Ben 10: Alien Swarm, Cartoon Network
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Caution: potential spoilers.
This is based on the animated series Ben 10: Alien Force. It's the second live-action movie based on the Ben 10 franchise. Of course, the actors playing Ben and Gwen are necessarily different from the previous movie, since it's set like 5 years after the original cartoon. But the actor playing Max is unnecessarily different (Barry Corbin here, as opposed to Lee Majors in the first movie). I can't really say if the movie is considered canonical either within the realm of the previous live-action movie, or either cartoon series. But as for the cartoon, it's clearly set prior to the third season of "Alien Force," considering Kevin appears mostly in human form, and has the same power he has in the first two seasons.
In any event, the movie starts with Kevin meeting someone who wants to sell some alien tech. The guy is just a middle man, and of the people behind the deal, only one is really important: a girl named Elena. Apparently, she was acquainted with Ben and Gwen a couple years prior, sometime in the interim between the two cartoon series. She's the daughter of a former Plumber, Victor Validus. He had been dishonorably discharged for stealing alien tech, or whatever. Ben and Gwen's grandpa Max had been particularly hurt by his betrayal, as we learn a bit later. Meanwhile, the tech that was being sold was just an excuse for her to meet up with Ben and ask for his help, but the meet went sour when some freak activated the tech, which was actually nanotechnology (at least they called it that), biological computer chips or whatever (which were too big in my book for the prefix "nano" to be attached). The chips attacked, but our heroes manage to force whoever was controlling the chips to withdraw.
Ben, Gwen, Kevin, and Elena return to Max's command center to study the chips or whatever, but when Max shows up, he orders Elena to leave and the others to have nothing to do with her. But Ben refuses, and leaves with her to help her, because she said her father had been kidnapped. Later, Gwen and Kevin investigate the matter on their own, and eventually are reunited with Ben and Elena. And there is some alien group called the Hive, which apparently Victor had warned Max about three years ago, though Max didn't believe him. And now they're using the chips to infect humans, take control of their minds, and plan to do the same with the entire human race.
Well, eventually Max gets taken over by one of the chips. And the kids figure out where the Hive's queen is, and go looking for her. Ben ends up using the Omnitrix to transform into a drone something like the chips (he calls the form "Nanomech"), and battles the queen (who was possessing Victor, to produce more chips). Predictably, our heroes win in the end, and everything returns to normal. And I don't really know what else to say. Except of course, the special effects were reasonably decent, including Ben's transformations, as well as Gwen and Kevin's powers. (Aliens Ben transformed into who are familiar from the cartoon included Big Chill and Humongousaur.) The writing wasn't the best, nor was the acting. I think the actors were probably trying too hard to be cartoons. But whatever, it was okay.