Did you ever imagine that just by reading a film review you could become guilty of jaywalking? It’s true: For every word of this review you read, I will take one more step into the middle of the street, and into oncoming traffic. By the end of this paragraph, I’ll reach the yellow line, and it will be your fault.

It’s this dubious logic with which the new thriller “Untraceable” attempts to implicate all Internet surfers — and the movie’s own viewers — in a series of gruesome murders.

Jennifer Marsh (Diane Lane) is an FBI agent specializing in cyber-crime, and her team is working to find a sadistic, newfangled kind of killer. The mystery man has set up a Web site, grabbed a victim, and rigged an elaborate torture device. The more people who log onto his site, the faster the device works in killing its victim. News coverage and online buzz (and human nature that has remained unchanged for millennia) mean that each successive victim succumbs more quickly. Somewhere along the line — surprise, surprise — it turns personal for Jennifer.

It’s all pretty routine, and truly gruesome: One poor guy is submerged in battery acid, another slowly burned with heat lamps. The audience is forced to watch every boil and bubble of skin, and then implicitly chastised for its interest. But director Gregory Hoblit has a skill for building suspense, and the film is so tightly paced that viewers may end up on the edge of their seats in spite of themselves. What’s more, many of the quiet moments between Jennifer and cop Eric Box (Billy Burke) are nicely restrained. The script avoids the lapses into tedious explication that bog down so many similar procedural thrillers.

Mr. Hoblit (“Fracture”) and three screenwriters steadily build the case that there is danger lurking in all technology: A children’s video game infiltrates a top-secret computer file. An agent’s (Colin Hanks) interest in Internet dating lures him into violent trouble. Even the blips and beeps of security pass codes and in-car navigation systems become ominous here.

Jennifer, spouting the film’s Luddite thesis, chalks this up to the voyeurism nurtured by the Internet. Online, she says, we “check the news, see strangers have sex, and see a journalist get his head cut off.” It’s all just one click away, she implies, from murder.

That’s where the logic of “Untraceable” falls apart. Sure, the deaths are broadcast on a Web site, and its operator, with astonishing technological prowess, claims to be responding to his fans. But the real killing is done not by the soul-deadened Web surfers who log on to check out the newest and grossest thing, but by a classic pre-technological villain: a good old-fashioned psychopath in a basement. In the end, the Internet is just a tool. Evil requires a prime mover.

Ms. Graham is an editor for Domino magazine.