Science fiction purists, take heart: ‘‘I, Robot,’’ starring action god Will Smith as a futuristic Chicago cop investigating an alleged robot-on- human murder, isn't the dumbed-down affront to the memory of novelist Isaac Asimov that some alarmist elements have feared. And by ‘‘alarmist elements,’’ I mean, of course, geeks.

Yes, the movie does star Smith, whose ‘‘Men in Black’’/‘‘Wild Wild West’’ pedigree seems ill-suited for Asimov's moody, parable-driven source material. And, yes, sometimes it does feel like we're watching a robotic version of ‘‘Arachnophobia,’’ with thousands of androids swarming the Windy City like metal locusts. But it could have been so much worse. Smith could have written a song for the soundtrack: ‘‘Gettin' Jiggy With I.T.’’ or something equally disillusioning.

As it turns out, director Alex Proyas (‘‘Dark City’’) strikes a nice balance of geekitude and populism in ‘‘I, Robot,’’ a gorgeously rendered, pavement- pounding thriller that respects its audience enough to seriously mull the provocative question of man's relationship with his machines. Though it exhibits all the symptoms of a brainless action movie — macho posturing, pithy one-liners, improbable stunts — it somehow manages to avoid being brainless itself.

The year is 2035, and America has gone to the droids. Robot butlers, robot nannies, robot short-order cooks — everywhere you look, robots are obediently and non-violently serving mankind. Manufactured by a monopolistic concern called U.S. Robots, the machines are governed by the Three Laws of Robotics, a cybernetic Constitution of sorts that forbids robots from harming human beings and places their own well-being below that of their flesh-and-blood masters.

The Three Laws are Asimov's chief legacy in the movie — little else bears any resemblance to author's original 1950 book, an anthology of interconnected robot-themed short stories that played an influential role in the evolution of such modern robot characters as Data from ‘‘Star Trek’’ and Bishop from the ‘‘Alien’’ movies.

Three Laws or no, homicide detective Del Spooner (Smith, sassy as ever) immediately suspects robotic foul play when a top cybernetics researcher, Dr. Alfred Lanning (James Cromwell from ‘‘L.A. Confidential’’), falls to his death from his office at U.S. Robots. No one buys his theory, and for good reason — Spooner is so technophobic and robot- hating that he still uses an analog alarm clock and refers to the droids with an unkind epithet toward the droids.

"Maybe you would have banned the Internet to keep the libraries open," sneers Lawrence Robertson, the CEO of the company, which could lose billions if the public loses faith in the safety of his product.
With the help of a skeptical ‘‘robo- psychologist’’ named Susan Calvin (Bridget Moynahan), Spooner does unearth a suspect: Sonny, a prototype robot with an eerily translucent, human-looking face, who passionately maintains his innocence. Played by Alan Tudyk — the pirate guy in ‘‘Dodgeball: A True Underdog Story’’ — Sonny is the most compelling character in ‘‘I, Robot,’’ a wide-eyed naif whose capacity for human emotion (and ability to flout the Three Laws) could hold the key to Spooner's investigation, or spell the end of human civilization as we know it.

As Spooner gets closer to exposing a conspiracy at the heart of U.S. Robots, he becomes a hunted man himself, setting the table for a series of gut- ripping action scenes, including one in which a homicidal platoon of robots leaps off a magnetically powered semi and attacks Spooner's Audi as it speeds down a Chicago expressway.

The script, by screenwriters Jeff Vintar and Akiva Goldsman (who won an Oscar for ‘‘A Beautiful Mind’’), doesn't always hold up to scrutiny — in this world of phone-cameras and advanced forensics, you'd think Spooner would have no trouble proving to his superiors that he was attacked by four dozen killer robots — but it finishes nicely, with a surprise culprit and a mind-blowing denouement.
In the annals of movie robotics, I'll take "I, Robot" over that dipwad in ‘‘Short Circuit’’ any day.

‘I, Robot’
Grade: B
Starring: Will Smith, Bridget Moynahan, James Cromwell, Bruce Greenwood
Rating: PG-13 (intense stylized action, some brief partial nudity)
Running time: 117 min.
Playing: Opens Friday at theaters Valleywide