"Inherent Vice" might have been more fun if it had been played a little straighter. Thomas Pynchon's 2009 novel, set in the Los Angeles beach-town culture of 1970, is a stoned shaggy-dog story that's fat with pulp-fiction signifiers: snarling cops, neo-Nazi bikers, Indochinese drug smugglers and, best of all, the Golden Fang — which might be a mysterious red-sailed schooner, a shadowy international heroin cartel or a syndicate of coked-up dentists.

Pynchon didn't pretend that any of this added up to much, which was fine; we enjoyed his taffy-pull prose and his little hipster jokes. But writer-director Paul Thomas Anderson doesn't take Pynchon's story seriously, either — a considerable misjudgment, I'd say. Pause for a moment to recall "Raiders of the Lost Ark," a movie that parodied the conventions of pulp thrillers but also functioned as one; it didn't let its parody take the place of its story. Anderson simply lays out Pynchon's giddy plot elements and invites us to join him in admiring them. He's unflaggingly faithful to the novel, but the result — in terms of narrative involvement and simple entertainment — isn't much of a movie. (Although, at a runtime of 2 1/2 hours, it's also too much of one.)

Pynchon's protagonist, a pothead private detective named Doc Sportello, is a character that was once eyed by Robert Downey Jr., who surely would have brought some energetic invention to the role. But Anderson ultimately cast Joaquin Phoenix in the part, and Phoenix, in overgrown mutton chops and ratty fatigue jackets, takes a mumbly Method approach to the part, rolling joints and squinting in reefer-hazed incomprehension as the story sprawls out around him.

It begins with a late-night appearance in Doc's beachside pad by hippie-chick siren Shasta Fay Hepworth (Katherine Waterston), his ex-girlfriend. She has become entangled with a millionaire real estate greedhead, named Mickey Wolfmann (Eric Roberts), and is now on the run from Wolfmann's wife, Sloane (Serena Scott Thomas), and Sloane's boyfriend, Riggs Warbling (Andrew Simpson), who want Shasta to assist them in committing Wolfmann to a mental institution. Shasta wonders whether Doc's unlikely current squeeze, Deputy District Attorney Penny Kimball (Reese Witherspoon), might be of help. As with so much else, Doc's not sure about that. (His motto: "Thinking comes later.")

In his PI office, which he shares with a speed-dealing medico, named Buddy Tubeside (Martin Dew), Doc is visited by ex-con Tariq Khalil (Michael Kenneth Williams), who's fresh out of stir and wondering what happened to his old gang turf, which is now being gentrified into something called Channel View Estates — a Mickey Wolfmann project, it turns out. Doc's inquiries take him to a hilariously garish massage parlor, called Chick Planet, where he encounters a dead body and, soon after, his longtime nemesis, LAPD Detective "Bigfoot" Bjornsen (Josh Brolin), a hard-nosed blockhead dedicated to the violation of civil rights wherever he may find them. Doc shakes off Bjornsen with the help of attorney Sauncho Smilax (Benicio Del Toro) and then moves on to ponder the problems of Hope Harlingen (Jena Malone), whose husband, surf-rock saxophonist Coy Harlingen (Owen Wilson), has suddenly gone dead — or maybe just missing. Before he knows it, Doc is snorting blow with a mad dentist, named Rudy Blatnoyd (Martin Short), huffing nitrous with one Clancy Charlock (porn star Belladonna), taking in Golden Fang tips from a squeaky masseuse, named Jade (Hong Chau), and woozily contemplating a contract killer, named Adrian Prussia (Peter McRobbie).

This is a lot of stuff, but it never coheres into much of a story. There's nothing at stake in the plot, and the characters are self-contained oddballs who don't really interrelate. Anderson's longtime cinematographer, Robert Elswit, provides some gorgeous golden-hour lighting, and there's an amiable guitar-noodly score by Jonny Greenwood (bolstered with vintage tracks by Neil Young, Chuck Jackson and Supergrass). But as a riff on the film-noir detective genre, the movie seems wary of the pulp pleasures of the old crime flicks that Pynchon referenced, so it never delivers them. This is a mystery, of sorts, but possibly not one you'd want to pay to see — not in a theater, anyway.

Kurt Loder is the film critic for Reason Online. To find out more about Kurt Loder and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.