Originally Published: 08 JUN 23 09:37 ET

Review by Brian Lowry, CNN

(CNN) — The seventh entry in the toy-turned-movie franchise that began in 2007 (including the most recent “Bumblebee”), “Transformers: Rise of the Beasts” reaches into the past in more ways than one, offering a simple-minded strain of giant-robot combat. Much in need of a script tune-up, it’s a less-than-meets-the-eye summer-movie machine, and not a particularly well-oiled one.

The main wrinkle – beyond the introduction of animal-shaped Transformers known as Maximals – involves setting the action in 1994, although other than the well-chosen musical soundtrack and a fleeting glimpse of the O.J. Simpson trial, the audience might be hard-pressed to notice it.

The plot, such as it is, involves the Autobots – under their leader Optimus Prime (again voiced by Peter Cullen) – teaming up with the Maximals in an effort to thwart the evil Terrorcons and a world-devouring threat known as Unicron, who, for those familiar with Marvel lore, basically comes across as a poor-bot’s version of Galactus.

The unfortunate humans given the thankless task of not only helping to save the world but having to spend most of their screen time gazing upward with awe are played by Anthony Ramos (of “In the Heights” and “Hamilton” renown) and Dominique Fishback (most recently seen in the Amazon series “Swarm”), both good actors deserving of better. They wind up joining with the skeptical Optimus in pursuit of a key that could potentially return the Autobots to their home, but in the wrong hands threatens to turn Unicron loose on an unsuspecting galaxy.

Basically, once you get past the celebrity voices added to the mix – a roster that includes Michelle Yeoh, Pete Davidson, Peter Dinklage and Ron Perlman – the whole exercise boils down to the scope and scale of the robot battles, which are impressive in their technical virtuosity if characteristically chaotic.

The movie bogs down, alas, during almost every stretch in between – especially when the humans take center stage. And like several of this summer’s sequels, “Rise of the Beasts” doesn’t seem content to tell a single story without planting seeds for more, which doesn’t conjure much enthusiasm after a product with this much of an assembly-line feel to it.

Granted, given its roots in the Hasbro toys (and the animated TV show spawned in the 1980s), “Transformers” has always served more as a showcase for what 21st-century visual effects can achieve than anything else, and almost has to be graded on that curve.

Yet even by those standards, “Rise of the Beasts” lacks the disarming wit that somewhat elevated “Bumblebee,” and the attempt to turn Davidson’s character, Mirage, into plucky comic relief mostly comes up flat.

After directing the first five movies, producer Michael Bay has handed the toolkit over to Steven Caple Jr. (“Creed II”), without any discernible change in tone or style. “Transformers’” main advantage could simply be that it’s been six years since “The Last Knight,” which might create a bit of pent-up demand for the property among those who celebrate.

Beyond such loyalists, though, everything here, pardon the expression, looks more than a little past its Prime.

“Transformers: Rise of the Beasts” premieres June 9 in US theaters. It’s rated PG-13.