Stephen Chow's "Kung Fu Hustle," which is set in a make-believe Shanghai of the '30s, tips its hat to the Hong Kong martial-arts movies of Bruce Lee and Jackie Chan while zooming into the 21st century via "Matrix"-style digital effects. What this broadly comic adventure most resembles, however, is a "Road Runner" cartoon brought to life. When the actors chase each other down a road, they go into hyperdrive, traveling at the speed of sound as their unicycle legs leave behind tunnels of cartoon dust. As deliberately artificial as an old studio musical (and it even includes a big dance number), "Kung Fu Hustle" defies all laws of gravity in its pursuit of thrills and laughs--and it's so disarmingly eager to please that only a stone-faced kung fu purist could object.

Chow, who wrote, directed and stars as a wanna-be gangster, is a huge comedy star in Asia, where "Kung Fu Hustle" is already a smash success. He's made more than 50 movies, though in the United States he's known for only one, the kung fu sports comedy "Shaolin Soccer." Co-financed by Columbia Pictures and armed with action choreographer Yuen Wo Ping (of "Matrix" and "Crouching Tiger, Hidden Dragon" fame) and an arsenal of computer-generated effects, "Kung Fu Hustle" is his bid for international success.

It's likely to pay off. The plot pits the ruthless members of the Axe Gang, who run the corrupt city, against the odd and seemingly overmatched denizens of Pig Sty Alley, a teeming apartment complex whose inhabitants, it turns out, possess unearthly fighting skills, such as a chain-smoking harridan of a landlady with a scream that can do more than shatter glass. The gang, alarmed by this unexpected resistance to its power, must hire ever-more-stupendous assassins to take on the quirky old locals, while our hero, Sing (Chow), morphs from a feckless would-be villain into a hero with supernatural powers. Amid the surreal and nearly nonstop mayhem, Chow finds little pockets of poignancy: watching these gallant old-timers bite the dust can produce an uncartoonlike pathos. Those moments don't last long, however: the raucous "Kung Fu Hustle" is painted in bold, cheerful strokes. Chow's martial-arts movie is exuberantly silly.