-art digital camera and it would have the same ultimate outcome as what has made its way to screens.

Where to begin with the untold monstrosities within? The human characters are bigger pawns than usual, if that is possible, on hand to do very little and say even less of consequence. Returning protagonist Cade Yeager, played by Mark Wahlberg (2016's "Deepwater Horizon") with a questionable haircut, has been stripped of his talent for invention and the one person in his life worth fighting for—teenage daughter Tessa (Nicola Peltz, briefly heard and never seen), away at college. Taking her place is plucky 14-year-old orphan Izabella (Isabela Moner), introduced and then abruptly sidelined for most of the running time until she reappears in the third act for no plausible reason. Anthony Hopkins (2014's "Noah"), bless his heart, looks like he'd rather be anywhere else, and who could blame him? Jerrod Carmichael's (2016's "Neighbors 2: Sorority Rising") painful wisecracking junkyard assistant Jimmy makes one long for the comparatively elegant comic relief of T.J. Miller in "Transformers: Age of Extinction."

Josh Duhamel (2013's "Safe Haven") returns to the fold as Colonel William Lennox, left to wonder why he bothered as he proceeds to stand around and do a whole lot of nothing. The same goes for John Turturro (2014's "Exodus: Gods and Kings"), as the Cuba-based Simmons, spending his minimal screen time talking on a payphone situated in front of giant Che Guevara wall art while ad-libbing embarrassing lines ready-made for the cutting room floor. If anyone escapes mostly unscathed, it is Laura Haddock (2017's "Guardians of the Galaxy Vol. 2"), a typically bright presence whose Vivian nonetheless must deal with harpy family members who obsess about her lack of a love life and a would-be love interest, Cade, who says romantic things to her like, "You—British lady—shut up."

The transformer and robot characters aren't people, and Bay has never cared to develop them beyond the jingoistic soundbites they utter ("Without sacrifice there can be no victory" is stated twice in case we missed it the first time). More damning is how so many of them talk like they're performing the worst stand-up material ever written. Izabella's tiny droid friend BB-8—sorry, I mean Sqweeks (voiced by Reno Wilson)—talks in sitcom one-liners, its favorite phrase being "Ay, Chihuahua!" A shameless C-3PO clone, the jaunty, crass, yet protective Cogman (voiced by Jim Carter), exclaims, "Now you're both on my shit list!" A transformer with a French accent, Hot Rod (voiced by Omar Sy), shows up for no reason other than for the movie to make a joke about misunderstanding his accent. The metal-cigar-chomping Hound (voiced by John Goodman) says things like, "My invitation to this ass-kicking must have gotten lost in the mail," without a hint of irony. Not to be outdone, another transformer dares to say, "Wow, would you look at the junk in her trunk," referring to literal junk in a trunk. The worst offense, however, comes from a Decepticon called Nitro Zeus (voiced by John DiMaggio), introduced with perhaps the most cringe-inducing one-liner that has ever been spoken aloud in any movie, ever: "Free at last, thank Megatron almighty, I'm free at last!"

If the action in the first two "Transformers" movies was done in by the incompetence of its lensing and editing, and the scenes of explosions, car chases, narrow escapes and citywide destruction in the following two features somewhat improved by offering at least a few genuine daring thrills, then the likeminded action in "Transformers: The Last Knight" is so ceaselessly uncreative and ineffectual it's as if they do not exist at all. A collection of quick shots strung aimlessly together does not a tightly constructed or memorable sequence make, and it helps matters none that Bay seems to have entirely checked out. As astronomically expensive and enormous in scope as this film is, there is no excuse for a filmmaker to stop trying and to clearly not even care, but all evidence in the finished product suggests these very things to be true.

"Transformers: The Last Knight" is irredeemable garbage that gives summertime blockbuster fare a bad name, an insufferable slog through terrible decisions, dreadful execution, and the flagrant pilfering of more money than most people will ever see in a lifetime. A blindfolded person with a gun pointed at his or her head couldn't pen a worse screenplay. A director who has just woken from a thirty-year coma and been immediately wheeled to set couldn't make a more inept feature. In an instant, Michael Bay has destroyed whatever minor progress he had begun to make, the lessons he learned about how to helm action and create a modicum of tension incinerated in the flames of his latest pyrotechnic stunt. Is there anything positive to be said? Yes. The CG-enhanced sky looks really pretty in one shot as a spacecraft rises out of the ocean. "Transformers: The Last Knight" is an endurance-testing assault on the art of cinema, one physical altercation away from becoming criminal.