Police buddy movies tend to get by on the routine glibness of their odd-couple dichotomies (he's white -- he's black! He's crazy -- he's by the book! He's coming off a hit -- he needs a hit!). So it was with a certain dutiful resignation that I sank into the opening minutes of Hollywood Homicide. This sprawling, big-dog action comedy features a couple of LAPD detectives who couldn't be more coyly mismatched. For a while, as the audience is asked to tick off the pair's precious contrasting character traits, you may feel as if you're seeing walking, talking versions of the index cards -- all half a dozen of them -- that went into the creation of the script.
Joe Gavilan (Harrison Ford), a weary veteran of the force, is a Motown fanatic whose cell phone rings with the opening riff of ''My Girl''; the phone of his junior partner, K.C. Calden (Josh Hartnett), plays ''Funkytown.'' When Joe saunters onto a murder scene, the first thing he does is to order up some chow -- a cheeseburger, well-done, with ketchup and raw onions; K.C., by contrast, favors tomato and cucumber on whole wheat. Joe moonlights as a real estate agent, hawking scuzzy properties that secretly belong to him; K.C., who dreams of becoming an actor, is getting set to play the lead role in ''A Streetcar Named Desire'' (yes, he rehearses by going out onto his apartment balcony to yell ''Stella!''). Joe, a late-night-whiskey loner, has three ex-wives; K.C., a tantric-sex devotee, teaches a yoga class attended by a bevy of young lovelies who would like to get to know their instructor better. Throw into the mix that Joe, who looks to be in his robust early 50s, acts as if he were K.C.'s disgruntled grandfather, and you've got the recipe for a buddy movie broad enough to make the ''Lethal Weapon'' series look like a paragon of subtlety.
At moments, it is indeed that broad, yet the director, Ron Shelton, working from a script that he wrote with Robert Souza, has a trick up his sleeve; it's his cheery skewed tone. ''Hollywood Homicide'' is a movie set in Los Angeles that is really, truly about Los Angeles -- a city of hustlers in which everyone, including the cops, is working some angle, some cracked scheme or dream, a barely private second identity that is hardwired to showbiz or fast money (or both). Joe and K.C. are assigned to a multiple murder case within the hip-hop demimonde. As they begin to investigate, they uncover a burbling underground of vanity and double-talk that they're implicitly in sync with, and the movie, like a light-comedy version of Dennis Hopper's 1988 ''Colors,'' finds a scruffy valor in their self-centered haplessness. Joe is pursued by an Internal Affairs investigator (Bruce Greenwood) who is out to nail him on infractions like ''the commingling of funds,'' and the joke is that the IA enforcer may be right, but he's also a prig. Crafty commingling, the film says, is what police work is all about.
A trio of rappers has been assassinated after a performance at a downtown club. The clues all point to the head of the group's record label, Antoine Sartaine (Isaiah Washington), a handsome smoothie in bespoke dark suits who has a way of making the music business sound far more benign than it is. How tough an investigator is Joe? He's so tough that Ford actually deigns to play him without his trademark midlife-crisis earring. Yet Joe, if anything, is even more possessed by his real estate deals. As the picture goes on, he tries, with a kind of slipshod fury, to broker a sale between an aging movie producer (Martin Landau) and the club owner who is part of the case (Master P), and the fast and loose atmosphere of casual profiteering does something for Ford; it tweaks his stony gravity.
Josh Hartnett seems to hail from a completely alternate emotional gene pool. Skinny and peachy-skinned, with hair swept sloppily to the side, the young actor is just this side of squishy -- too reticent, really, to be a cop. Yet that very incongruity works for the movie. Hartnett exemplifies a generation so pacified that it seems to have grown up without anger, whereas Ford has only gotten surlier with age; he's now the sort of star whose scowl is far more winning than his smile (perhaps because it looks more honest). Shelton, whose best movies are his grown-up sports comedies, ''Bull Durham'' and ''Tin Cup,'' knows how to get under the skin of stubborn, quirky machismo, though his cultural jokes are starting to date him. It's always a pleasure to see Lena Olin looking lithe and fabulous, but did Joe's talk-radio-host girlfriend really have to be a psychic astrology freak?
The rap world, with its hype and violence and clandestine scandals, is ripe for a thriller, but Shelton, whose ''Dark Blue'' earlier this year was a far more serious cop movie about race and murder in L.A., never begins to navigate its depths. The investigation in ''Hollywood Homicide'' draws broadly on elements from the murders of Tupac Shakur and Biggie Smalls, and the slick entrepreneur Sartaine is probably meant to evoke the hip capitalist élan of Sean Combs, but Shelton doesn't push beyond the allure of surface gossip. He uses it as a topical hook, building to a smash-and-grab chase through greater Beverly Hills that feels as if it goes on forever. Is it, you know, fun? At times. Yet there's a rote quality to the way this half-dumb, half-sly movie resolves itself into an intentional debauch, a pileup of villainy and heavy metal. The only California dream it leaves you with is one of wretched excess.