A bastard hybrid of “Smallville,” “Twilight” and any number of other angsty teen-themed sci-fi TV shows and movies, this Michael Bay production, adapted from a book by Pittacus Lore, feels like a co-production of the CW and the SyFy Channel that’s inexplicably escaped to the big screen. Even the visual effects are subpar.

Alex Pettyfer, a handsome but wooden young actor, stars as a humanoid refugee from the planet Lorien, forced—along with eight others—to flee to earth when their home world is annihilated by a vicious race called the Mogadorians. Now a small band of the evil aliens, who for some reason look like a cross between punks and Goths (though their facial gills and shark-like teeth may be more threatening than their tattoos), have come to earth to track the nine down and exterminate them—for some reason sequentially, since they all have numbers. Each of the refugees is accompanied by a protector, in our hero’s case a fellow named Henry (Timothy Olyphant).

As the movie opens, Pettyfer, who’s number four in the series of nine, is posing as a typical beach-loving Florida teen, but his unusual nature is revealed when a symbol on his leg blazes with light to mark the killing of another young fellow—number three—hidden away deep in the jungle (in a scene that’s eerily similar to one toward the start of “Jumper,” another movie from which this one cribs). Soon he and Henry have abandoned Florida and moved on to the little town of Paradise, Ohio, where he registers in high school under the imaginative name of John Smith.

Why Paradise? Because Henry is trying to track down an erstwhile amateur UFO chaser who apparently discovered a part of a Lorien tracking device before disappearing himself. Coincidentally John falls in at school with the man’s son Sam (Callan McAuliffe), a nerdy kid grieving his father’s absence who’s regularly mistreated not only by his nasty stepfather, but by campus quarterback/bully Mark (Jake Abel). He also links up with Sarah (Dianna Agron), the school shutterbug who just happens to be the ex-girlfriend of the still-possessive Mark. That puts our hero in the bully’s sights along with Sam.

But it just so happens that at this very moment John’s special powers—extraordinary agility and super-strength, expressed not only in the ability to pummel opponents but also to shoot glowing force-bursts from his hands—are emerging. That’s fortunate, because the Mogadorians are hot on his trail. It’s also fortunate that by the time they arrive, though Henry has bitten the dust John has gained the help of both Sam and Sarah, and expatriate Number 6 (Teresa Palmer), a real butt-kicker as well as a hottie, has ridden into town on her motorcycle to join forces with John and clobber their pursuers. Another pal John has acquired—a cute beagle—proves to be quite a help when the Mogadorians unleash their gruesome pet, a hungry beast that looks rather like a modified version of the Kraken from “Clash of the Titans” and threatens to gobble up everything in its path. The upshot is a major nighttime battle in which virtually the entire high school, including the football stadium, is reduced to rubble—something the remaining students will probably applaud.

It may be that in its original form, extending over hundreds of pages, “I Am Number Four” doesn’t seem so absurd. But with all the incident crunched into a hundred minutes, it comes across like all ten seasons of “Smallville” accordioned into a single feature. At the same time, however, it’s curiously sluggish, largely as a result of the plodding direction by D.J. Caruso, who draws dull performances from everybody in the cast apart from Olyphant, who injects some of his quirky persona into Henry, and Palmer, who’s like a teen Angelina Jolie—and the heavily-made up Kevin Durand, who camps it up mercilessly as the Mogadorian commander. But Pettyfer, Agron and McAuliffe are a glum trio, and their gloomy underplaying makes the movie feel simultaneously rushed and lugubrious.

For a Bay product the effects are second-rate too, with the light bursts ineffectual as a source of thrills and the big climactic sequence a murky mess. Otherwise Guillermo Navvaro’s lensing looks ragged and overly gritty, perhaps in an effort to emulate the first “Twilight” installment.

“I Am Number Four” ends with a setup for sequels—there are four more numbers out there somewhere, after all. But as with so many hopeful franchises, this one will probably be a one-time wonder.