This is a pretty cool movie and all, but at some point you just have to pause and say, "Huh?" To borrow a phrase from the great and wise Ricky Ricardo, this movie has some 'splainin' to do.

Heaven knows I love watching a young woman kick butt every which way from Sunday, and there's nothing sexier than the bare-midriff look Milla Jovovich has going throughout this film, but -- and maybe I'm old-fashioned -- I sort of expect a movie to explain at least a few of its most unusual facets.

For example, our heroine in this film can pull weapons out of thin air, make her hair and clothes change colors on a whim and has no respect for gravity. All I know about her is she was a normal human being who caught an engineered virus that turned her into a hemophage, died, was restored to life for further testing and escaped. I can buy into the whole heightened senses thing, but how this allows her to morph and avoid hails of bullets fired directly at her is quite beyond me. While I'm at it, let me also say that the central storyline has more cracks in it than, uh, something full of cracks. The ending is pure deus ex machina, squared.

The movie starts off great, though. I really liked the comic-book montage style of the opening credits, and the film itself wastes no time in throwing Violet (Jovovich) up against hordes of bad guys trying to kill her. The point of her initial raid is to steal a new weapon the humans have designed, a weapon supposedly capable of wiping out Violet and all her fellow hemophages. Said weapon turns out to be unlike anything you would expect, and Violet's decision to protect it rather than destroy it sets the stage for the remainder of the film. Her hemophage allies want the weapon either brought to them or destroyed, Vice Cardinal Ferdinand Daxus (Nick Chinlund), the weapon's creator and all-around power-hungry tyrant, wants it back, and Violet has to forge her own path through all this mess.

Obviously, the filmmakers just wanted to show 90 minutes of Jovovich doing what she does best, and the plot they threw together is really just a means to that end. The basic storyline is easy enough to follow, but far too many of its details go unexplained. As for the special effects and fight scenes, there's some really gnarly stuff on display here, but a lot of the CGI work is just overkill. Additionally, the cameramen are like kids with a new toy as they experiment with every angle known to man.

Despite its inherent weaknesses, though, I really enjoyed the first hour or so of this film -- and then the novelty of all the fast and furious action wore off, leaving me to wade through another half hour of a pretty slippery and generally unimpressive story. Even the action goes downhill as the climax approaches, as too many of Violet's fights prove to be laughably easy -- and accompanied by incredibly cliched dialogue. The bottom line is this: Ultraviolet will definitely get your blood pumping, but it inevitably puts your brain cells on standby.