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Here's a great idea: a humanoid alien, with amazing powers, living on Earth amongst us, who answers to the name of John Smith. Hang on, isn't that Doctor Who? And specifially the David Tennant episode where he's on the run from monsters? Or how about a film where the surviving babies from a doomed planet are sent to Earth with amazing powers which they are advised to keep hidden from the indigenous population? No, that would be Superman. And specifically Superman 2, when the same monsters turn up and fight the hero in an ordinary American town.
Still, once you get over spotting the similarities, I Am Number Four is a reasonably entertaining popcorn diversion: a slick if soulless SF action thriller for teens in which Alex Pettyfer is "John Smith", an alien brought up as a hunky surfer-dude human after his planet was overrun by the evil, world-destroying Mogadorians (bald, tattooed, pointy-toothed, with gill-like flaps in their faces). There were just nine of Smith's race left; three of them have already been killed by a Mogadorian hunting squad on Earth, and they're now after him. Even after relocating to Ohio, they're on his tail, especially when he unwisely starts uses his superpowers to protect the cute blonde girl and the resident science geek from the thuggish bullies in the football team....
It's very silly, and it's not massively well written (there is some pretty ropey dialogue and character stuff), but efficiently done and rattles along harmlessly: there's a lot of CGI and spectacular monster action in the latter half as the various aliens slug it out at the local high school. Sadly, it doesn't have a decent ending, having Smith set off to find his fellows with a completely different (and substantially hotter) chick, and leaving his genuine love interest in the care of the violently possessive sports jock. Maybe they're trying to set up I Am Number Five. On a cold Tuesday afternon, it's a tolerable if unremarkable couple of hours. Produced by Michael Bay.