Emotions on display in ‘Transformers’ prequel

For about a decade now, the “Transformers” movies have existed so completely in their own bombastic universe — one packed with big fireballs, vacuous characters and orgies of mass demolition — that it has seemed sensible to speak less of quality than of bearability.

Few directors, after all, have pushed the boundaries of what’s bearable the way Michael Bay has.

Mercifully, Bay keeps his wrecking-ball aesthetics to a minimum in “Bumblebee” — which, compared with its larger, noisier brethren, proves to be a mercifully short, smooth ride.

“Bumblebee,” a prequel to the “Transformers” saga, was written by Christina Hodson and directed by Travis Knight. The difference is immediate: You can actually see and follow what’s going on when the giant Hasbro robots go at it — which they do in a smoothly executed opening sequence on the distant planet of Cybertron.

As pleasing as the sonorous tones of Optimus Prime (voiced again by Peter Cullen) are, the real hero of the story is Bumblebee, the scrappy Transformer with the striking yellow-andblack paint job and a heart of sweetest honeycomb.

Before he acquires his Earthling moniker, however, he is B-127, one of several rebel Autobots waging an intergalactic war on the dastardly Decepticons.

Severe losses conspire to send B-127 to planet Earth circa 1987, where he has the misfortune of crash-landing near a U.S. military training base and losing his voice (supplied briefly by Dylan O’brien) in a violent clash with a Decepticon tracker. He quickly learns to disguise himself as a battered yellow Volkswagen Beetle in a

junkyard. There, he is found and driven home by Charlie (Hailee Steinfeld), a teenage car buff who has no idea that her new ride is a shapeshifting robot — although she finds out soon enough.

Bumblebee can’t explain to her what he is, but his soulful blue eyes and shy, sensitive demeanor tell her all that she needs to know.

At this point, the film — a la “E.T.” and “The Iron Giant” — becomes a sweetly amusing tale of intergalactic friendship.

Steinfeld (“The Edge of Seventeen”) makes Charlie more than a regulation misfit heroine. When we meet her, she is indifferent toward her mom (Pamela Adlon), her stepdad (Lenny Jacobson) and her younger brother (Jason Drucker). At her high school, she is ruthlessly picked on by the hot guys and mean girls.

The family garage has long been Charlie’s refuge, the space where she spent hours working with her father before his untimely death. Now the garage is B-127’s refuge, and “Bumblebee” gets lovely, low-key comic mileage out of his scenes with Charlie. Their delicate rapport underscores how little the five previous “Transformers” films invested in the human element.

Which is not to oversell this similarly Cg-laden caper or to misrepresent the boilerplate machinations of the plot.

Bumblebee’s presence on Earth hasn’t gone unnoticed, and, soon, two vicious Decepticons — Shatter (Angela Bassett) and her trigger-happy henchman, Dropkick (Justin Theroux) — show up, wielding big guns and stock declarations of villainous intent. The military is forced to get involved; trucks explode, cars flip and human bodies liquefy.

Along the way, Charlie and Bumblebee learn important lessons, prove their heroism and save the world, even as their efforts point to more apocalyptic adventures on the horizon.

The ending packs a lovely surprise — not because you don’t see it coming, but because, for once, you’re not simply grateful that it has arrived.