Clive Owen, as sharpshooter Mr. Smith, helps a woman deliver her baby with one hand (to the tune of Nirvana's Breed) while fending off a bevy of bad guys with the other; later, he rolls around naked with Monica Bellucci (as the film's obligatory hooker with a heart of gold) while firing bullets at an onslaught of attackers, followed by a pun that you can probably figure out for yourselves.

Any junior high school kid with video-game expertise and a dirty mind could have written this stuff (Michael Davis, a grown-up, did, and he also directed) so it's really not worth getting worked up over. It's a parody of a genre that wasn't all that deserving of parody: the mindless, John Woo-style cornucopia of carnage.

Looking for plot amid the gunfire is also pointless; it has something to do with saving the aforementioned infant from a hit man named Hertz (a growling Paul Giamatti) and his henchmen, who are after the baby for his bone marrow.

But longtime Woo cinematographer Peter Pau, who won an Academy Award for Ang Lee's Crouching Tiger, Hidden Dragon, is responsible for the camerawork, so at least Shoot 'Em Up is a gritty visual feast. And much of the choreography can be inventive, with Smith sliding under tables, across conveyor belts and into moving vehicles to get his shot.

A mysterious, mild-mannered man whose pet peeves include drivers who refuse to use their turn signals when changing lanes, Smith is a stickler about eating his carrots (they're good for the eyes) but he's also happy to use his favorite vegetable as a weapon in a pinch. (This maneuver serves as one of the film's many sources of dark humor.) An intricate shootout in a gun factory, which Smith orchestrates by pulling a series of strings attached to the triggers of countless automatic weapons, is unexpected fun.

After about an hour, though, it all becomes a mind-numbing barrage.

Maybe that's the point but that doesn't make it entertaining. And the in-joke references to other movies, including the works of Sergio Leone and even Giamatti's own Sideways, are only vaguely cute.

Owen is coolly charismatic, as always, and looks like he's having a blast in the rare role that allows him to show some comic flair. Bellucci doesn't get to do much besides look buxom in her bustier. (Her character and Smith have some sordid history together, naturally, and so she agrees to help him tote the baby around through every elaborate showdown.) And Giamatti, who's repeatedly proven himself capable of bringing nuance to villainous characters who might otherwise have seemed two-dimensional, chews up the scenery real good but his shtick gets old real fast.

"You know why a gun is better than a wife?" he asks a couple of his minions. "You can put a silencer on a gun."

No one ever bothers to use the silencer in "Shoot 'Em Up." That would be an example of subtlety.

Shoot 'Em Up, a New Line Cinema release, is rated R for pervasive strong bloody violence, sexuality and some language. Running time: 93 minutes. Two stars out of four.