The opening line of Brett Easton Ellis’ “Less Than Zero,” about people being afraid to merge in California, might have served as the inspiration for Paul Haggis’ ensemble drama “Crash,” which treats racism in Los Angeles in the same interconnecting-stories fashion that “Traffic” applied to the drug trade. Though the technique of shifting from story to story unavoidably gives the whole a slightly schematic feel (especially in view of the coincidences the approach entails) and doesn’t allow for the individual characters to be developed as fully as they might, and though the cynicism can come across as flippant and the positive turns as manipulative, as a whole the tapestry still carries a powerful cumulative impact.

Just cataloguing the major characters that are shuffled together by dealers Haggis and Bobby Moresco is a daunting task. Two bickering African-American guys loitering in a ritzy section of town, Anthony (Chris “Ludacris” Bridges) and Peter (Larenz Tate), carjack an SUV from D.A. Rick Cabot (Brendan Fraser) and his wife Jean (Sandra Bullock). When a police call goes out, veteran cop Ryan (Matt Dillon) and his rookie partner Tom Hanson (Ryan Phillippe) pull over Cameron Thayer (Terrence Howard), a television director, and his wife Christine (Thandie Newton), and the racist Ryan proceeds to manhandle the woman suggestively while her husband is forced to look on, infuriating her and disgusting the idealistic Hanson; Ryan also shows his unenlightened attitude toward an HMO worker (Loretta Devine) whom he tries to prod into securing better treatment for his ill father. Meanwhile the Cabots call in a locksmith, Daniel (Michael Pena) to change the locks at their home, but he’s insulted by Jean’s snide remarks about his appearance; Daniel will also have a run-in with an Iranian shop owner, Farhad (Shaun Toub), who’s recently bought a gun to protect his property. Elsewhere Detective Graham Walters (Don Cheadle), who’s sleeping with Ria (Jennifer Esposito), becomes enmeshed in an investigation of a black policeman shot by a white undercover cop–a case that Cabot wants to prosecute ostentatiously in order to overwhelm the story of his being carjacked. (In L.A., Haggis and Moresco seem to say, Tip O’Neill’s old adage has suffered a slight change: here all politics are racial.) Walters is also asked by his aging mother (Beverly Todd) to find his younger brother, who hasn’t been home in days. And elsewhere, Anthony and Peter run into a Chinese man with their stolen SUV and find themselves unable to fence it because of the blood.

And all of that is only the beginning of the overlapping threads the screenwriters have in store. Anthony and Peter try a second theft, this time involving Cameron; a reassigned Hanson is the first officer on the scene, and he’ll meet up with another of the characters later as well. Christine will encounter the hated Ryan a second time too, but under very different circumstances. And Graham will not only find out something about the case he’s investigating that will cause him a moral dilemma, but also confront a family crisis. The central point in these later exchanges is encapsulated in the remark Ryan makes to Hanson when he finds that the younger man has requested a transfer to get away from him: “You think you know who you are. You have no idea.” As “Crash” moves from encounter to encounter, those who at first appear heroic may become villains and those you might initially detest may do something remarkable. Some characters learn to reconsider their prejudices and others find, to their horror, that they harbor them. Others are saved from disaster by the most unlikely twists of fate while others suffer undeserved catastrophes. There’s a semblance of poetic rhyme, but not much logical reason, to the linkages, separations, twists and turns that tumble over one another; some seem strained or obvious, but others are genuinely surprising, and a few bring touches of biting humor as well. The picture seems to say: this is just how things happen in an imperfect world–we’re all flawed, capable of good and evil, and capable of helping or hurting one another, and we never know what will draw us to the one or the other.

Haggis’ picture makes this point incisively in swift strokes, and it’s been assembled like an intricate puzzle whose parts fit together snugly and ultimately reveal a coherent message. It’s also populated by actors able to sketch their characters quickly and reveal their essential traits almost in short-hand. They’re all strong, and to mention Dillon, Bridges, Phillippe, Newton and Tate as standouts shouldn’t be taken as a reflection on the others’ contributions to an outstanding ensemble. Nor should one make too much of the fact that Cheadle looks uncomfortable smoking Walters’ cigarettes, a prop that he would have been better off without. “Crash” was obviously a labor of love not just for Haggis, Moresco, and Cheadle (who also produced), but for all the performers, who throw themselves into their parts with unusual intensity and conviction. The physical production is solid, too, with J. Michael Muro’s widescreen cinematography giving the locations a gritty sense of reality. Hughes Winborne’s editing, of course, is especially important in the success of a picture as narratively complex as this one.

It has to be admitted that “Crash” doesn’t match its kaleidoscopic surface with an equal degree of psychological complexity, and that its kinetic energy obscures the fact that it tends to repeat the points it makes. But it would be ungracious indeed to emphasizes its weaknesses in the face of all it has to offer. The film may be a trifle shallow in its treatment of its important topic, but it has an energy that carries you breathlessly along to a powerful conclusion.