(CNN)Even grading on a curve, "Transformers: The Last Knight" is a bloated, tedious sequel, one that spends gobs of time explaining a disjointed plot whose parameters barely come into focus. Again clocking in at roughly 2 ½ hours, it's a pretty good reason not to squander another night on this toy-inspired franchise.
Director Michael Bay still possesses a knack for big, kinetic action sequences, but it's everything else about this fifth edition -- which trots out familiar faces while adding a few new ones -- that feels like an endurance test. Anthony Hopkins can't even class up the joint.
Then again, "Transformers" isn't so much a movie at this point as a global merchandise-delivery system. Given that, it seems misguided to expend so much energy on lame banter and attempts at wisecracking humor -- even in the midst of fight scenes -- when all that's really required is a perfunctory set-up to watching giant mechanized warriors bash each other.
Instead, the movie opens in the Dark Ages, with a massive battle involving King Arthur and his knights. Merlin, it turns out, owed his "magic" to a relationship with an early Autobot visitor, sowing the seeds for a world-imperiling threat that will arise 1,600 years later.
Once again, the resourceful Cade (Mark Wahlberg) is at the center of it all, having come into contact with an object that could hold the key to Earth's salvation. Optimus Prime, meanwhile, the Autobots' towering leader, remains absent for a long stretch, leaving an assortment of his pals to help hold down the fort.
The idea of finding an ancient artifact to ward off an intergalactic enemy sounds workable enough. It's the elaborate mythology around it that proves numbing, along with the fact that virtually every attempt at eliciting laughs yields crickets at best and groans at worst.
In the service of the former, poor Hopkins has to deliver a flurry of exposition in the middle of the movie -- including an unnecessary detour to Nazi Germany, apparently in vain pursuit of justifying the epic length and scale.
The shortcomings likely won't keep "Transformers" from rolling off the assembly line, with the franchise's growing international appeal offsetting diminishing domestic returns. (The fourth film, notably, earned more than 75% of its box-office gross from markets outside North America.)
Hopkins isn't the only actor ill served by this mishmash, just the best. Indeed, the humans generally prove more two-dimensional than the Transformers, with Laura Haddock as a British scholar in a "stripper dress," as Cade puts it, ostensibly so he'll have someone to flirt with while they dodge large chunks of debris.
Most of the characters, in fact, basically serve to check off demographic boxes, such as the plucky orphaned teenager (Nickelodeon star Isabela Toner) who awkwardly stumbles into Cade's orbit.
"I'm useful," she explains near the outset. "I fix sh**."
Such skills are useful. After sitting through this "Last Knight," the real shame is that they didn't turn her loose on the script.
"Transformers: The Last Knight" premieres June 21 in the U.S. It's rated PG-13.
