"Untraceable" is a competently crafted serial-killer yarn that aspires to transcend its unapologetically lurid brethren: such franchises as the "Saw" and "Hostel" movies. It doesn't always succeed.

While it hectors against the morbid curiosity of Web surfers who ogle downloads of decapitations, car wrecks and self-immolations, it serves up its own brand of voyeuristic horror for the viewers' delectation. Still, its depictions of pain and suffering are fictional, while the Internet's are often too real. Though it's doubtful that this movie will deter someone from clicking on a scene of real mayhem, there is always hope that a switch will click on in the brain's realm of conscience.

Diane Lane, who brings heart and smarts to this formula thriller, plays FBI agent Jennifer Marsh. She works nights in the Portland, Ore., bureau's cybercrime division. There, she pursues sexual predators and Internet con artists with the click of a keyboard. One night, she catches a different kind of case. A kitten is being tortured and killed on a live Web feed with an advisory that promises bigger things are yet to come. This puts Marsh on the trail of the cyber-sicko who quickly raises the stakes.

The next victim is human, and he's tortured on screen in a way that lets cyber-viewers speed up the death process. The more viewers who log on to the site, the quicker the man dies. This is not a deterrent to those seeking sick thrills. Fans of the site alarmingly increase and eagerly await the next atrocity.

Of course, agent Marsh needs loved ones to be cast in harm's way. She's a widow who lives with her mother and her own daughter and she has a buddy played by Colin Hanks. There's also a handsome homicide detective played by Billy Burke who almost -- but doesn't quite -- bring romance into the equation.

As the law officers draw closer to the sociopath, it becomes evident that he's a mad genius. But the sadistic killer played by Joseph Cross doesn't fill the big shoes of such wackos as Anthony Hopkins' Hannibal the Cannibal and Robert De Niro's insane avenger in "Cape Fear." He's, dare we say it, a computer nerd who has an unconvincing ability to engineer elaborate and imaginative ways to kill people. Such movies need their monsters to be larger than life, and this one's a dweeb.

Director Gregory Hoblit manages to bring a sense of realism to this story by a committee of writers through the grainy imagery and understated performances. But it's Lane who grounds the movie in believability. As she demonstrated in "Unfaithful," she's an actor with an astonishing ability to convince audiences that they're seeing a real person with a complexity of emotions. Like all the best actors, she takes it to the wall, whether the result is great art or merely a commercial commodity.