Somewhere in "Untraceable," amid the computer jargon (Trojans, Backdoors, mirrors and lots of other stuff I didn't understand but now fear) and the gruesome deaths, there's a nifty notion for a thriller.

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'Untraceable

2 stars = Mediocre
Ratings explained

• Starring: Diane Lane
• Rating: R for some prolonged sequences of strong gruesome violence, and language

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But in exploring the way the Internet feeds an insatiable, sick appetite for disturbing or sordid images -- car wrecks, suicides, torture porn -- "Untraceable" serves up those very images. I noticed a couple of people slip out of a preview after the movie showed what happens to human flesh in water laced with sulfuric acid.

"Untraceable" stars Diane Lane as Jennifer Marsh, an FBI agent in Portland, Ore., who specializes in cybercrime.

She lives with her mother and 8-year-old daughter and works nights, bantering with her partner, Griffin Dowd (Colin Hanks), as they troll for Internet predators or thieves who steal credit card numbers and other financial data.

Their workaday world changes when they get a tip about a Web site, streaming live, that shows the torture and death of a kitten and quickly graduates to humans. The site is rigged so that the more visitors it has, the faster the victim will die.

Jennifer cannot shut it down. It's revolting, sophisticated and untraceable as it transmits images of gruesome deaths, and it's getting more popular with each passing murder.

Her boss tries to warn the public: "Any American who visits the site is an accomplice to murder. We are the murder weapon." But that has no effect, with each kidnap victim dying at a faster rate as more and more users are drawn to the site.

As always, particularly if you saw the TV ad that gives away a couple of twists, it gets personal for Jennifer and her colleagues.

"Untraceable" bears some resemblance, and not in a good way, to 2007's "The Condemned." A TV producer dropped 10 former death-row prisoners on a remote island, told them to "kill or die," and charged people to watch the live feed.

It, too, delivered ugliness, brutality and violence, even as it condemned the people watching it.

"Untraceable," directed by Gregory Hoblit, whose credits include last year's "Fracture" with Anthony Hopkins and Ryan Gosling in their own cat-and-mouse game, lays out the dots of blood and then connects them.

But when it does, with a script by Robert Fyvolent, Mark Brinker and Allison Burnett, it can seem like diabolical just deserts or illogical, as the killer commits the very cybercrime that is so enraging.

It makes a point about the dispassionate nature of computer images (the same might be said of cable TV, which has turned coverage of celebrity deaths and distress into another form of pornography), but it does so with R-rated torture and murder.

Like Jodie Foster, Laura Linney and Julianne Moore, Lane is one of those actresses who can portray strength and intelligence without compromising femininity. We root for her to get her man, not in the "27 Dresses" way but in the tradition of lawman and criminal.

Except now, instead of pulling the trigger, it's about clicking the mouse.